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AlphaBASIC PLUS User`s Manual

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1. COMPLP SWA SIZE SET SWA SIZE else COMPLP SWA SIZE COMPLP SWA SIZE margin end if if EXTRA SWA SIZE 0 COMPLP SWA SIZE COMPLP SWA SIZE EXTRA SWA SIZE end if COMPLP SWA SIZE COMPLP SWA SIZE rounded up to even number write COMPLP SWA SIZE to RP or SPG file margin is calculated in version 1 0 269 as if COMPLP SWA SIZE lt 256 COMPLP SWA SIZE COMPLP SWA SIZE 50 else COMPLP SWA SIZE COMPLP SWA SIZE 1 1 end if You can have multiple PRAGMAs altering the SWA size in a source file The PRAGMAs will interact as defined above In conjunction with the conditional compilation PRAGMA directives such as IF you can tune the RP files SWA requirement AlphaBASIC PLUS User s Manual Rev 02 The String Work Area Page I 3 If you CHAIN from one RP file to another with CHAIN MYFILE RUNP will not delete its existing SWA and reallocate the SWA with the size specified in the incoming RP file The second RP file will use the freshly initialized SWA of the first RP file Therefore the first RP file must specify the maximum size of the SWA for its own requirements and for all RP files that it CHAINs to If you need to CHAIN to another RP file and use its SWA setting you must cause R
2. Note any statement following a REM keyword on a line is NOT executed by AlphaBASIC PLUS When the program is compiled everything following the REM statement on the line is ignored The comment symbol is an abbreviation of the REM statement and is used the same way For instance PRINT TRY ANOTHER TIME IF THEY MISS BETWEEN GOTO AGAIN ONE AND THREE TIMES Like the REM statement anything following the symbol on the line is ignored You may comment out a section of a program containing comments For example REM PRINT TRY ANOTHER TIME IF THEY MISS BETWEEN REM GOTO AGAIN ONE AND THREE TIMES 2 4MULTIPLE STATEMENT LINES AlphaBASIC PLUS supports multiple statement lines Multiple statement lines can be formed by using colons to separate the statements For example these lines FOR I 1 TO 10 PRINT This is a loop NEXT 1 could be written as FOR I 1 TO 10 PRINT This is a loop NEXT I The exception is a DATA statement cannot contain other statements on the same line and no other statements may follow a comment designated by REM or Direct statements in interactive mode may also be multiple statement lines 2 5CONTINUATION LINES COMPLP allows the use of continuation lines within the source program That is
3. Here are the results of using the command in interactive mode to determine the locations of several of the variables above READY AlphaBASIC PLUS User s Manual Rev 02 Mapping Variables Page 14 15 CUSTOMER ID EUN MAP1 Unformatted size 279 located at 0 278 TRANSACTIONS MAP2 Unformatted Array 12 size 18 base located at 63 QCITY RETURN MAP3 String size 10 located at 45 54 HOME RETURN MAP3 Binary size 3 located at 57 59 We can also use the command to locate unmapped variables For example READY DIM A 2 3 QA RETURN Dynamic AMOS Floating point Array 2 3 size 6 A 15 ETUAN 2 A RETURN Fixed AMOS Floating point size 6 located at 72 77 Dynamic AMOS Floating point Array 2 3 size 6 Note we allocated two different variables a fixed floating point variable A and a dynamic floating point Array variable A 2 3 AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 15 THE FILE INPUT OUTPUT SYSTEM This chapter contains information on creating and using disk files from within your AlphaBASIC PLUS program The following subjects are discussed eHow to identify files einput output statements eSequential files eRandom files eHow to lock files erile statements 15 1 WHAT IS A DISK FILE A disk file is a group of data items stored on a hard disk device AlphaBASIC PLUS programs are usually stored on the disk as a disk file But AlphaBASIC PLUS can use
4. Notice from the examples above you may sometimes omit the GOTO keyword when transferring control to another program location You may NOT omit the GOTO keyword when you are referring to a label or when you are in an ELSE clause and referring to a line number The above formats may be nested to a depth that depends on the amount of memory you have available in your memory partition You may often omit THEN also You can t omit THEN if you are transferring control to another area a line number or label and you don t have a GOTO A transfer of control must have either a THEN or a GOTO Some examples A 5 THEN GOTO PROGRAM EXIT A gt 14 THEN 110 ELSE GOTO 220 BS END PRINT END OF TEST TOTAL 14 5 GOTO START P 5 AND Q 6 IF R 7 PRINT 567 ELSE PRINT 56 ELSE PRINT NONE A 1 PRINT 1 ELSE IF B 2 amp THEN 335 ELSE GOTO 345 IF A AND B THEN PRINT A and B are nonzero Hj no hl Aj V E AlphaBASIC PLUS User s Manual Rev 02 Page 9 14 Chapter Nine IF Revenue gt Expenses THEN PRINT We have made a profit GOSUB Print Stockholders List GOSUB Print Caterers Phone Numbers ELSE PRINT We hav xperienced a loss GOSUB Print Company Budget B B GOSUB Print Employee List GOSUB Print Problem
5. or PRINT The answer is SOR 16 Functions either return a numeric or string value the descriptions below describes the arguments each accepts and what type of value is returned m You can also define your own functions see Chapter 20 Note the mode independence feature of the expression processor performs automatic conversions if a numeric argument is used where a string argument is expected and vice versa AlphaBASIC PLUS User s Manual Rev 03 Page 10 2 Chapter Ten 10 1NUMERIC FUNCTIONS Numeric functions accept a string or numeric argument and return a numeric value The following numeric functions are supported 10 1 1 ABS X Returns the absolute value a positive number of the argument X For example READY PRINT ABS 32 4 3254 PRINT ABS 17 2 REUN Lee 10 1 2ASC X Returns the ASCII decimal value of the first character of argument X The argument may be any string expression For example READY First Name Amy PRINT ASC First Name 65 You may also use string literals PRINT ASC Z 90 10 1 3EXP X Returns the constant e 2 7182818285 raised to the power X e is the base of the system of natural logarithms 10 1 4FACT X Returns the factorial of X A factorial is the result of multiplying the number X by all integers less than X i e if X 7 the factorial equals 7 6 5 4 3 2 1 For example READY PRINT FACT 4 24 This function actually is t
6. Another section of the program might want to read in a record of data By using a simple statement READ 1 CHECK INFO AlphaBASIC PLUS User s Manual Rev 02 Page 14 12 Chapter Fourteen we can bring in all the information related to that check This is much easier than using 11 statements to read in the 11 variables contained in CHECK INFO We can also use the individual items in AlphaBASIC PLUS program statements For example IF AMOUNT gt 100 GOTO VERIFY TRANSACTION 14 5HOW VARIABLES ARE ALLOCATED IN MEMORY E This section goes into the details of how memory is mapped If you are not interested in this you may want to skip to the next chapter During compilation AlphaBASIC PLUS allocates memory storage for all defined variables in a contiguous and predictable area The compiled program refers to all variables by an indexing scheme Each variable in the working storage area has a representative item in the index area which contains all the information needed to define and locate that variable The working storage area therefore contains only the pure variables themselves without any associated or intervening descriptive information The index area is a separate entity physically located before the working storage area in memory AlphaBASIC PLUS normally allocates variable storage as it encounters each variable during compilation A different method must be derived which can over
7. statement s LOOP WHILE and or UNTIL condition The DO reserved word marks the beginning of the loop If WHILE is used with a condition the statement s that make up the loop are executed if the condition is TRUE If UNTIL is used the statement s are executed if the condition is FALSE If condition is not met control passes to the first statement after LOOP If condition is met the statement s are executed Then LOOP is executed and its WHILE UNTIL condition is evaluated if it contains one If that condition is met control passes back to DO The DO LOOP cycle continues until a WHILE or UNTIL passes control out of the DO LOOP or until an EXIT occurs For example DO WHILE Control Number gt Count RINT Item Number Count ount Count 1 EAD 1 Next Inventory Item RINT Next Inventory Item Uu O U LOOP In the above program section the DO LOOP is executed as long as Control Number is greater than Count The advantage of the DO LOOP structure is its flexibility the test can be at either end or both of the loop or in the middle of the statements You may use an EXIT statement to make tests in the middle of the loop see below You can also easily have multiple tests Another example AlphaBASIC PLUS User s Manual Rev 02 Page 9 6 Chapter Nine NUM TEST 0 DO WHILE NUM TEST lt MAX TEST NUM TEST NUM TEST
8. 22 5 16Change a Variable Value LET sets a variable to the specified value The format is LET variable value For example gt LET Credit Balance 1034 92 Do not put quotes around string values AlphaBASIC PLUS User s Manual Rev 02 Page 22 8 Chapter Twenty Two 22 5 17Re Start Debugging NEW re initializes the debugger the program is ready to begin again at the beginning All of the variables are cleared etc 22 5 18Run Program From Program Pointer PROCEED or RUN runs the program starting at the current program pointer the next step to be executed This is useful is you have been single stepping through the program and wish to begin conventional execution 22 5 19Exit Debugger QUIT exits you out of the debugger to AMOS command level 22 5 20Clear Error REMOVE clears an error condition Execution of the program does not resume 22 5 21Clear Error and Resume Execution RESUME clears an error condition and starts the execution again You may specify a label to start the execution again For example gt RESUME FED TAX RETN 22 5 22Set Scale Factor SCALE sets the scale factor to the specified value or prints the current value if no value is entered For example gt SCALE 7 22 5 23Set Significance Value SIGNIFICANCE sets the significance to the value specified or prints the current significance if no value is entered For example gt SIGNIFICANCE 10 AlphaBASIC PLUS User s Manual Rev 02
9. The maximum size of any AlphaBASIC PLUS statement including blanks tabs ampersands and carriage return line feeds is just under 1000 characters 2 6MEMORY ALLOCATION In interactive mode memory is allocated dynamically as you edit your program and also during its compilation and execution Checks are made to tell you if you have run out of memory If you do you get an error message If you run out of memory while COMPLP is compiling a disk program you see an error message and the compilation stops See Appendix for more information on AlphaBASIC PLUS memory allocation 2 7SEARCHING FOR A LIBRARY Whenever a program or subprogram called with a RUNP command a CHAIN statement or a SUBCALL statement or a subroutine called with an XCALL statement is requested AlphaBASIC PLUS tries to execute the requested program subroutine If the program subroutine you request is not specified with a complete file specification AlphaBASIC PLUS looks for it assuming a number of default specifications AlphaBASIC PLUS follows a specific pattern in looking for the requested run or subroutine module If you specify an account then AlphaBASIC PLUS uses the current default device and the specified account If you don t specify an account the search sequence is AlphaBASIC PLUS User s Manual Rev 02 General Information Page 2 5 1 Your memory partition 2System memory 3Your disk Your account 4 Your disk Your Library account P 0
10. seen 19 6 19 3 1400 RELEASE ALL 0 0000 00 Rh 19 7 T9 3 Ib POSEE aerem EU hn eui ait 19 7 19 942 GLOSEK o ere tette e sto tinte fes a 19 7 19 313 UNEONKR coso nu ERI ERR sere Paha ets 19 7 19 4 CREATING AN ISAM PLUS FILE een 19 8 19 4 1 ALLOCATE INDEXED esn RR RR RI 19 8 19 5 RETRIEVING STATISTICAL INFORMATION 000 19 8 19 5 1 INDEXED STATS sseee RR eh 19 8 19 6 ERROR PROCESSING ssee eee 19 9 CHAPTER 20 USER DEFINABLE FUNCTIONS 20 1 WHY USE DEFINED FUNCTIONS sen nnn 20 1 20 2 SINGLE LINE FUNCTIONS een RR IR 20 1 20 3 MULTIPLE LINE FUNCTIONS 0 0 00 0 RR RR 20 2 20 4 LOCAL VARIABLE AND PARAMETER TYPES 20 3 20 5 USING DEFINED FUNCTIONS lsne RR RR 20 4 20 6 EXAMPLES util te Rees e eco haces D ne dia 20 5 CHAPTER 21 THE UNIFY RDBMS INTERFACE 21 1 WHAT IS UNIEYA2 e abemus 21 1 21 2 UNIFY XCALL FORMAT see RR RR RR RR rns 21 1 CHAPTER 22 THE ALPHABASIC PLUS DEBUGGER 22 1 SETTING UP YOUR PROGRAM FOR DEBUGGING 22 1 22 2 CALLING THE DEBUGGER esses 22 1 22 9 WHAT YOU SEE frora REED ay fee a 22 1 22 4 CONTROLLING PROGRAM EXECUTION 000 22 2 22 5 COMMAND MODE 0 000000 RR RR rss 22 3 22 5 1 Print Variable Value lee BR 22 4 AlphaBASIC PLUS User s Manual Rev 04 Table of Contents Page ix 22 5 2 See Variable Informa
11. Here is a program example using READ RESTORE and DATA START INPUT LINE How much did you pay for your car WORTH Based on national averages your car amp will depreciate PRINT FOR I 1 TO 5 After the READ YEARS YEARS year your car will be worth about READ PERCENT AlphaBASIC PLUS User s Manual Rev 02 Page 9 26 WORTH WORTH PERCENT WORTH USING SS HEM NEXT DATA firs R ESTORE IF INI EN PUT DIF 9 37RENAME Renames a disk file The format is R ENAME Chapter Nine t 77 second 78 third 79 fourth 81 fifth 84 LINE Would you like to see another schedule LS UCS LS 1 1 Y THEN GOTO START ELSE PRINT Goodbye old filename new filenamef status or R ENAME old filename TO new filename status The filenames can be any string expression The stat tus is a variable containing a value returned by RENAME based on the results of the renaming operation If status 0 the rename worked fine If status 1 an error occurred at AMOS level and the file wasn t renamed If you don t specify a status variable a run time error is generated if an error occurs at AMOS level For example if you try to rename a file that doesn t exist stat
12. 20 3MULTIPLE LINE FUNCTIONS The format is O EF FN name parameter list local variable list line s of definition ENDEN The value of the function is determined by setting the function name in an assignment statement in the body of the function for example FN Total 2 The type of value returned by the function depends on the naming convention of the variable used FNname A floating point variable returning a floating point number FNname An integer variable returning an integer FNname A string variable returning a string A function can have only one return type modifier DO NOT use and in combination The function value defaults to zero or null if it is a string if no value is specified If more than one value is specified the last one encountered is returned You may use EXIT statements within the function body to transfer control to the ENDFN statement Local variables defined within the function initially have a value of zero if numeric or are null if string As with standard variables you may append a sign to make the function value an integer or a to make it a string Variables defined in a function in the local variable list are local to the function only All variables defined in the main program can be accessed by the function There are a few things you cannot have inside a function definition eGOSUB statements into or out of the function AlphaBASIC PLUS Us
13. AlphaBASIC PLUS User s Manual Rev 02 Mapping Variables Page 14 13 14 6LOCATING VARIABLES DURING DEBUGGING A command has been implemented which can assist you in locating the mapped variables and in understanding the allocation techniques used by the AlphaBASIC PLUS variable mapping system The command has the general format of a commercial atsign O followed by a variable name The system searches for the requested variable and prints out all parameters about the variable for you on the terminal This may actually be two definitions since the variable A may actually be two different variables one could be a single floating point number and the other could be a subscripted array The information returned about the variable is eThe type of variable string binary etc eThe dimensions of the array if the variable is an array eThe size of the variable in bytes eThe offset to the variable from the base of the memory area which is used to allocate all variables If you enter a reserved word such as PRINT the system tells you the name is a reserved word If you enter an undefined variable AlphaBASIC PLUS informs you The general format of the definition line returned by the system is memory type var type dimensions size n located at x For actual examples of the definition line see the Examples section below memory type is the method of memory allocation used when defining the variable memory type may be MAPn wher
14. CALL label or line number RETURN These commands call a subroutine which starts at the line number or label specified in the GOSUB or CALL statement When RETURN is encountered the subroutine returns to the statement immediately after the GOSUB or CALL Executing RETURN without first executing GOSUB results in an error message Both GOSUB and RETURN are illegal as direct statements in Interactive Mode Note the CALL statement is merely another way of specifying GOSUB for those programmers used to this syntax from other versions of BASIC or other programming languages It is often the case you want to perform the same operation or series of operations at various points within your program A subroutine is a set of program statements you may execute more than once simply by including a call for that subroutine within your program at the point where you want to execute the routine For example AlphaBASIC PLUS User s Manual Rev 02 Page 9 10 Chapter Nine This program has a subroutine that validates numeric entries to make sure they are gt 0 and lt 100 PRINT We re going to do some mathematical operations R RE START R R gt T Your entries must be gt 0 and lt 100 T INPUT Enter two numbers to be added A B UB VALIDATE Check if numbers are valid FLAG 1 THEN GOTO RE START Check error flag INT A B A B NT INPUT Enter two numbers to be subtracted A B UB VALIDA
15. More Interactive Commands Page 4 3 4 3STOPPING A PROGRAM RUN Pressing c amp Cc stops a running program Depending on the operation being done c may display on your terminal The line number of the source program at which the program was interrupted is displayed in the message For example cm C or nothing Operator interrupt in line 70 READY You cannot continue a program after you have entered a muog 4 4LOADING A PROGRAM INTO MEMORY LOAD If you have a program saved as a disk file you can load it into temporary memory so you can edit or run it To do this enter LOAD and the name of the file For example READY LOAD NEWPRG BP 100 1 READY This program file could have been created using AlphaVUE or might have been saved from a previous interactive mode session If you do not supply a file extension AlphaBASIC PLUS uses the default extension of BP AlphaBASIC PLUS assumes the account and device you are logged into If AlphaBASIC PLUS can t find the file you want to load it displays Cannot open lt filespec gt file not found The LOAD command does not clear the text buffer before it loads the requested file and therefore may be used to concatenate or merge several programs or subroutines together to be saved as a single program The separate routines must not duplicate line numbers in the other routines they are to be merged with or else the new line numbers overlay the old ones j
16. The File Input Output System Page 15 3 15 4SEQUENTIAL FILES Sequential disk files are the easiest to understand and to implement in AlphaBASIC PLUS AlphaBASIC PLUS writes data to a sequential file in ASCII format and stores numeric data as ASCII string values if possible A sequential data file usually has the extension DAT and AlphaBASIC PLUS uses DAT as the default extension Typical sequential data files are normal ASCII files in all respects and you may edit them by using AlphaVUE or any of the system utilities To open a sequential file use the OPEN statement see below specifying INPUT OUTPUT or APPEND mode Use the PRINT statement followed by a non zero file channel number to write data to sequential files The PRINT statement automatically appends a carriage return linefeed to your data in the same manner it does when sending data to a terminal display unless a semi colon follows the data PRINT also converts floating point and binary data to printable ASCII form Use INPUT INPUT LINE or INPUT RAW followed by a non zero file channel number to read data from a sequential file See the examples below The following sections contain step by step instructions for using sequential files in the various modes the commands used are discussed in detail later in this chapter USING SEQUENTIAL FILES FOR OUTPUT 1Use the LOOKUP command to see if the file already exists When you output to a sequential file you are creat
17. User definable functions are illegal as interactive mode direct statements AlphaBASIC PLUS User s Manual Rev 02 User Definable Functions Page 20 5 Appendix for details m You may need to adjust the size of the String Work Area in certain cases See 20 6EXAMPLES Here are some examples of defined functions DEF FN Dice Roll INT 7 1 RND 0 1 DO Loop counter Loop counter 1 RANDOMIZE First die FN Dice Roll Second die FN Dice Roll Roll First die Second die PRINT The dice roll was Roll LOOP UNTIL Roll 12 PRINT It took Loop counter rolls to roll a 12 Here s a more complex multi line function MAP1 Employee Name S 25 Employee Number 4 DEF FN Wages Hours Salary Over hours Hold Variable IF Hours gt 40 THEN Over hours Hours 40 Hours 40 Hold Variable Hours Salary FN Wages Hold Variable Over hours Salary 1 5 ENDE N FOR I 1 TO Employee Number READ Employee Name Salary PRINT Hours for employee Employee Name INPUT Hours Wages FN Wages Hours Salary PRINT Employee Employee Name to be payed Wages DATA Ralph Habshatz 5 10 DATA George Carver 4 65 DATA Susan Winters 6 35 DATA Winston T Murgrove 13 76 AlphaBASIC PLUS
18. 16 2 1Subroutines User Defined Functions and Subprograms When you call a subroutine by using a GOSUB CALL statement the subroutine has access to all the variables and environment settings of the calling program If the subroutine alters the value of a variable the calling program sees that change after RETURNing from the subroutine Any changes in the environment such as changing the ON ERROR destination or READing from the DATA pool are also effective in the calling program The statements making up the subroutine are placed in the same file as the statements for the calling program and are compiled together into a single RP file Therefore the subroutine cannot be accessed from another RP file instead you have to copy the subroutine s statements into the second file or use a INCLUDE statement duplicating code and making the space taken up by the RP files larger User defined functions put a thin wall up between the calling program and the statements inside the user defined function User defined functions support the passing of parameters as well as the use of local variables Local variables are not visible from the calling program and so give you a safety net you can use them without affecting any variable of the same name in the calling program The parameters allow you to pass variables to and from the function if you alter the value of a parameter in the user defined function the corresponding variable in the calling program
19. AS ABCDEF UN A 2 4 Ge PRINT AS RETURN A t EF This procedure may not be applied to numeric variables for example A 3 2 23 is not valid when A is a numeric variable When substring modifiers are used on the left side of an assignment the values represent the character position within the variable For all other uses the values represent the character position within the string which is contained within the variable 8 3SETTING THE SIZE OF THE STRING WORK AREA When RUNP executes a compiled program it may have to manipulate string expressions which the programmer coded RUNP allocates an area of memory the string work area SWA for this manipulation The size of this area is decided by COMPLP the compiler In most cases the compiler can accurately estimate the required size of the SWA but in some cases the programmer may need to increase the size lt is also possible to decrease the size of the SWA A manual intervention can be required if the SPACE or FILL functions are used where the size of the resultant string is specified as a run time expression e g SPACE len A 2 when certain subprograms are SUBCALLed or certain user defined functions are executed The size of the SWA can be altered from the compiler set value by using PRAGMA compilation statements See the section of PRAGMA in Chapter 5 for details The size of the SWA in a RP file can be determined by using the R option of RUNP S
20. Here are some tips things the second program used the first did not elf possible do not use line numbers They make your program harder to read and update lf you want to insert lines you may have to renumber the rest of the program Without line numbers you can also more clearly indent the program lines to show levels and structures eUse descriptive variable names ANSWER instead of D for example and labels This makes the program easier to understand eDo what you can to make the program easy for the user The second program used UCS on QUERY before comparing it to Y In the first program if the user answers the question with a lower case y the program ends Good programs don t allow a user to enter incorrect responses eUse spaces to make lines easier to read In most cases AlphaBASIC PLUS ignores blank spaces so you can use them to make text more readable For example AlphaBASIC PLUS User s Manual Rev 02 Page C 4 Appendix C ANSWER FIRST SECOND THIRD 3 instead of 13 D A B C 3 eUse MAP statements so all variables are defined at the front of the program This is especially useful in large programs The programs above were too simple to show the use of some ideas We have tried to use examples throughout this book written in structured clear code both to make our examples easier to read and to encourage good program style Here are a few more things you may want to keep in mind
21. INPUT LINE file channel variable The INPUT LINE statement operation is identical to that of the INPUT statement with the exception that input into a string variable accepts the entire line up to but not including the carriage return and linefeed that ends the line This allows commas quotes blanks and other special characters except NULLs to be input Also INPUT LINE accepts blank lines as input INPUT LINE is usually used for string input rather than numeric AlphaBASIC PLUS User s Manual Rev 02 Page 15 14 Chapter Fifteen 15 9 8INPUT RAW Used to input raw data from a file INPUT RAW does no processing of the data The format is INPUT RAW file channel variable variable s where variables are unformatted variables of whatever length you specify when you define them Each variable is filled to its length with characters from the file including carriage returns non printable characters etc 15 9 9KILL The KILL statement erases a file from the disk It does not need a file channel number to KILL a file The format is KILL filespec result variable For example KILL NEWDAT DAT As in the OPEN statement filespec is any string expression which evaluates to a legal file description The default extension is DAT If you try to erase a non existent file you see a File not found error message To avoid this error use the LOOKUP statement discussed below Do not try to KILL a file you
22. 1 23 24 25 Output the day of the week Do not output the day Overrides Options 6 and 19 Do not output the month Overrides Options 3 and 4 Do not output the year Overrides Options 5 and 16 AlphaBASIC PLUS User s Manual Rev 04 Functions Page 10 15 Weekday Options 2 Use the full text for the weekday otherwise use a three letter abbreviation A comma will be added if alphabetic output is generated and the date follows the weekday Requires Option 1 Option 22 if set overrides this option 22 Output the weekday as a number 0 6 as the first element of date output Overrides Option 2 requires Option 1 to be set Day Options 19 Add English day suffix st nd rd th to the numerical day output Forces Option 14 on for day output Month Options 3 Output the month as a number 1 12 ignore Option 4 4 Use the full text for the month otherwise use a three letter abbreviation Year Options 5 Output a four digit year otherwise use a two digit year Option 14 may disable leading zeros for two digit years Option 18 may force them on 18 Force leading zeros in two digit years for years in the range xx00 xx09 Overrides Option 14 TIME FORMATTING 11 Use 12 hour and AM PM otherwise use 24 hour time 15 The time value is supplied in separated format Otherwise the time value is in internal format 28 If 24 hour clock output hrs after the time string Otherwise ignored Hours Options 12 Do not output a
23. 1 through 32 inclusive and 33 through 64 inclusive For each group 1 Start with a 32 bit number 00000000000000000000000000000000 2Number the bits from right to left starting with the low order bit starting with 1 for the 1 32 group or 33 for the 33 64 group 3For each option set the option number s bit to a 1 Thus for options 1 3 and 6 set 00000000000000000000000000100101 4Read that back as a decimal value 144432237 5Use that value in the PX command For the first group use PX1 For the second use PX2 For options 1 3 6 COMPLP MYFILE PX1 37 EUR There is no corresponding shorthand for PRAGMA FEATURE as there can be multiple PRAGMA lines in the file However all the PRAGMA FEATURE lines must be at the top of the source file before COMPLP generates any object code i e prior to any VERSION statements INCLUDE statements or MAP statements Note that versions of RUNP earlier than 1 0 267 do not have any option facilities and they are effectively blind to such requests Files compiled under COMPLP 1 0 267 and later with option settings will be erroneously executed under RUNP version 1 0 266 and earlier without any indication of an error AlphaBASIC PLUS User s Manual Rev 03 Page J 4 Appendix J J 5EFFECTS OF USING OPTIONS The use of compatibility options requires the correct versions of COMPLP and RUNP to fit the situation This section explains the implications of mixing COMPLP and RUNP
24. 30 PRINT INPUT Enter a number NUM Enter a number 154 5 ETA D 40 VALUE VALUE CONSTANT NUM I PRINT VALUE REUN 169 5 ee 160 EN 50 NEXT I y 60 PRINT VALUE 160 End of Program Note line 30 is a multi statement line When single stepping all statements on a line are executed at the same time AlphaBASIC PLUS User s Manual Rev 02 More Interactive Commands Page 4 5 At each point after a line has been executed you can use direct statements to look at or change variable values as we did with the PRINT VALUE and VALUE 160 direct statements in the example before you continue the run of the program by using CONT or by pressing J Note any change in the source program causes AlphaBASIC PLUS to recompile the program The next single step command then executes the first line of the program When we changed the variable VALUE to 160 we didn t change any of the program lines therefore AlphaBASIC PLUS didn t recompile the program Only a variable was changed The single step feature can be used at the beginning of the program after program STOP statements and breakpoint interrupts After partially single stepping through a program you may execute the remainder of it normally by using CONT Also you may start over at the beginning and execute it normally by using RUN If you try to single step past the End of Program message the first program statement e
25. AlphaBASIC PLUS uses the name of the terminal driver for the terminal being used as the translation table name This allows you to make your translation tables terminal specific The FIXTRN program creates these translation tables Only modules created by FIXTRN are valid for use with GETKEY f you use an invalid translation table you may get erroneous results See your System Commands Reference Manual for information on FIXTRN Let s look at an example of how a translation table works After defining a translation table so the HELP key translates to H and the MENU key translates to M and placing this XT XLT file in user memory this program shows how to make use of them START a getkey 1 xt xlt print a chr a if chr a H then goto HELP if chr a M then goto MENU if chr a lt gt E then goto START HELP print This is the HELP screen goto START MENU print This is the MENU screen goto START 10 4 80DTIM Returns a formatted string of the specified time and date The format is ODTIM date time flag value The flag value determines the format of the time and date You determine the flag value by first deciding which options you want from these lists AlphaBASIC PLUS User s Manual Rev 04 Page 10 14 Chapter Ten ORDERING AND FORMATTING OPTIONS 0 9 14 26 Omit date from the output and ignore all other date formatting flags Omit time from t
26. Code ONGO 11 15 17 19 21 Meaning Operator interrupt Out of memory NEXT without FOR RESUME without ERROR Numeric point overflow Illegal function value File already open Record size overflow File not found Device full Device in use Code Meaning System error Out of data RETURN without GOSUB Subscript out of range Divide by zero Subroutine not found IO to unopened file channel File spec error Device not ready Device error PPN not found AlphaBASIC PLUS User s Manual Rev 02 Error Trapping Code Meaning 23 Protection violation 25 File type mismatch 27 Bitmap kaput 29 File already exists 31 Illegal record number 33 Stack overflow 35 Unsupported function 37 Filein use 39 Deadly embrace possible 41 File cannot be RENAMEd 43 System error 45 Device not file structured 47 0 illegal for random files 49 Channel inappropriate file I O 51 Firstlogical unit not mounted 53 Illegal key number 55 Undefined array in XCALL 57 Reserved for expansion 59 Reserved for expansion 61 Translation table not found in memory 63 Too many parameters 65 Channel number in use 67 String Work Area Exceeded 69 Cannot find subprogram array 71 Not enough memory to load XCALL routine 73 Cannotrun RP with DIM statements from RES or MEM 17 4THE RESUME STATEMENT Code 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 Page 17 3 Meaning Write pro
27. IF clause for instance to signal a section of code as yet uncompleted string is the error message to display Note that string is printed out without being processed or interpreted in any way Used like an IF THEN statement this lets you set a condition to be met before a section of the program is compiled The constant expression must use a defined value not a variable Used with IF to compile an alternate section of code if the constant expression is false Short for ELSE IF lets you nest IF clauses Signals the end of the condition compile section of code Used like IF compiles the designation code if the variable is defined in the program Used like IF compiles the designation code if the symbol is not defined in the program Similar to ERROR but does not cause a compilation error to print or the compilation to stop Affects the compilation process allowing the setting of various options from within a source code file Most PRAGMA lines have the form PRAGMA setting value which will cause the variable specified by setting to take on the value specified by value See the section PRAGMA Setting Compiler Options below AlphaBASIC PLUS User s Manual Rev 03 Writing Program Files Page 5 7 5 4 1Including Other Files in Your Program The INCLUDE statement lets you bring other files into your program at the point of the INCLUDE All the statements in the included file are compiled as
28. ON ERROR GOTO oi odscus rare e 9 20 17 1 ON GOSUB iure ser para ee ee 9 20 OPEN ora eee Sade 15 6 15 16 15 19 15 21 Modes 0000 eee cease 15 18 OPEN statement 2 19 3 Opening an ISAM PLUS file 19 3 A eed geret Pet ee 7 6 Operator precedence 7 3 A eG eh ore bA 7 2 OUTPUT mode niv ret ee an e 15 16 Overlaying variables in memory 14 7 PARAMETER br REeEREE RES 16 8 Pass by reference 16 8 Pass by value oooooooooo 16 8 Parentheses scires Ree BES 7 1 Pause inaprogram 9 28 to 9 29 PEEK Lice d eg weg PI Oed 11 1 PHDR macro 000e essen E 4 Physical blocks ose nw ors 15 5 Physical memory lllssss 11 1 POKE tia sh ed ob ed ened e A 11 1 EDI ine ciate ost eae ey alee hoes oa rears 1 6 PRINT 35e Egoh ti EP Me URS mete 2 7 6 9 21 12 1 12 9 15 2 15 12 15 19 PRINT USING sutte coh ee es 9 23 9 28 12 1 15 19 Printzones co 9 22 PROCEED 342 ash sue ve ERE ba 22 8 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index Program cocidos Compilation Debugging Edit number Execution FON zn dada birra 4 Indentation Major revision number Minor revision number Pausifig i unes e mes Revision subscript RUN zero ERES Statements Version num
29. Output British pound character Output Pi character Enter bidirectional print mode Exit bidirectional print mode Set terminal time Set terminal date Select color palette by HLS value Select PC character set Select default character set Select PC terminal emulation Select ASCII terminal operation Select AUX port host Select main port host Select toggle host ports Select 8 bit character display Select 7 bit character display Select 8 bit keyboard mode Select 7 bit keyboard mode Select primary printer port Select secondary printer port Select 161 column display mode The actual routines that perform the screen controls are in the specific terminal drivers and not in AlphaBASIC PLUS itself Not all terminal drivers have all of the functions above simply because not all terminals are able to perform all of these functions The TRMCHR XCALL can be used to check if your terminal implements some of these features See Chapter 9 of the AMOS AlphaBASIC XCALL Subroutine User s Manual for further details AlphaBASIC PLUS User s Manual Rev 02 APPENDIX E WRITING ASSEMBLY LANGUAGE SUBROUTINES This appendix provides details on assembly language programming for those who want to write assembly language subroutines for AlphaBASIC PLUS programs For further information about assembly language see your Assembly Language Programmer s manual and your AMOS Monitor Calls Manual AlphaBASIC PLUS programs are different from AlphaBASIC p
30. Process aborted by operator C Command line format error Command line switch error Bad SSD Overlay not found AlphaBASIC PLUS User s Manual Rev 02 APPENDIX H MEMORY This appendix discusses AlphaBASIC PLUS memory requirements and how you can control how memory is used in your user partition H 1MEMORY REQUIREMENTS Several factors determine the amount of memory you need to run any AlphaBASIC PLUS component eThe size of the program itself However if the program is loaded into system memory you don t need to load it into your partition and you can ignore this size eEach program needs a certain amount of additional memory to operate this is called the DSECT size Finally AlphaBASIC PLUS needs to create a stack an area of memory in which to store variables and do computations You can control the size of this stack area with the MINS and MINF definitions in a BPR file BPR files are explained later in this appendix The table below shows the sizes of these factors for each AlphaBASIC PLUS component By adding the appropriate numbers together you can see how large a partition you need PROGRAM SIZE DSECT MINF MINS TOTAL SIZE default default default BASICP LIT COMPLP LIT RUNP LIT Remember the size of the program doesn t need to be considered if it is loaded into system memory in the system initialization command file AlphaBASIC PLUS User s Manual Rev 02 Page H 2 Appendix H Note that t
31. Rev 02 Page A 10 Appendix A lllegal or undefined variable in overlay The variable specified in a MAP statement overlay preceeded by has not been previously defined or is not a mapped variable Check your spelling You may want to define a MAP statement for the variable or remove the lllegal PRINT USING format The edit format used in a PRINT USING statement is invalid lllegal PROGRAM argument Make sure you entered the argument correctly and the numbers are within the parameters allowed by the PROGRAM statement lllegal record number The relative record number specified in a random file processing statement READ or WRITE is either less than the current FILEBASE or outside of the file Or the record size of a contiguous file and the relative record number do not match the physical size of the file on disk lllegal record size The record size specified in a random file processing statement READ or WRITE is outside the range the file was OPENed for Check your OPEN statement lllegal REPEAT or EXIT usage Check your syntax and take out or re locate the statement lllegal SCALE argument The argument given in a SCALE statement is invalid The argument must range between 35 and 35 Check your argument lllegal size for variable type The specified variable size is not valid for the particular variable type AMOS floating point variables must be size 6 binary variables must have sizes 1 through 5 integers must
32. Status Report Monday If you separate the expressions by commas AlphaBASIC PLUS prints the data in print zones AlphaBASIC PLUS divides the area in which data is to be displayed into five zones of 14 spaces each If an expression in a PRINT statement is followed by a comma AlphaBASIC PLUS prints that expression in the next available print zone For example the AlphaBASIC PLUS statements PRINT 34 1024 32 20 72 PRINT AA BR cn DDD e EE FFFEF display 34 1024 32 20 72 AA BB C DDD EE FFFF When you look at the display above remember AlphaBASIC PLUS prints numeric data with a leading and trailing blank if the number is positive but just a trailing blank if the number is negative AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 23 Note the strings in the second line were displayed on two different lines when AlphaBASIC PLUS still has an expression to print after it has printed something in the fifth zone it starts over again with the first zone on the next line If you end the PRINT statement expression list with a semicolon or comma AlphaBASIC PLUS does not output a carriage return linefeed when it finishes displaying that expression list This makes the output resulting from the next PRINT or INPUT statement appear on the current display line The next output appears in the next print zone if the current PRINT statement ends with a comma
33. The AlphaBASIC PLUS Debugger Page 22 9 22 5 24Break on Value Change TRACE breaks execution whenever the variable specified is about to be written to This lets you follow a variable through its changes For example gt TRACE Credit Limit TRACE may be made conditional also That is you can TRACE when the variable changes in a certain way For example gt TRACE Credit Limit gt 1000 FEA In this case DB breaks the execution only if the variable Credit Limit exceeds 1000 You can use all of the conditional expressions listed in Chapter 7 22 5 25Remove Tracepoint UNTRACE turns off the TRACE on the specified AlphaBASIC PLUS variable or turns off all TRACEs if no variable is entered For example gt UNTRACE Credit Limit 22 5 26Display List of Variables VARIABLE displays a list of variables in your program in definition order from the specified variable If no variable is entered it lists all variables TRACEd variables are displayed in reduced intensity if your terminal supports this feature MAPped variables are indicated and their type size and current value if not an array are displayed 22 5 27Break at External Program CHAIN causes the program to execute until the CHAIN call to the specified filename is encountered This lets you debug the subprogram without having to step through the whole main program Since DB executes all subprograms up to the specified filename all external subprograms encountered must be com
34. The elements after the variable name are optional depending on the kind of variable you are defining For example if you are defining an array variable you include the optional number specifying the dimension in the MAP statement We ll discuss each of these optional elements in detail in the following sections AlphaBASIC PLUS User s Manual Rev 02 Mapping Variables Page 14 3 If you skip an element in the MAP statement for example you want to specify the value but not the size you must keep the comma showing where the missing size should be For example MAP1 NEW VARIABLE F 23 The MAP statement may not end with a comma If you don t specify any of the optional elements do not use any commas The MAP statement above defines NEW VARIABLE assigns it the data type F for floating point does NOT specify a size which becomes the default size 6 if an AMOS variable 8 if the program is compiled with l selecting IEEE variables and assigns it the initial value of 23 Without the extra comma BASIC thinks you were trying to assign a size of 23 bytes to NEW VARIABLE an illegal operation for a floating point variable 14 2 1MAP Level E The number following the MAP statement MAPn represents the level of the mapped variable lt must be within the range of MAP1 through MAP16 MAP statements are hierarchical in nature For example a variable mapped with a MAP1 st
35. The value 1 represents a 40 bit mask of all ones Any relational comparison between two AlphaBASIC PLUS User s Manual Rev 02 Expressions and Evaluation Page 7 5 expressions or variables returns 1 if true or 0 if false 6Jf two strings are of equal length they are compared on a character by character basis If they are of different length the shorter is padded with spaces on the right to the length of the longer and then the comparison proceeds Thus the string PAST DUE is equal to the string PAST DUE 7When conversions are done for example from real to integer any data outside the limits of the destination variable is merely lost without an error being raised Range checks are the responsibility of the programmer Converting from real numbers of any format to integers is done by truncating the value towards minus infinity Therefore 12 9 will be converted to 12 12 9 converted to 13 and 12 1 converted to 13 This is the behavior of the INT function as well The FIX and RNDN functions can be used to produce a slightly different results INT N FIX N RNDN N 8When converting from negative values to binary variables AlphaBASIC PLUS stores the signed integer result in the binary variable by doing a simple byte move As the sign bit of an integer value is the most significant bit in the value this has the result of making the value of the binary number a very large positive value as that same bit is treate
36. To use the debugger you must compile the source program with D For example COMPLP test D Eta This produces the RPD file used with the debugger 22 2CALLING THE DEBUGGER Enter DB and the name of your file the default extension is RPD For example DB test EUN 22 3WHAT YOU SEE When you enter the debugger you will see your program much like if you were editing it Some things will be different though For example in IF THEN statements where no labels exist you may see a GOTO statement followed by a number This is the debugger s way of marking where the program goes next the number is a byte offset AlphaBASIC PLUS User s Manual Rev 02 Page 22 2 22 4CONTROLLING PROGRAM EXECUTION Chapter Twenty Two Here are the key sequences you can use with DB and what they do CONTROL FUNCTION NEXT SCREEN PREV SCREEN Cursor down one line Cursor up one line Screen down one page Display initial screen Cursor to previous label screen not on current Cursor to previous label Executes lines from home position to current cursor location If the cursor is on a line that has already been executed the whole program is executed and a breakpoint is set on that line Proceed Move cursor to current program pointer Redisplay screen Executes current source line Executes a subroutine or function from call point subprogram Tog
37. code is a number representing the thing you want the version of from these choices 0 The version of the currently executing file 1 The version of RUNP LIT that is executing this file 2 The version of AMOS in memory 3 The version of the compiler that compiled this file 4 The date this program was compiled in internal format E 5 The time when this program was compiled in separated format This information is available only if the file was compiled with the R switch If R was not used these values return a null string Notice that the date and time are returned as string variables not integers A positive number for the code represents the memory address of a PHDR of a program and returns the version number of the program at that address The version number is actually 2 bytes past the start of PHDR but you need to specify PHDR for the address to be correctly returned PHDR is set by the PROGRAM statement The format of PHDR is described in Appendix A of the AMOS Monitor Calls Manual AlphaBASIC PLUS User s Manual Rev 04 CHAPTER 12 FORMATTING OUTPUT Most business applications programs spend a great deal of effort in generating reports and printouts in which data must be neatly and clearly presented In other words correctly formatting output is usually a major concern of the programmer AlphaBASIC PLUS has several features that help you format data This chapter discusses eHow to use the USING modifier to format dat
38. familiar with error trapping explained in Chapter 17 because error trapping is a necessity for ISAM PLUS programs This chapter also assumes you are familiar with the Alpha Micro ISAM PLUS system which is fully explained in your ISAM PLUS User s Guide This chapter is intended as a quick reference guide to the ISAM PLUS commands used within AlphaBASIC PLUS more detailed information about using ISAM PLUS from AlphaBASIC is in your ISAM PLUS User s Guide 19 2ISAM PLUS FILE STRUCTURE ISAM PLUS files are more complex in structure than sequential or normal random files allowing large data files that can be accessed faster and more precisely Both the INDEXED and INDEXED EXCLUSIVE modes of ISAM PLUS require the ISAMP program be able to write to the disk containing the index files even if you do not plan to do anything more than read from the disk Therefore make sure the disk containing the index files is not write protected 19 3UPDATING THE RECORDS OF AN ISAM PLUS FILE This section describes the statements for positioning the file pointer reading writing adding deleting locking and unlocking the records of an ISAM PLUS file Each description includes the FORMAT defining the syntax of a particular verb and the COMMENTS explaining the parameters variables trapped errors and status values The GET GET NEXT and GET PREV verbs with the qualifier LOCKED allow you to locate read and lock a record all in a single statement True l
39. o o 1 4 Binary variables 1 4 14 6 Floating point variables 1 4 14 6 Integer variableS o 1 4 Simple variables 1 4 String variables 1 4 14 5 Unformatted variables 1 4 14 5 Data types noi ide Rd 8 3 Default soria Dira ra een EO 6 13 Dales aaa aa ar aS c di 10 13 11 2 DATING SS ante ce bte se e 10 4 po 22 1 Command mode 05 22 3 Key sequences oooooooooomoo 22 2 Screen mode ususuus 22 3 DB commands E A E RS 22 4 OD olet oculus peg ee eRe hides 22 4 AS 4 eI cua eC E EE 22 5 ATTAGH S ree Trete ode bead oc 22 6 BREA Raider e cose Bis RE 22 4 CHAIN Mm 22 9 CHANNEL osos chaos ate and a8 22 6 CIGAR drerit Ede eret ies 22 4 ERR cese ta 22 6 A e oun Rea 22 6 FUNCTION ecvccesseetiethe heat es 22 7 Page Index 4 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index INDENT 5nd oru E ES ED LEAEPxSS 22 7 LABELS ea reee 22 7 EET ei Mentre RENE d 22 7 NEWS ndo tel eek edna ii a 22 8 PROCEED 2 0 es oed ced fe 22 8 QUT ois ao Rts Sd ie ep IS PERS 22 8 REMOVE 2 ais Ba ae cide eee 22 8 RESUME 23 malt tetera tattered eae 22 8 AUN te SER As o iO Oe Bo 22 8 SCALE ara dan eae 22 8 SEARCH tos kota paca ee oa Ed 22 5 SIGNIFICANCE coco isos 22 8 SUBPROGRAM sica pra 22 9 TRACE vLex e dac libere ed 22 9 TRAP Sas ate ternis nre ud 22 5 UNTRACE aaa 22 9 UNTRAP Ses tete e
40. other disk files to access and store data In many applications using disk files is much more efficient and versatile than using user input or DATA statements to obtain data And it is the only efficient way to store data for later reference AlphaBASIC PLUS supports two kinds of data files sequential access and random access disk files You may write data either in ASCII characters or in packed binary formats Files created by AlphaBASIC PLUS programs are compatible with all other system programs and AlphaBASIC PLUS files may be interchanged with files from other languages That is AlphaBASIC PLUS data files can be read and manipulated by programs written in other languages Conversely files created by other languages and system utilities may be read and manipulated by programs written in AlphaBASIC PLUS Since the I O processes differ somewhat between sequential and random data files we discuss sequential and random files at a general level before getting into the specific commands you can use to work with these files AlphaBASIC PLUS User s Manual Rev 02 Page 15 2 Chapter Fifteen 15 2FILE CHANNELS All references to a file are made by specifying a file channel number which may be any variable or literal that evaluates to a positive integer value from 1 to 65 535 You might think of the file channel number as a pipeline between your AlphaBASIC PLUS program and the data file through which data can be transferred File channe
41. versions As an example take two hypothetical versions of COMPLP and RUNP version 10 0 600 which implements the ABC compatibility option and version 10 0 606 which also implements the XYZ option eRule 1 You cannot specify an option in an RP or SPG file unless the version of COMPLP you are using supports that option In our example you cannot specify the XYZ option to COMPLP 10 0 600 it will throw an error If you use a version of COMPLP prior to 1 0 267 the P and PX command line switches are not recognized nor is the PRAGMA FEATURE command so the appropriate information cannot be put into the RP or SPG file eRule 2 Unspecified options are not set In the example if an RP is produced with the ABC option by COMPLP 10 0 600 and run by RUNP 10 0 606 the ABC option is set but the XYZ option is cleared by definition eRule 3 If you select an option and later run the file under a version of RUNP that does not have the option defined RUNP will throw an untrappable error when loading the file and will not execute it In the example if an RP is produced by COMPLP 10 0 606 with the XYZ option set and run by RUNP 10 0 600 that version of RUNP will see an option that it knows nothing about display an error message and abort to AMOS command level without executing any part of the file Rule 4 is an exception to this rule eRule 4 The exception to Rule 3 If an executable file is created with any option selected a
42. 1 IF X gt 0 THEN EXIT INPUT 1 A TEST NUM TEST LOOP UNTIL EOF 1 NUM TEST NUM TEST 1 You may also use REPEAT statements see below to transfer control to the DO test 9 11ECHO Echo means you see the characters you type on the keyboard on your terminal screen This is the normal condition You only need to use ECHO if you have turned off the echo by using NOECHO see below The format is ECHO 9 12ELSE See IF THEN and ELSE below 9 13END The format is END END causes the program to terminate execution END doesn t terminate compilation of the program nor is it required at the end of the program If other program statements follow the end of the program e g subroutines terminating the program with END prevents your program from incorrectly entering those statements and executing them A program may have more than one END statement 9 14ENDSWITCH See below SWITCH and CASE AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 7 9 15EXIT Used inside a loop structure FOR NEXT DO LOOP SWITCH etc or a function to exit from the loop or function regardless of what the condition evaluates to Control passes to the statement after the loop terminator For example FOR I 3 TO 100 Last INT SOR 1 FOR Factor 2 to Last IF O I Factor INT I Factor THEN EXIT IF A lt 0 OR A gt 100000 THEN EXIT NEXT Fa
43. 14 DIV 5 14 DIV 5 14 DIV 5 14 5 by Ho Y HOYA Il In the first case the operator is evaluated first 14 5 uses the floating point operator requiring conversion to floating point for 14 and 5 and then the division yields a floating point result 2 8 The two results are then added together as floating point number yielding 5 6 The result of the expression is thus a floating point number of value 5 6 To store this in a four byte integer the value is truncated towards minus infinity yielding the answer of 5 being stored in I In the second case the DIV operator is evaluated first 14 DIV 5 uses the integer operator resulting in an integer result of 2 Integer 2 is then added to integer 2 yielding an integer result of 4 which is directly stored in I AlphaBASIC PLUS User s Manual Rev 02 Page 7 8 Chapter Seven In the third case the DIV operator is evaluated first giving an integer result of 2 Then the operator is evaluated giving a floating point result of 2 8 To do the addition the integer 2 is converted to the real number 2 0 using the convert to the wider operand rule and a floating point addition to 2 8 is done yielding a floating point result of 4 8 This is converted by truncation towards minus infinity to integer 4 and is stored as the value in I 7 8THE SIGNIFICANCE OF SIGNIFICANCE The SIGNIFICANCE program statement is discussed in Chapter 9 In brief it has nothing whatsoever to do
44. 16 2 4 1Subprogram Name For external subprograms the SUBPROGRAM statement must be the first line of executable code in the file Blank lines comments and PRAGMAs can be placed before the SUBPROGRAM statement For internal subprograms the SUBPROGRAM statement must be placed after the last executable statement of the main program A SUBPROGRAM statement stops the compilation of the main program and starts the compilation of the subprogram Therefore all the main program statements must have been compiled before a subprogram is started The name must be six alphanumeric characters or less For internal subprograms this name is the name used in SUBCALL statements to execute the subprogram For external subprograms this name used for error reporting and documentary purposes only It is not the name used in a SUBCALL statement the name in the SUBCALL statement is the filename without an extension of the SPG file that contains the subprogram 16 2 4 2Parameters You can declare formal parameters for a subprogram by using PARAMETER statements which work just like MAP1 statements A PARAMETER may have lower level MAP statements below it For example SUBPROGRAM TaxAdd PARAMETER Base Income MAP2 Deductions F 6 MAP2 Depreciation F 6 PARAMETER Tax Rate MAP2 Base Percentage F 6 MAP2 Clause_13_deduction F 6 This defines a subprogram called TaxAdd with two parameter
45. 2 so FNB returns 3 The value of bindings are determined dynamically in AlphaBASIC PLUS based on how the program runs rather than how it might look on paper ECHO A response by the computer to what you press on the keyboard If you press a key say C and you see a response on your terminal screen an a appears then your computer is in ECHO mode the normal mode Sometimes for instance when you are entering a password the computer echoing can be turned off so what you type goes to the computer but isn t displayed on the screen AlphaBASIC PLUS User s Manual Rev 02 Page 4 EXPONENT EXPRESSIONS FILE LOCKING FLOATING POINT NUMBER FORMAL PARAMETER GLOBAL VARIABLE Glossary If a number has more digits than AlphaBASIC PLUS usually displays the number is displayed in scientific notation a number expressed as a factor of ten For example 5 000 000 is expressed as 5E10 6 The E indicates the number is in scientific notation and the 10 6 indicates how many zeroes must follow the 5 The value 6 is the exponent A portion of AlphaBASIC PLUS syntax that can contain variables constant values operator symbols functions or combinations of these things Expressions are not complete AlphaBASIC PLUS statements but make up parts of AlphaBASIC PLUS statements For example X SIN SOR Number Everything to the right of the equal sign is an expression and the expression combines with the X to form an Alp
46. 5 12Print Information on All File Channels FILE prints information on all currently open file channels For example gt FILE EN Channel number 3 Filespec ACCT DAT Open mode OUTPUT Channel number 2 Filespec INVEN DAT Open mode INPUT Channel number 1 Filespec EMPLOY DAT Open mode APPEND If no files are open there is no display AlphaBASIC PLUS User s Manual Rev 02 The AlphaBASIC PLUS Debugger Page 22 7 22 5 13Display Function Source Code FUNCTION displays the source code starting at the specified function or the first function if none is specified and continuing until the end of the file The format is FUNCTION function name 22 5 14Indent Text INDENT sets the number of spaces the debugger indents your program text This is useful if your current program indentation is too close to read easily or too deep to fit on the screen The number can be from 1 to 10 For example gt INDENT 5 22 5 15Display List of Labels LABEL displays a list of labels starting from the specified label or the start of the file if no label is specified along with the label s object code offset the number of bytes from the start of the file Labels with a break point set on them are displayed in reduced intensity if your terminal supports this feature The labels are listed in program offset order For example gt LABEL First List EUN First List 00001396 Credit Rating 00001412
47. 9 Listing a program iocos ee b RE 3 7 Loading programs 4 3 Prompt rsd satus este set PER Est 3 2 Running a program 3 8 Saving programs Ls 3 5 Single step La 4 4 Stopping a program run 4 3 Interactive prompt o o 3 2 Interrupting programs 4 3 5 11 o A tecto ulus dido ard uda ed 11 2 ISAM TSS ac Sa teed od Deen estet door 15 7 ISAM PLUS s edd oe rn 19 1 ALLOCATE INDEXED 19 8 CLOSE sio cad box La iid 19 7 CLOSER Locri es 19 7 GREATE REGORD eee 19 6 DELETE RECORD ca a ees 19 6 Error processing 2206 cee n 19 9 File structure uu ex a 19 2 FIND GS core Ede Di pd 19 5 FIND NEXT Lu odere tentus demde es 19 5 FIND PREV ssh Lita cris 19 5 GET oru eg os ata 19 3 GET LOCKED 55i RR RR 19 3 GETNEO T etit htt rn d 19 4 GETNEXTLOCKED 19 4 GET NEXTREAD ONLY 19 4 GET PREY stein oros 19 4 GETPHEVLOONKED uxores hes 19 4 GETPREV READ ONLY 19 4 GET READONLY 52 Lene esas 19 3 INDEXED STATS er Id ere d 19 8 OPEN ua se P eS rs 19 3 RELEASE ALIS oa ie aie Ries 19 7 RELEASE REGORD cui died ane See 19 6 UNLOKR 20 og ite nte Ere sr Ot 19 7 UPDATE RECORD coccion 19 5 ISAM PLUS statistical information 19 8 ISAMIKEY onto AERE 19 3 ISAMP BPI include file 19 2 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index ISO Latini ito aras F 1 Key
48. ART adt d 22 4 ome 14 8 14 13 22 4 o MP E 2 Ju s ciel me Bee ant E SE AN E 2 AlphaBASIC PLUS User s Manual Rev 02 Page Index 1 INDEX AlphaBASIC PLUS User s Guide Index Accessing random files Account specification ACS data rbd DS to ae ade ALLL OCAT Bex cnet Bitrate qua Mein ale ALLOCATE INDEXED AlphaBASIC PLUS AlphaBASIC search path Alphabetic characters Alphanumeric characters AlphaXED ess eres Alternative radix constants AMOS A cet os ee a AMOS statement Switches Ampersand symbol 8 AND aS rate Ree Cee ae Apostrophe APPEND mode Argument list format Arguments Pass by reference Pass by value Arithmetic stack Array variables Default size ASNO us cria tos Assembly language subroutines Assigning a value AUTOS ite tg Ga ec hs tas ee obtu Atsign actin a Md ATTACH racer aes Automatic subroutine loading B A S I C what it stands for Base of natural logarithms BASICA oa sos anto e tpe Compiler BASIC search path BASIOB LIT x s a dee Binary data 2 hk LE Page Index 2 buses tos 10 4 P 14 6 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Inde
49. AlphaXED or the interactive mode in creating your program If you create and save your source program in interactive mode that program must contain line numbers otherwise the interactive interpreter assumes a direct statement AlphaBASIC PLUS User s Manual Rev 03 Page 5 2 Chapter Five The monitor level compiler COMPLP doesn t require a program to have line numbers That means if you create your program using AlphaXED you don t need line numbers In addition you may indent your program lines in any way you like By omitting line numbers and using labels and by using indentation judiciously you can make your source program easier to read A label is a special name defined by you that identifies a location within a program Although COMPLP doesn t require your program to have line numbers it does check for duplicate line numbers within your file Even when the O switch is in effect the compiler reports duplicate line number errors It does NOT however check for lines out of numeric order See below for information on the O option The compiler also allows the use of statements that start on one line and continue on to another line These are called continuation lines and are discussed in section 2 4 For example IF Answer Right Number THEN PRINT Very Good amp ELSE amp PRINT Try again As you may have noticed the above example is only one AlphaBASIC PLUS statement even th
50. BREAK BYE BYTE CALL CASE CHAIN CHR CLOSE CLOSEK CMDLIN COMPILE COMPLP CONT COS CTRLC CREATE RECORD DATA DATE DATN DEF DEFAULT DEFINE DELETE DELETE RECORD DIM DITOS DIV DIVIDE BY O DO DSTOI ECHO EDIT ELSE END ENDIF END FILE ENDFN ENDSELECT ENDSWITCH EOF EQV ERF ERR ERROR ERRMSG EXIT EXP EXPAND FACT FILEBASE FILEBLOCK FILL FIND FIND NEXT FIND PREV FIX FMOD FN FN FOR GET GETKEY GETLOCK GET NEXT GET NEXT LOCKED GET NEXT READ ONLY GET PREV GET PREV LOCKED GET PREV READ ONLY GET READ ONLY GO GOSUB GOTO IF INDEXED INDEXED EXCLUSIVE INDEXED STATS INPUT INSTR INT 10 ISAM ISAM INDEXED ISAM INDEXED EXCLUSIVE ISAMP INDEXED ISAMP INDEXED EXCLUSIVE KILL LCS LEFT LEN LET LINE LIST LOAD LOCK LOG LOG10 LONG LOOKUP LOOP MAP MAX MEM MID MIN MOD NEW NEXT NO DIVIDEBY ZERO NOECHO NOEXPAND NOT ODTIM ON OPEN OR OUTPUT PARAMETER PRINT PROGRAM RANDOM FORCED RANDOM RANDOMIZE RAW READ READ ONLY READ READ ONLY READL RELEASE RECORD RELEASE ALL REM RENAME REPEAT RESTORE RESUME RETURN RIGHT RND RNDN RUN RUNP SAVE SCALE SELECT SGN SIGNIFICANCE SIN SLEEP AlphaBASIC PLUS User s Manual Rev 02 Page B 2 SPACE STEP STRSIZ SUBPROGRAM TAN UNLOKR VAL WHILE WRITEL SPAN BLOCKS STOP SUB SWITCH THEN UNTIL VER WORD WRITEN SQR STR SUBCALL SYSCALL TIME UPDATE RECORD WAIT FILE WRITE XCALL Appendix B STATS MAP STRIP SUBEND TAB TO USING WAIT RECORD WRITEL XOR AlphaBASIC
51. CODE and one floating point variable PRICE The origin parameter in statement 300 also causes this area to overlay the INVENTORY area exactly AlphaBASIC PLUS User s Manual Rev 02 Mapping Variables Page 14 9 Overlaying allows variables to be referred to in a different format than when they were entered into memory Make sure your program is reading the correct variables at the correct time 14 3USING MAP STATEMENTS MAP statements can be used as direct statements in interactive mode as a learning tool to see how variable mapping works Interactive mode also gives you immediate feedback if you enter the MAP statement incorrectly making it easier to learn the MAP syntax MAP statements are not designed to be practical in interactive mode however and are best used by putting them into a program file and compiling the program MAP statements should come at the beginning of the program and must come before any references to the variables being mapped If you refer to a variable before it is mapped such as A 5 8 the variable is set up according to AlphaBASIC PLUS defaults When the MAP statement is reached it then returns an error since the variable is already defined Remember the COMPLP program offers a M switch that reports unmapped variables in your program useful if you want all your variables to be mapped It is also helpful in preventing misspellings of variable names which can be a hard to find program error 14 3 1
52. DAY EUN 7 HAVE A NICE DAY AlphaBASIC PLUS prints a carriage return linefeed after expression list unless it ends in a comma or semicolon Remember an expression may consist of a string or numeric variable numeric constant string literal or constant function with arguments operator symbols or a combination of these elements For example the following is one string expression AlphaBASIC PLUS User s Manual Rev 02 Page 9 22 Chapter Nine STRING DATA NAMES MIDS AS 1 2 AlphaBASIC PLUS displays numeric data with a trailing blank It also prints one leading blank if the number is positive lt does not print a leading blank if the number is negative AlphaBASIC PLUS displays string data with no leading or trailing blanks You may place more than one numeric expression after the PRINT keyword if you separate them with commas or semicolons If you separate the expressions by semicolons AlphaBASIC PLUS does not print extra spaces when it prints the evaluations of those expressions For example 2 12 12 32 8 2 prints 24 32 4 There are no blanks between the numbers above except for the normal leading and trailing blanks displayed with numeric data String expressions may be separated by blanks semi colons or commas Semi colons blanks are the same as semi colons cause the elements to be printed with no spaces between them For example DAYS Monday RETA PRINT Status Report DAYS tm
53. Employee List ENDIF Note the expression evaluated by the IF statement usually contains relative operators e g IF A B IF A gt 0 etc However it may be any legal expression For example A 0 i B 1 IF B THEN PRINT B is not zero IF B AND A PRINT nonzero numbers amp ELSE PRINT at least one zero number 9 20INPUT The format is INPUT prompt string varl var2 varN Allows data to be entered from your terminal and loaded into specific variables at run time The INPUT statement contains one or more variables separated by commas If you omit the prompt string AlphaBASIC PLUS displays a question mark on the terminal display to signal a request for data entry For example INPUT A EUR 7 5 RETURN PRINT A EUN 5 If you use a prompt string AlphaBASIC PLUS displays it instead of a question mark to prompt the user of your program for data If you wish to have no prompt at all use a null prompt string as in INPUT A B prompt string must be in the form of a string literal enclosed in quotation marks For example INPUT Enter your account number ACCOUNT NUM prints Enter your account number AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 15 You may specify integer floating point and string variables in an INPUT statement INPUT accepts the E and D exponent mark
54. FILE This section shows how to create indexed files from within AlphaBASIC programs using the ALLOCATE INDEXED statement and the ALLOCATE MAP structure It also shows how you construct the map structure using the templates provided in the file BP CREATE BP 19 4 1ALLOCATE INDEXED This statement tells ISAM PLUS to create the named file using the parameters stored in the ALLOCATE MAP structure you have prepared The format is ALLOCATE INDEXED filespec ALLOCATE MAP device ALLOCATE MAP specifies the MAP structure which defines the file parameters There is a file called CREATE BP in BP DSKO 7 35 This file can be used to make a template for creating an ISAM PLUS file structure tailored to your needs See your ISAM PLUS User s Guide for more information Device is the device on which where you want the data IDA file created If you do not include device both the index IDX and data IDA files are created in the current account 19 5RETRIEVING STATISTICAL INFORMATION This section shows how to retrieve information about an ISAM PLUS file using the INDEXED STATS statement and the STATS MAP structure It also shows how you construct the map structure using the templates provided in the file BP STATS BP 19 5 1INDEXED STATS There are two different syntax notations for INDEXED STATS Each causes the statistical information to be gathered in a different way They are INDEXED STATS fil
55. File Input Output System Page 15 11 Any INPUT statements which reach end of file return numeric zero or null string values for each subsequent INPUT statement This means the normal sequence for processing sequential input files is to INPUT the data into the variables and then test the EOF X status before actually using the data in those variables since if an end of file has been reached that data is invalid End of file should only be tested for sequential input files Files open for output or for random processing always return a zero value 15 9 5FILEBASE During normal operation AlphaBASIC PLUS refers to the first record in a random file as record number zero i e you set the record number variable to zero to access the first record in the file In some applications you may want AlphaBASIC PLUS to refer to this first record by some number other than zero for instance to allow you to use zero to flag some special condition such as a deleted record The FILEBASE command allows you to set the number used to refer to the first record For example FILEBASE 1 tells AlphaBASIC PLUS the first record in the file is record number one not record number zero You may use any numeric argument with FILEBASE and the value may be a variable Floating point numbers are converted to an integer value Note FILEBASE does not associate its value with a single file it affects all files in the program but only takes effect when
56. Letter With Lu Grave 315 205 CD Latin Capital Letter With Lu Acute i 316 206 CE Latin Capital Letter With Lu Circumflex 317 207 CF Latin Capital Letter With Lu Diaeresis D 320 208 DO Latin Capital Letter Eth Lu N 321 209 D1 Latin Capital Letter N With Lu Tilde 322 210 D2 Latin Capital Letter O With Lu Grave 323 211 D3 Latin Capital Letter O With Lu Acute AlphaBASIC PLUS User s Manual Rev 02 Character Sets Char Also Octal acter Called Value 324 325 326 x 327 330 U 331 332 333 334 Y 335 b 336 B 337 340 341 342 343 344 345 346 347 350 351 352 353 i 354 355 356 i 357 0 360 361 Decimal Value 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 Hex Value D4 D5 D6 D7 D8 D9 DA DB DG DD DE DF E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 EA EB EC ED EE EF FO F1 ISO IEC 10646 1 1993 E and Unicode 2 0 Name Latin Capital Letter O With Circumflex Latin Capital Letter O With Tilde Latin Capital Letter O With Diaeresis Multiplication Sign Latin Capital Letter O With Stroke Latin Capital Letter U With Grave Latin Capital Letter U With Acute Latin Capital Letter U With Circumflex Latin Capital Letter U With Diaeresis Latin Capital Letter Y With Acute Latin C
57. Mpio rt pas 10 12 Keyboard echo iocos Re 9 6 Qi FINDS EI 11 5 15 14 LABEL S anas Srt as dace 22 7 LADES a e t ice atte te ed des 1 4 2 2 5 2 Largest integer lt a number 10 3 LOS ADY Las cae lis 10 7 Leading blanks 9 22 Leaving a loOp sx rs 9 7 LEERTE 10 7 Left relative position 8 2 LENTA ss regar a teas 10 8 Length of strings 10 8 EET voe tue ee de Dead oh 9 18 22 7 Library account 354 e 50 1 id es 18 1 Library Searching oo o o o 2 4 Line editing d AN See tes oe su es 3 4 Line numbers 00 cece eee 2 1 3 4 5 2 Linefeed key 0 00 cee eeee 4 4 Bl 3 7 Listing an interactive program 3 7 Literals 4e Rev eR EEIRSRCEREREX A4 6 10 Alternative radix 6 11 Character AAA a A M ee 6 10 Floating point soo cmi 6 12 ire TES Cp e ER 6 10 sig ria a pd 6 12 EQUI e ad s 4 3 5 3 Loading a program into memory 3 4 4 3 Loading files into system memory 1 3 Local variable list 20 2 Locating open subroutine files E 4 LOCKING a file 5 2 cde eR a da 19 6 LOGIA oido adas 10 3 LOGIDOS sean ER ER Ys 10 3 LOGAN ir 10 3 Logarithm decimal 10 3 Logical OperatorS 7 2 AI ON METTE 7 2 A A nal nen hie Ne 7 2 A sa Oe Gee iE et 7 2 ORs rm 7 2 KOR rM 7 2 Logical records cer RR 15 5 EONGUN pia E CO ER ERE Ne
58. PLUS User s Manual Rev 02 APPENDIX C PROGRAMMING HINTS In this appendix we explore a few ways to make your programs more time and memory efficient We discuss eManaging memory eincreasing execution speed eincreasing readability of program source files C 1MANAGING MEMORY AlphaBASIC PLUS uses memory to store the variables you use within your program It also uses memory space for calculations Here are some hints for reducing your program s use of memory eWhen you allocate arrays and or strings give them only as much memory they need and no more Allocating an array to 50 when you only need 10 subscripts wastes a lot of memory eUse MAP statements if you have a large number of strings varying in size By doing this you can allocate each string individually rather than setting STRSIZ to the size of the longest variable and wasting space for all the shorter variables MAP statements generally help reduce memory use eUse as few variables as possible Using one scratch variable that can be reset as needed instead of a number of individual variables can help eDo not rewrite sections of code that are used more than once If you have ten lines of code used in more than one place make those lines a subroutine or user defined function The more lines in the program the more memory used An additional benefit is there is only one routine to modify if changes become necessary eWhere possible MAP variables into the same st
59. ROCA 9 14 9 21 INPUT MAINE ae sis pai a A ERA eR C ce ce dte e 9 17 922 INPUDRAW acie ait a ther a ER EZ ep eat ce nex d acide aca Ac 9 18 9 23 LED TII cR 9 18 cw Rea TREE 9 19 9 05 NEXT a MS coke DU tet iR scar Sra d S iue AE io cite de Ap 9 19 9 26 NODIVIDE BY O Sata sar desde 9 19 AlphaBASIC PLUS User s Manual Rev 04 Page iv Table of Contents O e LE o RE ME 9 19 9 28 ON CTRLC GOTO AND RESUME s ses 9 19 9 29 ON ERROR GOTO AND RESUME 0 0e0cs eee eees 9 20 9 30 ON GOSUB CALL cr ate Ure e EE ta anes Rae 9 20 9 BION GOTO oes Museo Lora ea Pep a OA a lg IE 9 21 IE OI PPRO AME 9 21 9 33 PRINT USING ataca tre veh rS INC tae DERE AES 9 23 9 34 PROGRAM ici euren debi IR CAT Rods th uo o n 9 24 9 35 BANDOMIZE a TR ANA E eR 9 24 9 36 READ RESTORE AND DATA sss es 9 25 9 37 RENAME ri ps en dai nt d va RT RAN Tan 9 26 A ies E S ah AU te ction Ada 9 26 930 RESTORE ctra te onte nm tenis cada dite 9 27 9 40 RESUME x0 92 tus Desain ceder ea i t eevee aves 9 27 9 41 RUE TURN A A ne alah pelos Races etre Pd eio fa 9 27 GAS SCALE ono eie cg NK E e ELM M tales a E 9 27 943 SIGNIFICANCE tot e Br e p on 9 27 9 44 SEER E ex o hens mot reise to esses M eu ERE 9 28 e IA A IS 9 28 OB STOR A E 9 29 SEE AN A A O S 9 29 S48 SWITCHIGASB cob cicero tea niae ek Cade ov ate d 9 29 E euch A Lr eise EAE EN E 9 31 v3 moro AR ERE IS EC UAE WE CERA 9 31 Dd UN tg e ossi AA LA OE dt 9 31 GBP DSINGI sestertia eee Combo ar
60. Statements Page 9 21 9 310N GOTO The format is ON expr GOTO label line 1 label line 2 label line N The ON GOTO statement allows multi path GOTO branching to one of several points within the program based on the result of evaluating the expr expression expr can be any valid expression which is evaluated and truncated or rounded if IEEE to a positive integer result The result is then tested to branch to label line 1 if 1 label line 2 if 2 etc If the result is zero negative or greater than N the program falls through to the next statement The following is a portion of a menu selection program PRINT TAB 22 Select One of the Following Operations PRINT PRINT TAB 25 1 Insert Edit NAME Information PRINT TAB 25 2 Insert Edit PHONE NUMBER Information PRINT TAB 25 3 Quit without insertion or editing PRINT INPUT Your choice 1 20r 3 A ON A GOTO NAME PHONE QUIT NAME INPUT Select a name N The program continues with all three alternatives At the end of the program section called by the GOTO an END or another GOTO may be used to keep the program from executing other portions of program code 9 32PRINT Evaluates and displays on your terminal the expressions you specify The format is PRINT expression list Or expression list For example PRINT 3 4 HAVE A NICE
61. User s Manual Rev 02 CHAPTER 21 THE UNIFY RELATIONAL DATA BASE MANAGEMENT SYSTEM RDBMS INTERFACE The Unify Relational Data Base Management System is explained in the UNIFY Reference Manual This chapter discusses eWhat is UNIFY eThe UNIFY XCALL a quick reference 21 1WHAT IS UNIFY UNIFY is a relational data base management system It allows you to create and modify application systems that store and retrieve data Using AlphaBASIC PLUS you can access and manipulate the data in a database using the Host Language Interface functions UNIFY provides 21 2UNIFY XCALL FORMAT The general format for the call is XCALL UNIFY function status variable parameters where function is the UNIFY function you want to use status variable is a variable to contain information passed back from UNIFY and parameters are whatever data or specifications are required for that function All the functions are defined in the file BP UNIFY BPI DSKO 7 35 AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 22 THE AlphaBASIC PLUS DEBUGGER The AlphaBASIC PLUS debugger DB LIT is an interactive program that lets you debug a BASIC PLUS program at the source language level Functions variables and statements are referred to by the names from the original source file It lets you set breakpoints at statements view and change variable values and run the program on a statement by statement basis 22 1SETTING UP YOUR PROGRAM FOR DEBUGGING
62. Usually unformatted data is only moved to another unformatted variable or to or from an external device The move is done by copying bytes from one variable to another Any null bytes are transferred intact and do not terminate a copy unlike their behavior in a string operation Assigning other data types to an unformatted data type and back can give strange results and the round trip is not guaranteed to produce an unchanged value PRINTing unformatted variables to sequential files and subsequently INPUTing them also gives undefined results All these operations are not recommended unless you understand all the ramifications and are willing to deal with undocumented behavior 6 2 4Literals and Constants Literals can constants can have the following data types einteger also single character eFloating Point eString 6 2 4 1Integer Literals and Character Constants Integer literals or constants are written as whole numbers without a decimal point or exponent symbol Examples 12 19347563 72947756 Character constants can be used as expressions They are distinguished by enclosing a Value representing a single byte in single quote marks apostrophes They are equivalent to their corresponding code point ASCII value and are treated as true integers Examples are 97 rat E 65 27 E 90 A backslash can introduce a special value AlphaBASIC PLUS User s Manual Rev 02 Variables Page 6 11 r 15 13 a slash followed
63. You can use both numeric and string variables in arrays An array is a powerful way of storing and manipulating variable data An array consists of a set of ordered variables all under one variable name Each array variable consists of a standard variable name NUMBER plus a subscript NUMBER 1 The subscript tells you which variable within the array is being worked on For instance when you enter NUMBER 3 5 AlphaBASIC PLUS assigns the value of 5 to the 3rd element in array NUMBER ry Do not use 0 as the subscript number in an array it will cause an error The subscript number can also be a variable allowing you a lot of flexibility in handling arrays Here is a small program that fills an array with values For COUNT 1 to 10 AlphaBASIC PLUS User s Manual Rev 02 Page 6 14 Chapter Six NUMBER COUNT COUNT COUNT Next COUNT Using the loop control variable COUNT we ll explain FOR NEXT loops later on as the subscript variable allows us to fill the array with values The first time through the loop COUNT has the value of 1 so NUMBER 1 1 The second time COUNT 2 so NUMBER 2 4 2 times 2 And so on When you use an array variable a certain amount of memory space is allocated for that variable and its subscripts The default value is 10 that is you can have up to 10 subscripts If you want to have more than 10 or you don t need that many you can change
64. a 2 4 Efficiency gt 220 2 snark Dlites dto 3 9 C 1 Memory Management H 2 Memory mapping esses H 2 Memory overlays 14 7 Memory Requirements H 1 MIBOAD e s e cres eg 10 8 MIN ieu wer e ore eL bei e dr as 7 2 Minor revision NUMDeT 9 24 MOD tcs Ea idad AS 7 2 Mode independence 8 3 10 1 Monitor command level 1 5 3 2 Multiple line functions 20 2 Multiple statement lines 2 3 3 3 Page Index 12 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index Page Index 13 Nested loops 2 46 cic RE RR 9 8 NEW coire vat terna Pease ee Bc 3 3 22 8 NEXT x esty aon there cee eee ERES 9 7 9 19 NODIVIDE BY U pair 9 19 NOE GEO 20 iaa ea e da E e 9 19 NOTI osos A 7 2 Null strings ooooooooo 9 14 10 8 15 11 Numeric functions wa tte des 10 1 Numeric variables Arguments o oooooooo ee eee 10 1 Binay e cea aides d tated es SA a ai ot 14 5 CONOS OM se Y RYE ed 7 4 Floating point aussen sade aia 14 5 Fuhctlons unir aa Le a 10 2 Value of a string 10 4 QDISCECOUG ia oe eee ee 1 3 Object programs 2 00 1 3 3 6 3 8 5 3 Octal values 2 c248a Sdntoud ee eee es F 1 OOD TUM este cas elena aed Sade eri 10 13 ON GOTO eine fod bs eee Od Sire Rees 9 21 ON CALE s eii en e e e e xr Ru ask 9 20 ON CTRLC GOTO cR ERR 9 19
65. and device you are logged into 4DO files look in x 0 then in DSKO 2 2 CMD files look in x 0 To load the file into system memory where it may be accessed by all users on the system the System Operator must add the appropriate SYSTEM command line to your system initialization command file m To load a file into your user memory partition use the monitor level LOAD command Note also when you chain to a monitor command after the command has finished executing it returns you to monitor level rather than to your program If you want to perform a system command without exiting your program use the AMOS command see Chapter 9 16 2WHAT IS A SUBPROGRAM A subprogram is a melding of a separate AlphaBASIC PLUS program and a more involved form of GOSUB Subprograms are used for two primary purposes As a way to structure a large program eAs a way to share code between separate programs thus simplifying coding and program maintenance A subprogram is a self contained section of code usually performing one or more defined business tasks lt operates in a separate but linked environment from the AlphaBASIC PLUS User s Manual Rev 02 Page 16 4 Chapter Sixteen program or other subprogram that called it which exists only for the duration of the subprogram s execution This separate environment is a distinguishing feature of subprograms and is a logical extension of the GOSUB CALL and user defined function environment
66. as ISAM files regardless of the X switch RI Always use the correct mode when opening ISAM or ISAM PLUS files Opening an S gt ISAM PLUS file as an ISAM file or vice versa could lead to unpredictable and destructive results 15 9 12PRINT Once you open a sequential file for output you use a special form of the PRINT statement using the file channel assigned by the OPEN to write data to the file All the techniques available to you when you use the normal form of the PRINT statement which outputs to the terminal are also available for sending data to a file including PRINT USING for formatted data PRINT writes data to the file in the same format as it appears if you use PRINT to send the data to a terminal display i e if you left off the file channel number Here is the format for PRINT and some examples PRINT file channel expression list PRINT 1 A B C PRINT 4 USING AS A SQR A PRINT Q1 USING A1 10 PRINT 1 THIS IS A SINGLE LINE PRINT file number WRITE TO PRINT ZONES See INPUT above for the required format for data when reading data from a file If the file associated with the file channel number is not OPEN PRINTing to the file causes an error For more information on PRINT see Chapter 9 15 9 13READ The READ statement reads a selected logical record from an open random file The logical record which is tran
67. as the String Work Area or SWA The required size of the SWA for a given RP file is determined by the compiler COMPLP and passed to RUNP in the RP file The size of the SWA is reported by COMPLP s compilation statistics and the MEM 14 function at runtime COMPLP can make a reasonably accurate estimate of the size of the SWA needed to successfully execute the RP file But there are two cases where COMPLP does not have sufficient information to make an accurate guess eWhere SPACE or FILL are used with a runtime expression to define the size of the resultant string In such cases COMPLP will use a set value 132 bytes in version 1 0 269 in its calculations elf a user defined function or subprogram is called COMPLP cannot look inside a user defined function to see the maximum SWA size required for executing the call Such information may not be available especially if recursive calls are used Similarly subprograms are compiled separately but will share the same SWA as the calling RP file COMPLP will not attempt to guess a reasonable value for the SWA requirements for this statement If you find that you need to adjust the size of the SWA from COMPLP s estimate you can use PRAGMA compiler statements Three PRAGMA statements are available PRAGMA SET_STRWRK constant_expression PRAGMA EXTRA_STRWRK constant_expression PRAGMA ADD_EXTRA_STRWRK constant_expression constant_expression is a c
68. below it in the hierarchy For example when you refer to NAME you get the information in the variables LAST and FIRST As AlphaBASIC PLUS allocates the variables NAME and ADDRESS it automatically includes them and their sub variables within the variable PATIENT INFO The MAP statements for the variable group above might be MAP1 PATIENT INFO MAP2 NAME Patient s name MAP3 FIRST S 15 MAP3 LAST S 20 MAP2 ADDRESS Patient address MAP3 STREET 5 30 MAP3 NUM S 10 MAP3 CITY S 30 MAP2 INSURANCE B 1 Flag if patient has insurance 14 2 2Variable Names in MAP Statements The variable name is the name your program uses to refer to the mapped variable it must follow the rules for AlphaBASIC PLUS variable names described in Chapter 6 However since you may specify the type you do not need to follow a string variable with a dollar sign or a four byte true integer with a percent sign If the variable name is followed by a set of subscripts within parentheses the variable is assigned as an array with the dimensions specified by the subscripts just as if a DIM statement had been used For example the statement MAP1 NUMBER F 6 assigns a single floating point variable called NUMBER but the statement MAP1 NUMBER 5 10 F 6 assigns a floating point array with 50 elements in it 5 x 10 just as if the statement DIM NUMBER 5 10 had bee
69. bytes each that define logical records and you never use these variables at the same time By defining the variables so they occupy the same area of memory your program only uses 256 bytes for the variables instead of 768 bytes Origin overlays may not work properly if your mapped variable is an array We recommend you don t overlay array variables Normally a MAP statement causes allocation of memory to begin at the point where the last variable with the same level number left off The origin parameter allows this to be modified so allocation begins back at the base of some previously defined variable and therefore overlays the same memory area If the new variable is smaller than the previous one or the exact same size the value of the new one is totally contained in the previous variable AlphaBASIC PLUS User s Manual Rev 02 Page 14 8 Chapter Fourteen If it is larger than the previous one it spills over into newly allocated memory or possibly into another variable area of the same level depending on whether there are more variables following The origin parameter must be the last parameter on the line It takes this form an symbol followed by the name of the previously mapped variable whose area you wish to overlay This variable must be on the same level as the variable you are presently allocating If size and value parameters are not included in this statement you may omit them with no dummy commas For example MAP1 CUS
70. can be KlLLed The switches are only in effect if no account or disk is specified in the LOOKUP command There is also a LOOKUP function see Chapter 11 15 9 110PEN You must open a file before you can transfer data to or from it The OPEN statement assigns a unique file channel number to a file and also specifies the name either to be given to an output file or to be used in locating an input file The format is OPEN file channel filespec mode record siz crecord variable SPAN BLOCKS WAIT FILE WAIT RECORD READ ONLY The elements of the OPEN command are file channel Any numeric expression which evaluates to a positive integer 0 is defined as the user terminal and treated as such Random files cannot use 0 as the file channel filespec Any string expression up to 48 characters long which evaluates to a legal file description May be a string or literal String literals must be in quotes mode The mode for opening the file See below AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 17 Record size An expression which dynamically specifies at run time the logical record size for read write operations on the file Not for Sequential files Random files may have their size specified on creation If you are accessing a file that already has a size the record size variable must specify the same size as the existing file If the file does n
71. can specify many of the switches used with the AMOS level COMPLP command when you enter the BASICP command These switches are then in effect for the entire interactive session For example BASICP I EUN To leave interactive mode and return to AMOS enter BYE AlphaBASIC PLUS User s Manual Rev 02 Interactive Mode Page 3 3 3 2DIRECT STATEMENTS Program statements that do not begin with a line number are considered direct statements and AlphaBASIC PLUS executes them immediately For example READY A 5 PRINT A 4 EU 9 The first direct statement A 5 stores 5 as the value of the variable A in memory The second PRINT A 4 adds 4 to the value of A and since this is a direct statement it prints out the answer 9 Each direct statement is compiled and executed when it is entered You can define variables and change variable values using direct statements Certain statements are meaningless as direct statements and so are not allowed for example RESUME GOSUB etc If you enter an illegal statement you see Illegal in immediate mode AlphaBASIC PLUS allows multi statement lines as direct statements Multi statement lines are lines which contain more than one statement the statements are separated by colons As you enter direct statements AlphaBASIC PLUS checks them to see they are in proper form If they are not you see an error message Continuation lines are not permitted 3 3CLEARING MEMORY F
72. cannot use variables defined by other functions If the parameters passed to the function by the function call are a different type than those defined in the formal parameter they are converted before being worked on If you pass fewer variables to the function than are defined the unused variables of the parameter list are assigned a 0 or null value If the number of parameters passed to the function is greater than the number of formal parameters defined in the function the program ends and displays an error message For example if your function definition is FN TEST a b and you call it with a statement like Var FN TEST x y z you get an error It is not a good idea to pass multi level MAPped statements to a function because there is no way to access the lower level variables within the MAP structure If you re define a function using the same function name twice after a DEF statement you get an error message Be sure you don t begin any array names or variable names with FN or they will be interpreted as a function call If the F switch is being used with the compiler function calls must begin with FN this is for compatibility with programs already containing variable names beginning with FN At run time a function definition is a non operative statement therefore you can place your definition anywhere you like within your program file and you don t have to use GOTOs to bypass the function definition
73. causes the cursor to be positioned on the X 1 column on the current line For instance TAB 5 causes 5 spaces to be printed and the following characters begin in column six When supplied with two arguments such as TAB R C however the TAB function performs special CRT operations If the value of R is positive the R C arguments are treated as row and column coordinates for positioning the cursor on the terminal screen The specified characters are then printed beginning in that position As in other functions the R and C arguments may be expressions Terminals are assumed to begin with row 1 top of screen and column 1 left end of each row If the value of R is 1 the function is interpreted as a special terminal command and the C argument then specifies the code of the screen function you wish to use The codes are transmitted to the terminal driver TDV file in DSKO 1 6 which does the actual interpretation and performs the special function for your terminal You may be able depending on the capabilities of your terminal to do such things as display in reverse video draw lines on the screen display special characters etc If you have a color terminal you may select colors by setting R to 2 for a foreground color and to 3 for a background color The colors are 0 Black 4 Red 1 White 5 Yellow 2 Blue 6 Green 3 Magenta 7 Cyan For information on using your terminal s display features from within a program see y
74. connect to a single variable let s call it EMPLOYEE INFO Here is a visual representation of this idea EMPLOYER INFO y y y y EMPL NAME SOC SEC NUM EMPL NUM PAY RATE Now when you refer to the variable EMPLOYEE INFO for instance if you say READ 1 EMPLOYEE INFO you access the other four variables so the total information about the employee is brought in from the data file You may have noticed none of the variable names in the above diagram have a after it which is AlphaBASIC PLUS s usual way of denoting string variables This is because you specify what type of variable it is when you MAP a variable AlphaBASIC PLUS knows EMPL NAME is a string and knows what maximum size it can be since you also specify that in setting up the variable You can form a variable structure like the one above using different types of variables also In the above example EMPL NAME should be a string variable but EMPL NUM might be a numeric variable The variables can also be different sizes You can refer to a single element of the group or to the group as a whole 14 2THE FORMAT OF MAP STATEMENTS Now you have an idea what mapped variables are like let us take a look at the statement that sets up mapped variables The MAP statement has the form MAPn variable dim type size value origin where n is a positive number defining the level of the MAP statement
75. currently have OPEN This could cause corruption on the disk If you try to KILL a file another program has OPEN you see an error message You may not erase a file existing in an account outside of the project you are logged into For example if you are logged into account 110 2 and the program you are running tries to KILL a file in account 200 1 you see a Protection violation error message If you try to delete a protected file you see a Protection violationerror message If you did not use a result variable in the KILL statement this error message terminates your program If you did specify a result variable a 0 is returned in it The result variablereturns 1 on a successful deletion There is also a KILL function see Chapter 11 AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 15 15 9 10LOOKUP The LOOKUP statement looks for a file on the disk and returns a value which tells you if the file is found and if so how many disk blocks it contains The format for the statement is LOOKUP switch filespec result variable As in the OPEN statement ilespec is any string expression which evaluates to a legal file description the default extension is DAT The file specification can be up to 48 characters in length result variable can be any legal floating point or binary or integer variable However a binary or integer cannot return all the possible values that a floating point variab
76. des 1 4 6 1 Trees 2 nou em ha ee s 14 12 Type code 22s ke eR E 3 VERS asia wae eae ae doe 11 6 Version numbers 25 11 6 WAIT PILE lt td ss 15 8 15 17 Word boundaries 14 12 WORD v eeck veseiehRIe OR eS 11 1 WRITE barata CREE aos 15 2 15 6 15 17 15 21 MATER da SEM e 15 2 15 22 WRITELN 3 elt dva Et pesetas 15 22 WRITTEN qu acosa 15 22 AGA a o a oe 9 31 18 2 XCALL loading 22 0084 ita re 18 2 KOM eves oad ated aga e 8 20899 AD qe 7 2 CJ 12 7 M idiomas es 12 4 O zero totus iere deat ecd te e omg 3 4 I M HOOP 12 8 AlphaBASIC PLUS User s Manual Rev 02
77. designating the initial and terminating values of the control variable as well as in the STEP expression 14 2 3 5Integer Data AlphaBASIC PLUS supports true integers of one two or four bytes The default size is 4 These integers are stored in binary form Integers offer increased speed of calculation over floating point variables 14 2 4Size The size parameter in the MAP statement is optional but if it is used it must be a decimal number specifying the number of bytes to be used in the variable If it is omitted it defaults to 0 for unformatted and string types 6 for floating point types 4 for integer types and 2 for binary types The size parameter of floating point variables MUST be 4 6 or 8 Integer variables must be 4 2 or 1 Binary variables must be 1 2 3 4 or 5 String and unformatted variables must be less than 65 535 bytes in size 14 2 5Value An initial value may be given to any mapped variable except an array variable by including any valid expression in the value parameter This value may be a numeric constant a string literal or constant or a complete expression including variables AlphaBASIC PLUS User s Manual Rev 02 Mapping Variables Page 14 7 Remember however the expression is resolved when the MAP statement is executed at run time and the current value of any variable within the value expression is the one used to calculate the assignment result You may reload the initial value by going back
78. duplicate line number errors O makes your object code file smaller and makes the program run faster but error messages don t show the line where the error occurred AlphaBASIC PLUS User s Manual Rev 03 Writing Program Files P option option PX number value R IS IX E AQ Page 5 5 Requests that the compiler and runtime systems select a particular option for processing An option can change the default operation of either or both COMPLP and RUNP Each option is assigned a number 1 through 64 See Appendix J for details A shorthand way to enter a large number of options Number is either 1 or 2 If number is 1 then value reflects settings for options 1 through 32 If number is 2 then value reflects the settings for options 33 through 64 See Appendix J for more details Specify as few options as possible The compiler will make reasonable efforts to spot unneeded options and inform you See Appendix J for details This switch can be used in two ways First to display features and available options of COMPLP To do this type COMPLP R Second this switch can incorporate the time and date of compilation together with COMPLP s version numbers inside the run file You can view the run file information by using RUNP s R switch To incorporate this information type COMPLP filename R Note this option will change the hash of the run file every time a compilation is done even if n
79. error code is zero 0 Operation aborted due to fatal error if error code is non zero 2 Operation aborted due to error or C 4 Operation completed with errors 6 Operation completed with warnings only The next three bits are reserved for future use The final ten bits identify the error ERROR CODE ERROR 0 No error detected 1 File specification error 2 Insufficient free memory 3 File not found 4 File already exists 5 Device not ready 6 Device full 7 Device error 8 Device in use 9 Illegal user code 10 Protection violation 11 Write protected 12 File type mismatch 13 Device does not exist 14 Illegal Block number 15 Buffer not INITed 16 File not open 17 File already open 18 Bitmap kaput 19 Device not mounted AlphaBASIC PLUS User s Manual Rev 02 Page G 2 ERROR CODE 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 Appendix G ERROR Invalid filename BADBLK SYS has a bad hash total BADBLK SYS is in unsupported format BADBLK SYS not found Insufficient queue blocks MFD is damaged First logical unit is not mounted Remote is not responding File in use Record in use Deadly embrace possible File cannot be deleted File cannot be renamed Record not locked Record not locked for output LOKSER queue is full Device is not file structure
80. evaluated in more than one way so a hierarchy of precedence is built into AlphaBASIC PLUS to determine which operations are done first For example NUMBER 1 4 6 makes NUMBER equal to 25 because multiplication has precedence over addition 4 6 is done before 1 is added If addition was higher in precedence then NUMBER would equal 30 1 4 would be done then 6 A waiting list For example when printing files a queue is used so the files sent to the printer do not print all at the same time but rather in an orderly way first come first served A method of storing data where the data is placed at random in memory and pointers keep track of where the data record is This type of data storage makes data retrieval faster A piece of data For instance if you think of a data file as a bookcase each record is like a book a separate unit of data contained within the file The process of transferring a file from user memory which is temporary to a disk which is permanent Storing variables by multiplying them by a power of ten so the decimal fraction isn t stored This is done so mathematical operations are more accurate Useful if you use large or long numbers which may cause round off errors A method of file storage in which each item of data follows the previous item of data in order Sequential data files are usually slower for data retrieval than random files but they can be edited usi
81. file commands or vice versa Check the file type and your OPEN statement for the file and correct the file IO statements for that channel number Initializer in SUBPROGRAM parameter ignored You specified an initializer value in a PARAMETER statement or in a MAP statement in a subprogram contained in a INCLUDE lt filename gt P statement Subprogram parameters cannot be initialized or have a default value assigned They will receive their values from the SUBCALL in the calling program AlphaBASIC PLUS User s Manual Rev 02 Page A 12 Appendix A Insufficient memory to load program name The RUNP program did not find enough free memory to be able to load the specified program See your System Operator about increasing your memory and or see Appendix C for hints on making your programs more memory efficient Integer expected Adjust your code so the expected condition is fulfilled Internal compiler error number number Contact Alpha Microsystems and report the problem and how it happened Internal PRAGMA error An internal compiler error was generated when processing the current statement Contact your dealer or Alpha Microsystem Technical Support and have the offending source file and statement ready Invalid filename Make sure the filename contained six or less characters and has a valid extension Invalid number or illegal format for P list COMPLP cannot understand your option selection list for a P of PX switch Invalid
82. if B is found within A The format is INSTR position expression expression Character position is measured from the start of the string with the first character position represented as one Here are some direct statements to illustrate AlphaBASIC PLUS User s Manual Rev 03 Functions Page 10 7 READY AS ELEPHANT RU BS ANT ETA PRINT INSTR 1 A B UN 6 PRINT INSTR 8 MEADOWLARK LARK 0 In the second example the specified string LARK is not found in the string ARK which is the substring starting at the 8th position therefore a zero is returned 10 3 5LCS A Returns a string which is similar to the argument string A but with all characters translated to lower case For example READY STRSIZ 20 Um A A is for Alpha tuy PRINT LCS A a is for alpha LCS is useful for checking input when the case is not certain For example IF LCS VARS yes THEN GOTO START is easier than using IF VARS YES OR VARS yes THEN GOTO START 10 3 6LEFT A X Returns the leftmost X characters of a string expression For example READY A Now is the time EUR PRINT LEFT AS 8 Now is t AlphaBASIC PLUS User s Manual Rev 03 Page 10 8 Chapter Ten 10 3 7LEN A Returns the number of characters in a string expression For example READY STRSIZ 50 RETURN AS Wherefore art thou Romeo RUN PRINT LEN AS 26 This is also
83. in detail in Chapter 13 9 43SIGNIFICANCE The format is SIGNIFICANCE value The significance statement lets you dynamically change the default value of the maximum number of digits to be printed for unformatted numbers value can be any number from 1 to 11 for AMOS variables and from 1 to 15 for IEEE variables Rounding off to the specific number of digits is not done until just before printing the result AlphaBASIC PLUS User s Manual Rev 02 Page 9 28 Chapter Nine value Can be a literal number or a variable and is truncated to an integer if expressed as a decimal unless IEEE variables are being used in which case it is rounded For example SIGNIFICANCE 3 6 is equal to SIGNIFICANCE 3 with AMOS variables or SIGNIFICANCE 4 for IEEE variables The statement SIGNIFICANCE 8 for instance sets the number of printable digits to 8 The current significance is ignored when PRINT USING is in effect Note the SIGNIFICANCE statement only affects the final printed result of all numeric calculations The calculations themselves and the storage of intermediate results are always performed in full precision to reduce the number of errors The significance default is 6 digits This is equivalent to standard single precision formats used in most of the popular versions of BASIC The significance is not reset by RUNP and therefore may be set in interactive mode in a d
84. in the statement String literals can include apostrophes NAMES Mortimer T Smith s Quotation marks can be included in the constant by writing two consecutive quotation marks READY QUOTES Then he said Hello there PRINT QUOTES Then he said Hello there AlphaBASIC PLUS User s Manual Rev 02 Variables Page 6 13 READY QUOTES Then he said Hello there PRINT QUOTES Then he said Hello there A string literal cannot be split over more than one line without using a runtime concatenation operator 6 2 5Default Data Type AMOS floating point format is the default format for all variables unless explicitly defined otherwise This can be achieved by eAppendinga to a variable name to specify it is a string variable eAppendinga gt to a variable name to specify it is a four byte integer variable eUsing a MAP statement to set the data type and size of the variable Note that if the MAP statement specifies the F data type without specifying its size the format and size of the variable will change depending on whether or not the program was compiled with the l switch Compiling with the l switch changes the default floating point format from AMOS to IEEE double precision eCompiling with the I switch changing the default type to IEEE double precision Note that numeric literals without a decimal point or exponent marker are always integer variables 6 3ARRAY VARIABLES
85. is displayed as the file specified in the INCLUDE command is copied into your program Deadly embrace possible Your program has opened files out of sequence with their order on the File Locking data base This message only appears if the deadlock check indicators are set in the File Locking data base DELETE what You specified DELETE without specifying what line s are to be deleted Device does not exist The device you specified in a file operation OPEN LOOKUP etc does not exist Make sure your entry was typed correctly Device error An error has occurred on the referenced device Check the documentation for that device to determine how to correct the error before rerunning the program Device full The specified device has run out of room during a PRINT CLOSE or ALLOCATE operation Remember an ALLOCATE requires contiguous disk space so this error may occur when there are still a number of non contiguous blocks available Device in use The specified device is currently assigned to another user Wait until that user is finished before running your program Device is not file structured The device you were trying to access is not an accessible device Check your specification for spelling or talk to your System Operator to find out what devices are accessible on your system AlphaBASIC PLUS User s Manual Rev 02 Page A 6 Appendix A Device not ready The specified disk is not ready for use Check your de
86. is also changed But in a user defined function you also have access to all the other variables and environment settings changing any of them will be reflected in the calling program Just like subroutines user defined functions are part of the calling program s source code file and are compiled together into a single RP file Other programs cannot access that copy of the user defined function at run time Subprograms go a step further They support parameters and local variables But they do not allow the changing of calling program variables unless they are passed as parameters Neither are changes to the calling program s environment allowed with a few minor exceptions Any environment change will only be effective for the duration of the execution of the subprogram The runtime system remembers the calling program s environment before executing the subprogram and restores that saved copy after the subprogram returns to the calling program AlphaBASIC PLUS User s Manual Rev 02 Chaining and Subprograms Page 16 5 16 2 2Types of Subprograms Subprograms can exist in two forms The first is in the main program file in which case they are compiled together with the main program into one RP file and are not accessible outside that RP file There can be up to 50 subprograms in the main file but each one must come after the main program at the end of the file Such subprograms are termed internal subprograms The second form is in a comp
87. links to arrays 8 Size of variable storage area excluding arrays 9 Size of dummy data termination field always zero 10 Size of file I O linkage and buffer area 11 Size of variable array storage area dynamically allocated at run time 12 Size of the user partition left free for use 13 Size of area between top of heap and top of stack less required gap size 14 Size of string work area The statement PRINT MEM is equivalent to PRINT MEM 0 AlphaBASIC PLUS User s Manual Rev 04 Page 11 4 Chapter Eleven 11 5TIME Retrieves the time of day from the system monitor communications area You cannot set the system time from within AlphaBASIC The format is TIME modifier where modifier Is 1 Internal format 0 Same as AlphaBASIC internal format 1 Separated format If modifier is not specified or if it equals 0 the result is in internal format a two word integer representing the number of seconds since midnight See your Monitor Calls Manual for more on separated format Normally TIME is used to measure time intervals For example X TIME GOSUB SORT FILE Y TIME PRINT It took Y X seconds to sort the file You can use ODTIM see Chapter 10 if you want a formatted time display Here is an example of a program to display the time in separated format MAP1 The Time MAP2 Hours b 1 MAP2 Minutes b 1 MAP2 Seconds b 1 MAP2 Excess b 1 MAP1 Ti
88. location X and puts the word in A A LONG X Reads decimal memory location X and puts the longword in A 11 2DATE gf The DATE system function returns the system date in a two word format You cannot set the system DATE using this function The format is DATE X where x is 1 Internal format 0 Compatibility same as AlphaBASIC separated format default 1 Full year x 10000 month x 100 day For example 19950422 In separated format the year returned is actually year 1900 For example 1997 is returned as 97 2001 is returned as 101 See your Monitor Calls Manual for information on separated format DATE is mostly used for comparison purposes to see how many days have passed between events etc Use ODTIM see Chapter 10 if you want an understandable formatted date display Here is an example of a program to display the date in separated format MAP The Date MAP2 Year b 1 MAP2 Day of the Week b 1 MAP2 Month b 1 MAP2 Day b 1 MAP1 Date Format I1 4 The Date Date Format DATE 0 PRINT Day Day of the Week Month Year You can use a similar program to compare days days of the week months or years See Chapter 14 for using the symbol within MAP statements AlphaBASIC PLUS User s Manual Rev 04 System and File Functions Page 11 3 11 310 X E Allows the input output ports to be selectively read from or written to In both cases only one byt
89. modifier has two distinct formats beginning position ending position beginning position substring length The first format defines the substring in terms of its beginning and ending positions within the string and uses a comma to separate the two arguments The second format defines the substring in terms of its beginning position within the string and its length using a semicolon to separate the arguments AlphaBASIC PLUS User s Manual Rev 02 Page 8 2 Chapter Eight The beginning and ending positions are defined as character positions within the string relative to either the left or right end A positive value represents the character position relative to the left end of the string with character position 1 representing the first leftmost position A negative value represents the character position relative to the right end of the string with character position 1 representing the last rightmost position For example assume a string consists of the letters ABCDEF The positions are defined in terms of positions 1 through 6 left relative or positions 1 through 6 right relative A B C D E F 6 characters within main string 12 3 4 5 6 left relative position values boe orden pec right relative position values Allowing negative values for right relative positions lets you find characters in a string without having to calculate the total size of the string and work from the left The substring length a
90. not full If it isn t something went wrong when the compiler tried to create the output file on the disk Report the problem and the circumstances to your System Operator or your Alpha Microsystems representative for help File already exists Your program tried to create a file which already exists You may not need the section of code that creates the file or you may need to install a check using LOOKUP to determine if the file exists before you try to create it File already open You have attempted to open a file on a channel number that is in use You may not need that OPEN statement or use a different channel number File cannot be DELETEd Your program tried to delete a file that has File Locking DELETE protection If you really do want to delete the file change its status under File Locking first File cannot be RENAMEd Your program tried to rename a file that has File Locking RENAME protection If you really do want to rename the file change its status under File Locking first File has been opened exclusively A file that COMPLP wants to process or RUNP wishes to execute has been opened exclusively by another job on the system Wait and try again later File in use The file your program wants to access is already locked by another user You may want to use the WAIT FILE option with the file access statement File Locking queue is full Your program attempted to lock a record or file and there was no room in
91. of string data INPUT LINE loads into the specified string variable an entire line of data up to but not including the first LINE FEED character it encounters lt removes a Carriage Return character if one immediately proceeds the LINE FEED character but not if it is embedded in the line Therefore DO NOT specify more than one string variable in an INPUT LINE statement If you use INPUT or INPUT LINE to read data into a variable that contains a null character that variable is terminated by that null character even if other data follows it The only case where this is not true is with unformatted variables AlphaBASIC PLUS never prints a question mark prompt for INPUT LINE as it does for INPUT but you may include your own prompt string which AlphaBASIC PLUS displays as a request for data It must be a string literal enclosed in quotation marks Unlike INPUT if you press in response to a data request INPUT LINE sets the variable to zero if numeric variable or null if string variable Remember in a like case INPUT leaves the value of the variable unchanged AlphaBASIC PLUS User s Manual Rev 02 Page 9 18 Chapter Nine When you use INPUT LINE remember the default size of unmapped string variables is ten characters if you want to use larger strings use the STRSIZ statement to reset the default string size or use a MAP statement for the string variable specifying the size you need See below for information on STRSIZ Some
92. or until you exit interactive mode AlphaBASIC PLUS User s Manual Rev 02 Interactive Mode Page 3 7 3 7LISTING A PROGRAM LIST If you have a program in memory you can display it by entering LIST READY LIST UN 10 INPUT Enter a number NUM 20 PRINT 30 PRINT NUM 40 INPUT Enter a second number NUM2 50 PRINT 60 PRINT NUM NUM2 NUM NUM2 If the program is longer than fits on your screen use the NO SCRL key or press e J C and m o to stop and resume the display or press c8 J C c to interrupt the listing If you only want to see part of your list you can ask for a section by adding the beginning and ending line numbers to the LIST command For example READY LIST 30 50 QEN 30 PRINT NUM 40 INPUT Enter a second number NUM2 50 PRINT Or if you want to see a single line READY LIST 60 FEWN 60 PRINT NUM NUM2 NUM NUM2 You may use a blank space or a hyphen in the LIST command where a comma is used for example LIST 30 500r LIST 30 50 3 8COMPILING A PROGRAM Each statement you enter is checked when you press A If the statement is correct nothing happens If there is an error in the statement you see an error message When you run a program explained below AlphaBASIC PLUS automatically compiles the program if it is not currently compiled You can also use the COMPILE command to compile the program For example READY COMPILE E
93. part of your program For example INCLUDE INVEN BPI You may use INCLUDE in interactive mode but it cannot be a direct statement Included files can be nested up to 16 deep You can specify these options with INCLUDE E ext Changes the file extension that COMPLP uses as a default for INCLUDE processing from BSI to ext for this INCLUDE only P MAP1 statements are changed to PARAMETERS if the included file is to be used as a subprogram Lets the same module be included either as program code or subprogram S n Default search path If n 0 the default searches only your PPN If n 1 searches your PPN and P 0 account If n 2 searches PPN P 0 and BP The P switch lets you use the same file in both programs and subprograms For example if you had a file called LABEL BPI that contained MAP1 Label MAP2 Name MAP2 Street address MAP2 City state zip You could include it in a BP file using INCLUDE LABEL BPI If you wanted to include it in a subprogram file however normally it would not compile because subprograms use PARAMETER statements instead of MAP1 statements By specifying INCLUDE LABEL BPI P In your subprogram file the MAP1 statements would be compiled as PARAMETER statements thus allowing them to work within the subprogram this does not change the LABEL BPI file There should be no spaces before the switches in an INCLUDE l
94. pause These pauses combined with the single step feature can help you locate errors in your programs AlphaBASIC PLUS User s Manual Rev 02 Page 3 2 Chapter Three There are also a few disadvantages to interactive mode Because you are sharing memory with the AlphaBASIC PLUS interpreter program your programs cannot be as large as if they were created with AlphaVUE we ll discuss that method of writing programs in Chapter 5 eYou must use line numbers making it more difficult to read and modify your program Having line numbers restricts your program to a maximum size of 65 535 lines elt is more difficult to edit your program because you must retype an entire line to change something Therefore you will probably use interactive mode if eYou are new to AlphaBASIC PLUS and want to try out BASIC statements or small programs eYour program is in the early stage of its development and you want to use the debugging features eYou want to use direct statements to do mathematical calculations or test short processes To use interactive mode first make sure you are at monitor level where you see the AMOS prompt symbol If you do not see a prompt press c amp J Cc If the prompt still does not appear see your System Operator When you see the prompt enter BASICP EUN You then see AlphaBASIC PLUS Version X X XXX READY READY is the AlphaBASIC PLUS prompt symbol You are now in interactive mode You
95. process problems of conflicting and incompatible TCRT functions are avoided Calls marked with an asterisk are either obsolete calls or calls for special purposes We recommend they not be used as they may change in the future TCRT CODE FUNCTION 0 Clear Screen and set normal intensity 1 Cursor Home move to 1 1 2 Cursor Return move to column 1 without linefeed 3 Cursor Up one row 4 Cursor Down one row 5 Cursor Left one column 6 Cursor Right one column 7 Lock Keyboard 8 Unlock Keyboard 9 Erase to End of Line 10 Erase to End of Screen 11 Enter Background Display Mode reduced intensity 12 Enter Foreground Display Mode normal intensity 13 Enable Protected Fields 14 Disable Protected Fields 15 Delete Line 16 Insert Line 17 Delete Character 18 Insert Character 19 Read Cursor Address 20 Read Character at Current Cursor Address 21 Start Blinking Field AlphaBASIC PLUS User s Manual Rev 02 Page D 2 TCRT CODE 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Appendix D FUNCTION End Blinking Field Start Line Drawing Mode enable alternate character set End Line Drawing Mode disable alternate character set Set Horizontal Position Set Vertical Position Set Terminal Attributes Cursor on Cursor off Start Underscore End Underscore Start Reverse Video End Reverse Video Start Reverse Blink End Reverse Blink Turn Off S
96. representation and back again Some decimal fractions cannot be exactly expressed as a floating point fraction in a finite number of digits and so a round off error occurs The error is only visible because our program set the number of significant digits to 11 the usual number of significant digits is six Such errors can accumulate and present themselves when you do a large number of multiplications and divisions using decimal fractions AlphaBASIC PLUS has a scaling feature which helps this problem by storing all floating point numbers with a scale offset This offset tells AlphaBASIC PLUS where the 11 absolute accuracy digits are located in relation to the decimal point AlphaBASIC PLUS does this by multiplying every input number by the scaling factor and then dividing it out again before printing AlphaBASIC PLUS User s Manual Rev 02 Page 13 2 Chapter Thirteen This is a simplified explanation and many other checks and conversions are done internally to scaled numbers If you are interested in more detail on scaling numbers see the section at the end of this chapter 13 1THE SCALE STATEMENT Scaled arithmetic is normally entered at the start of a program and continues in effect throughout the program The statement for setting the program into scaled mode is SCALE factor factor must be an integer digit in the range of 35 to 35 It may not be a variable since scaling is done at compile time for constant values as well as a
97. switches one for each constant The definitions are stored in an internal buffer for processing before the first line of the source file is read and are processed sequentially in the order they are defined on the command line The size of the buffer is approximately 200 bytes Creates an RPD file for use with the AlphaBASIC PLUS debugger see Chapter 22 Specifies number default is 100 of errors to allow before aborting compile Normally user defined functions begin with FN and variables may not begin with FN This switch changes this so functions must begin with FN If you convert a program with many variables that begin with FN to AlphaBASIC PLUS this lets those variables remain as they are without generating an error Allows you to compile a program which does a GOTO or GOSUB into a loop structure You will receive a warning message but the compile will complete Selects IEEE format for floating point numbers as the default See Chapter Six for more information on IEEE COMPLP prints a message after processing every 1 000 lines of source file Causes an error message to be displayed when COMPLP finds an unmapped variable Helpful for verifying all variables are mapped See Chapter 14 for more on mapping variables Cancels the COMPLP statistical display You see appropriate error messages but none of the COMPLP statistics Removes line number references in your compiled object code file It still reports
98. the S mode in command files If T is specified the output of the command is displayed on the terminal as if T was used in a command file If no switch is used the result is in whatever mode the system is in If the AlphaBASIC PLUS program was called from a command file the output display will be what is set by the command file The ERR 3 function see Chapter 17 reports the error status code this can help you determine whether the AMOS command executed properly Here are some examples of the AMOS statement AlphaBASIC PLUS User s Manual Rev 02 Page 9 2 Chapter Nine E AMOS TIME AMOS T DIR W DSKO 1 4 LIT AMOS S User request Be sure ECHO is set see ECHO below before you use AMOS In some cases your job can hang if NOECHO is set and an AMOS command is executed When it starts up AlphaBASIC PLUS remembers and sets up some internal variables based on the system environment It does not re scan its environment after an AMOS statement Thus you can get unexpected or undesired results if you change the system environment e g your terminal driver out from under AlphaBASIC PLUS by using certain command strings without restoring the original environment before continuing 9 2CALL See GOSUB below 9 3CASE See SWITCH CASE below 9 4CHAIN The format is CHAIN filespec Where filespec is a string literal or a string variable filespec may have the forms devn RP filespec p pn ar
99. the DIM statement is executed The number of elements in the resulting array equals B times C If a reference to an array is made during program execution without a previous DIM statement to define the array AlphaBASIC PLUS assigns a default array size of 10 elements for each subscript level String arrays may be allocated such as DIM A 5 The size of the array depends on the current string size in effect as specified by the last STRSIZ command or the default of 10 seen by the compiler since each element in the array must be this number of bytes or less For instance if the current STRSIZ is 10 the statement DIM A 5 allocates 5 elements multiplied by 10 bytes per element or 50 bytes of memory for the array Here are some examples of valid DIM statements Jg IM A 10 DIM TEST A B 4 IM A B 4 IM C 8 8 C 10 4 iz Jg AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 5 You may not use the DIM statement within a user defined function For more information on arrays see Chapter 6 9 9DIVIDE BY 0 Turns off the Divide by zero error When this statement is executed all attempts to divide by zero result in an answer of 0 instead of an error NO DIVIDE BY O see below turns the error condition back on 9 10DO WHILE UNTIL LOOP Executes a series of statements while a condition is true or until a condition is met The format is DO WHILE and or UNTIL condition
100. use of any characters Since these characters are never printed but simply define the size of the field by which a string is to be formatted non blank characters serve only as a comment However when using several string fields within a single format string it can be useful to visually separate them from the spaces between the fields by using non blanks within the backslashes For example wy fieldl X field2 N field3 String fields allow you to define the placement and size of string data For example READY STRSIZ 20 EUR AS Now is the time RETA PRINT USING As he once said N V AS RETURN As he once said Now is the time If the string to be formatted is larger than the string field AlphaBASIC PLUS truncates the extra characters If the string to be formatted is smaller than the string field AlphaBASIC PLUS adds trailing blanks to the string to make it the same size as the field and thus left justifies it in the field You may combine string and numeric fields in a single format string For example READY STRSIZ 25 RETURN MAP1 MASK S 38 10char 15 char REUN C in millions EU PRINT USING MASK 1979 34 556 C 1980 678 456 C Emm 1979 34 56 in millions 1980 678 46 in millions Remember the default string size is 10 characters so explicitly define any strings over 10 characters by using MAP statements or by including a STRSI
101. using the ALLOCATE statement which gives the number of physical 512 byte blocks to allocate It is up to you to calculate the maximum number of logical records required in the file and then to calculate how many disk blocks are required to completely contain the number of logical records you desire For instance assume the logical record size is 100 and you need a maximum of 252 logical records in the file Each disk block is 512 bytes and therefore contains 5 logical records This number 5 is called the blocking factor because it is the number of records that fit into each block of disk space You need 252 logical records so dividing 252 by 5 gives 50 full disk blocks plus 2 logical records remaining Since the file must be allocated in whole disk blocks you need 51 blocks which gives you a maximum of 255 logical records These logical records are referred to in your program as records 0 through 254 since the first record of any random file is record 0 unless you have used FILEBASE See FILEBASE below When figuring out how many blocks you need use this formula BLOCKS RECORDS NEEDED INT 512 RECORD SIZE And round the result BLOCKS up to the next integer value RECORDS NEEDED is the number of records your program needs to handle and RECORD SIZE is the size in bytes of each individual record AlphaBASIC PLUS User s Manual Rev 02 Page 15 6 Chapter Fifteen E When
102. variable You can get this code using the ERF function See Error Processing below 19 3 7CREATE RECORD This statement creates a new record The format is CREATE RECORD file channel expression list The new key s are defined by the record content If a record with the same key exists and duplicate keys are not allowed the CREATE RECORD operation fails All indices are updated on a successful CREATE RECORD operation All errors trap The system DDB error code giving the reason for the error is in the error status variable You can get this error code using the ERF function See the section on Error Processing in this chapter 19 3 8DELETE RECORD The record last accessed successfully by a GET or FIND is deleted from the file Such a record must have been locked prior to a delete The format is DELETE RECORD file channel All of the indices are updated upon a successful delete All errors trap Starting in RUNP version 1 0 269 2 the default error reporting behavior of DELETE RECORD has changed significantly You can control this behavior using a compiler option See the description of compatibility option 1 in Appendix J for details This call is used to release the last record accessed or to release a specific record using its relative record number The format is RELEASE RECORD file channel record The optional parameter record specifies the relat
103. way of letting subprograms pass values back to the calling program Expressions cannot be passed by reference and default to call by value For example BCALL DEMO QA INT A Hn D NG SUBPROGRAM DEMO PARAMETER X F 6 AlphaBASIC PLUS User s Manual Rev 02 Page 2 CALL BY VALUE CHAINING COMPILE CONVERSION DEBUGGING DELIMITER DISK FILE Glossary The SUBCALL above references A rather than passing the value of A so A is used in place of X in the SUBPROGRAM formula The value of A is actually changed in the subprogram so PRINT A displays 5 A way of associating an ACTUAL PARAMETER with a FORMAL PARAMETER Functions use call by value to pass the value of a variable without affecting it For example Y 20 DEF FNA X X 1 PRINT FNA Y PRINT Y prints 21 then 20 The value of Y is passed to the function but the global value of Y is unchanged Moving from an AlphaBASIC PLUS program to another program or to a command file The process of changing an AlphaBASIC PLUS source file into an executable RUN file The process of changing one type of data into another For example if you have a string expression 45 you can convert it to a numeric value by using the VAL function The process of removing the errors or bugs from a program Most programs when first written do not work quite the way they are supposed to and so a period of debuggin
104. when you compile the program To force use of ISAM PLUS use ISAMP INDEXED or ISAMP INDEXED EXCLUSIVE 19 3 2GET GET LOCKED and GET READ ONLY The GET statement permits random access by key value This and other random access statements return status values and if the access is successful the associated relative record number GET LOCKED locks the record for update and has the same syntax as GET GET READ ONLY gets the record for a read only operation and the format is also the same as GET The format is GET channels WAIT RECORD ISAM KEY knum rel kval varlist where channel Channel number from the OPEN statement WAIT RECORD Wait until record is available knum The key specifier assigned when you created the file rel Search key relational operator between key and record gt etc kval Value of the key to search for varlist List of variables to store the record in The status values returned in the status variable defined in the OPEN statement are defined as ISAM NF 3 Key not found ISAM NA 2 Record not available locked ISAM LT 1 Found key with lesser value ISAM EQ 0 Found key with equal value ISAM GT 1 Found key with greater value If the key is found the relative record number variable is updated For example AlphaBASIC PLUS User s Manual Rev 03 Page 19 4 Chapter Nineteen GET 3 WAIT RECORD KEY 0 gt ABCD varlist gets the record whose prima
105. when RUNP initializes eThe Heap The Heap is formed at the bottom end of an AMOS memory module As RUNP does its work it often needs memory that s persistent for some time An example of this is the DDB and buffer required to access a file OPENed in AlphaBASIC Another example is the area needed to hold the RP file if it is not located in system or user memory When a particular memory requirement is no longer needed RUNP will return it back to the heap to be reused later The Heap acts as a pool or reservoir of free memory As more memory is used the Heap grows upwards in memory towards the C stack at the top of the memory module eThe C Stack The C stack grows downwards from the top end of the memory module that also holds the Heap The C Stack should not be confused with AlphaBASIC PLUS s Arithmetic Stack The Arithmetic Stack is in fact a persistent memory allocation made from the Heap The C stack is used by RUNP as it executes The C Stack grows downwards towards the Heap as RUNP internally calls its functions as it executes The requirement for the C stack is determined by the programmer who wrote RUNP and the complexity of your AlphaBASIC PLUS program There must always be a small amount of free space between the top of the Heap and the bottom of the C stack If the size of this area drops below a minimum the DELTA setting in the BPR file RUNP aborts with a non trappable runtime error AlphaBASIC PLUS User s Manual Rev 02
106. with the precision or accuracy of mathematical calculations or data format conversions Instead it controls the maximum number of digits to be output when printing numeric values The value to be printed is copied and the copy is rounded to the specific number of digits prior to printing The default value is six digits AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 8 WORKING WITH STRING VARIABLES This chapter discusses eWhat a substring modifier is eHow to use a substring modifier eGetting the size of the string work area 8 1WHAT IS A SUBSTRING MODIFIER Chapter 6 defined string variables These strings of characters can also be broken down into substrings A substring is a portion of an existing string and may be as small as a single character or as large as the entire string AlphaBASIC PLUS supports a unique method of manipulating substrings using substring modifiers Substring modifiers allow the substring to be defined in terms of character positions within the string relative to either the left or right end of the string The length of the substring is defined either in terms of its beginning and ending positions or in terms of its beginning position and its length You define a substring by using the string variable for example A followed by the substring modifier The substring modifier is two numeric arguments enclosed within square brackets for example A 1 3 8 2HOW DO YOU USE A SUBSTRING MODIFIER The substring
107. write operations as many times as desired The statement format is ALLOCATE filespec number of blocks record size As in the OPEN statement filespec is any string expression which evaluates to a legal file description number of blocks is a floating point expression which represents the number of physical 512 byte disk blocks to be allocated to the file truncated for AMOS variables or rounded for IEEE variables The optional record size sets the record size in the file directory entry of extended format disks This lets you have records of any size you wish If the file has a record size it must be opened with that same record size whenever it is accessed A record size of 0 is the default and means standard record size the same as not specifying record size For example ALLOCATE FILES BLOCKS ALLOCATE NEW DAT 20 50 Random files can also be created at command level using the command CREATE see the CREATE reference sheet in your System Commands Reference Manual AlphaBASIC PLUS User s Manual Rev 02 Page 15 10 Chapter Fifteen 15 9 2CLOSE The CLOSE statement ends the transfer of data to or from a file Once a file has been closed no further references are allowed to it until another OPEN statement for it is executed Any files still open when the program exits are closed automatically Closing a file locked by AMOS unlocks it The format of the CLOSE statement is CLOSE file chann
108. you execute the program it is in If one program uses a FILEBASE command when referring to a file all other programs which refer to that file should also use a FILEBASE command with the same value to be able to access the same record with the same record number If you are accessing multiple files within the same program and these files have different bases be sure to specify the accurate FILEBASE prior to accessing each file 15 9 6INPUT Once a sequential file has been opened for input you may use a special form of the standard AlphaBASIC PLUS INPUT statement to read data from the file The INPUT statement uses a file channel number corresponding to the file channel assigned in the OPEN statement The variables in the list may be either numeric or string variables but should follow the format of the data in the file being read You can INPUT numeric data into string variables but an attempt to INPUT a string variable into a numeric variable sets it to 0 The format is INPUT file channel varl var2 varN AlphaBASIC PLUS User s Manual Rev 02 Page 15 12 Chapter Fifteen When input data is read into the variable list all leading spaces are bypassed unless they are enclosed in quotes as in the non file form of the INPUT statement discussed in Chapter 9 Also all carriage returns and linefeeds are bypassed allowing the file created by any PRINT statements to contain formatted line data if desired Commas spaces and end o
109. 1 1 2 Label Names invicto rrr ns we Coreg wok ee ae 6 3 6 1 1 3 User Defined Function Names 6 3 6 1 2 External Assembly Language Subroutine XCALL Names 6 3 6 1 3 Subprogram NaMesS oooccoccccoo 6 3 6 2 VARIABLE YPES 000 igecade Pest ba rar dt e dt ee 6 4 6 2 1 Numeric Variables 02230 es IESU 6 4 6 2 1 1 integers cis REDE eR tees 6 4 6 2 1 04 True Integers viuo eor es 6 5 6 2 1 1 2 Binary Variables 6 5 6 2 1 1 3 Other Integer Representations 6 5 6 2 1 2 Heal Numbers socorro 6 6 6 2 1 2 1 AMOS Floating Point Numbers 6 6 6 2 1 2 2 IEEE Floating Point Numbers 6 6 6 2 1 3 Real Number Characteristics 6 7 6 2 1 4 Real Number Mathematics 6 7 6 22 Sing Variables duce rbv a o bel 6 9 6 2 3 Unformatted Variables 0 000 6 10 6 2 4 Literals and Constants 0000 cece eee 6 10 6 2 4 1 Integer Literals and Character Constants 6 10 6 2 4 2 Alterative Radix Constants 0005 6 11 6 2 4 3 Floating Point Literals vemoss Ro 6 12 6 2 4 4 String Literals ore RR em em 6 12 6 2 5 Default Data Type i e sed ERE RE denen s 6 13 AlphaBASIC PLUS User s Manual Rev 04 Table of Contents Page iii 6 3 ARRAY VARIABLES i4 iss ds 6 13 CHAPTER 7 EXPRESSIONS AND EVALUATION 7 1 WHAT IS AN EXPRESSION 0 azi then Aiea th anges 7 1 7 2 MATHEMATICAL EXPRESSIONS 0 00000
110. 146 102 66 Latin Small Letter F LI g 147 103 67 Latin Small Letter G LI h 150 104 68 Latin Small Letter H LI i 151 105 69 Latin Small Letter LI j 152 106 6A Latin Small Letter J LI k 153 107 6B Latin Small Letter K LI 154 108 6C Latin Small Letter L LI m 155 109 6D Latin Small Letter M LI n 156 110 6E Latin Small Letter N LI o 157 111 6F Latin Small Letter O LI p 160 112 70 Latin Small Letter P LI q 161 113 71 Latin Small Letter Q LI r 162 114 72 Latin Small Letter R LI S 163 115 73 Latin Small Letter S LI t 164 116 74 Latin Small Letter T LI u 165 117 75 Latin Small Letter U LI V 166 118 76 Latin Small Letter V LI w 167 119 77 Latin Small Letter W LI X 170 120 78 Latin Small Letter X LI y 171 121 79 Latin Small Letter Y LI Z 172 122 7A Latin Small Letter Z LI 173 123 7B Left Curly Bracket Opening Curly Bracket Ps 1 174 124 7C Vertical Line Vertical Bar So 1 175 125 7D Right Curly Bracket Closing Curly Bracket Pe 1 176 126 7E Tilde So 1 DEL 177 127 7F Delete Cc AlphaBASIC PLUS User s Manual Rev 02 Character Sets Char acter PAD HOP BPH NBH IND NEL SSA ESA HTS HTJ CSI ST OSC PM APC NBSP wO w 4nrie Also Octal Called Value 200 201 202 203 204 205 206 207 210 211 212 213 214 215 216 217 220 221 222 223 224 225 226 227 230 231 232 233 234 235 236 237 240 241 242 243 244 245 246 247 250 251 252 253 254
111. 255 256 257 260 Decimal Value 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 Hex Value ISO IEC 10646 1 1993 E and Unicode 2 0 Name No Break Space Inverted Exclamation Mark Cent Sign Pound Sign Currency Sign Yen Sign Broken Bar Section Sign Diaeresis Copyright Sign Feminine Ordinal Indicator Left Pointing Double Angle Quotation Mark Not Sign Soft Hyphen Registered Sign Macron Degree Sign AlphaBASIC PLUS User s Manual Rev 02 Page F 5 Also Known As Type See Note Padding Character Cc High Octet Preset Cc Break Permitted Here Cc No Break Here Cc Index Cc Next Line Cc Start of Selected Area Cc End of Selected Area Cc Character Tabulation Set Cc Character Tabulation with Cc Justification Line Tabulation Set Cc Partial Line Forward Cc Partial Line Backward Cc Reverse Line Feed Cc Single Shift Two Cc Single Shift Three Cc Device Control String Cc Private Use One Cc Private Use Two Cc Set Transmit State Cc Cancel Character Cc Message Waiting Cc Start of Guarded Area Cc End of Guarded Area Cc Start of String Cc Single Graphic Character Cc Introducer Single Character Cc Introducer Control Sequence Cc Introducer String Terminator Cc Operating System Cc Command Privacy Message Cc Appl
112. 4 F rmmat ues reste sx ere eh 13 1 FMGD pt em up ea e Is 7 2 POR Irt fee 9 7 Formal parameter o 16 8 Formal parameter list 20 1 Format of argument lists E 2 Formatted output o o o o o o o 12 1 Formatted time date 10 13 Formatting characters 12 3 Formatting examples 12 8 Formatting symbols qc sted EF A 12 5 OES O La ea 12 3 Bite dati AA 12 6 Da DTE 12 7 O 12 7 Ad RA o ld ace 12 7 Ns A esp b ERREUR 12 5 VA PU ari adeat tT e SURE eee 12 7 cer 12 4 Pee o davit Satis due teta iu ied nud 12 8 Page Index 8 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index Page Index 9 FREQ asociada 11 3 Free memory usage o ooooo oo E 4 FUNCTION lt span es 22 7 FUNCUONS EN 10 1 NUME tt e xut Me oe 10 1 Trigonometric celso cem 10 4 GEL arta ue o es 19 3 GETEOGKED 5 od Mon ed vs 19 3 GETNEXT acia 19 4 GET NEXTLOCKED 19 4 GET NEXT READ ONLY 19 4 GEV PREV vob adas 19 4 GET PREV LOCKED ib Reus 19 4 GETPREVREAD ONLY sees ea ee 19 4 GETREADONLY ees eee ates 19 3 GETDKEY US y sa de Do PORE os 10 12 Getting a record by key 19 3 Getting key input 10 12 Getting next previous record 19 4 Getting statistical information 19 8 Going to another p
113. 5 The AlphaBASIC PLUS Library account DSKO 7 35 By your account we mean the account you are currently logged into If you specify a device AlphaBASIC PLUS does not search in memory but proceeds directly to that device using steps 3 and 4 AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 3 INTERACTIVE MODE This chapter discusses the AlphaBASIC PLUS interactive mode The topics are eWhat is Interactive Mode eClearing memory for a new program eCreating a program eSaving a program eCompiling a program Running a program eDirect statements 3 1WHAT IS INTERACTIVE MODE We call it interactive mode because you interact directly with the AlphaBASIC PLUS interpreter as you write or edit your program As you enter each line and press fe AlphaBASIC PLUS looks at the line and determines if it has been entered correctly whether what you enter is a legal AlphaBASIC PLUS statement Interactive mode is like being inside BASIC and gives you a number of advantages eSince AlphaBASIC PLUS checks each line as you enter it it can help you learn how to use the AlphaBASIC PLUS programming statements eYou can easily change lines or variables between program runs making testing various parts of your program or variable ranges and values simple einteractive mode allows you to run your program one line at a time This is called the single step feature eYou can also set breakpoints places inside your program which cause the run to
114. 6 12 2 6 Putting a Comma Every Three Digits 12 7 12 2 7 Fill Leading Blanks with Asterisks 12 7 12 2 8 Fill Leading Blanks with Zeros Z o ooooooo 12 7 12 2 9 Add a Trailing Minus Sign to a Number 12 7 12 2 10 Printing Numbers as Exponents 12 8 FORMATTING EXAMPLES AND HINTS ooo 12 8 TAB FUNCTIONS ra e ed Gees teed Kee eae da 12 9 AlphaBASIC PLUS User s Manual Rev 04 Page vi Table of Contents PART FOUR ADVANCED PROGRAMMING CHAPTER 13 SCALED ARITHMETIC 13 1 THE SCALE STATEMENT 00 as a dad 13 2 13 2 HOW THE SCALING FACTOR WORKS 00 0 0000 ee 13 3 CHAPTER 14 MAPPING VARIABLES 14 1 WHAT IS VARIABLE MAPPING 000020 o 14 1 14 2 THE FORMAT OF MAP STATEMENTS esses 14 2 14 2 1 MAP Level curie e RR RE da 14 3 14 2 2 Variable Names in MAP Statements 14 4 T423 TVPG c e 2 da ROPA eR id 14 5 14 2 3 1 Unformatted Data oooooooomooo 14 5 14 2 3 2 String Data weesoda te ROSE ET MER Sd 14 5 14 2 3 3 Floating Point Data oso mixes 14 6 142 344 Biridry Data dati cux ee a Mb dde 14 6 14 2 3 5 Integer Data sock eLRI e ERERRID IEEE RU 14 6 T4 2 rs A e a ose oues caus Eduensi di ird dee 14 6 rs MAU os raris eat ate te pte dust ard he as ad wr egt tie ok 14 6 142 B OIN s Loo teo utt Xetra m od eh Keno a tef 14 7 14 3 USING MAP STAT
115. 9 6 For languages using Arabic 8859 7 For modern Greek 8859 8 For Hebrew 8859 9 Known as Latin 5 The same as 8859 1 except for Turkish instead of Icelandic characters 8859 10 Known as Latin 6 for Lappish Nordic and Eskimo languages ISO 8859 1 also known as ISO Latin 1 has the required characters to display most Western European languages It supports Afrikaans Basque Catalan Danish Dutch English Faeroese Finnish French Galician German Icelandic Irish Italian Norwegian Portuguese Spanish and Swedish It cannot support Welsh due to two missing characters Latin Letter W with circumflex and Latin Letter Y with circumflex It is the preferred encoding for the Internet AMOS follows this lead and expects 8 bit aware software to use these ISO standards In passing the ISO 8859 1 standard is a subset of the Unicode 1 x and 2 0 standards which use 16 bit character sets to encode most of the world s alphabets Unicode has aligned itself with a further ISO standard for 32 bit character sets ISO 10646 1 1993 There are several mappings available such as UTF 8 which can map Unicode characters to a variable length 8 bit based encoding Also Octal Decimal Hex ISO IEC 10646 1 1993 E Also Known As Type See Called Value Value Value and Unicode 2 0 Name Note 0 0 0 Null Cc 1 1 1 Start of Heading Cc 2 2 2 Start of Text Cc 3 3 3 End of Text Cc 4 4 4 End of Transmission Cc 5 5 5 Enquiry Cc 6 6 6 Acknowledge Cc 7 7 7 Bell C
116. A ash 8 3 9 4 Subsinngs 25 22 a eene roges vr etes 8 1 to 8 2 10 6 ModifierS o o ooooo o 8 1 8 3 OVEMOW cre 8 2 Truncation oooo oooo ooo oo 8 2 14 5 SWITCH 2 lve aon ts oy Seah Pewee tea de 9 29 SV cov ars oes ete alae ee ead 11 1 Syntax errors scan shaw e RR RE 3 4 SYSUBAIB sit htawtateat fies REESE E 3 to E 4 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index System functions o ooooooooo 11 1 16 2 System memory ss 1 3 System subroutine library E 3 NEPA SG A A A MALE es 12 9 TAB functions zoe habe iim re ei ES 12 9 TAIN E ane ed a Rae 10 4 TORT codes ier ns doe 12 9 D 1 Terminal input tds e A oa 10 12 THEN iis e eo decer s eS 9 12 9 31 TIME 22 ab daa pic exh eiie 10 10 10 13 11 4 Timesharing pcs rre 1 3 Timing processes ooooooooooo 11 4 TO veer m 9 31 TRAGE dx etu tend eno aret ret 22 9 Trailing blanks arde 9 22 Trailing spaces ses acces ogee bee wae 10 10 Transferring to another program 9 2 Translation tables 10 13 TRAP sss aes awa oes oe oe ee 22 5 Trapping errors with Control C 17 4 Trigonometric functions 10 4 ACT 22 eben darned dundee eee 10 4 BSN US los bodied ide al 10 4 NIN X scenes cee eter aye ges 10 4 COSA tw a B CS 10 4 DATN X Y sig dada a cra 10 4 SING 2 Seale dos eg espe me v P e ees 10 4 TANI Eee usi Eua
117. AMOS command level If you are going to use subroutines keep this in mind and be sure to SAVE your program before running it To edit a program line you must re type the entire line as we did above You may use INCLUDE in interactive mode but not as a direct statement 3 5DELETING PROGRAM LINES DELETE The DELETE command is used to delete lines from the program text You can delete a line from the program by entering DELETE and the line number For example READY DELETE 40 You can also delete a group of line numbers by specifying a beginning and ending number For example to delete all lines between and including 40 and 150 READY DELETE 40 150 NJ Although you usually separate the two line numbers with a comma you can also use a dash space or some other non numeric characters The symbols 1 and are used by AlphaBASIC PLUS and won t be accepted Here is an example of a program listing before and after a DELETE AlphaBASIC PLUS User s Manual Rev 02 Interactive Mode Page 3 5 LIST REUN 10 FOR 1 1 TO 10 20 PRINT TAB I ONE 30 PRINT TAB I TWO 40 PRINT TAB I SIX 50 PRINT TAB I TEN 60 NEXT I READY DELETE 20 40 READY LIST ETA 10 FOR I 1 TO 10 50 PRINT TAB I TEN 60 NEXT I READY 3 6SAVING A PROGRAM SAVE Once you have your program entered or even when it is partially entered y
118. AlphaBASIC PLUS User s Manual RIGHT FROM THE START DSM 00045 04 O 1997 Alpha Microsystems REVISIONS INCORPORATED REVISION DATE 00 September 1989 01 April 1991 02 September 1996 03 May 1997 04 December 1997 AlphaBASIC PLUS User s Manual To re order this document request part number DSO 00045 00 This document applies to AMOS 2 3A PR 12 97 and later The information contained in this manual is believed to be accurate and reliable However no responsibility for the accuracy completeness or use of this information is assumed by Alpha Microsystems This document may contain references to products covered under U S Patent Number 4 530 048 The following are registered trademarks of Alpha Microsystems Santa Ana CA 92799 AMIGOS AMOS Alpha Micro AlphaACCOUNTING AlphaBASIC AlphaCALC AlphaCOBOL AlphaDDE AlphaFORTRAN 77 AlphaLAN AlphaLEDGER AlphaMAIL AlphaMATE AlphaNET AlphaPASCAL AlphaRJE AlphaWRITE CASELODE OmniBASIC VER A TEL VIDEOTRAX The following are trademarks of Alpha Microsystems Santa Ana CA 92799 AlphaBASIC PLUS AlphaVUE AM PC AMTEC AlphaDDE AlphaCONNECT DART inSight am inFront am ESP MULTI All other copyrights and trademarks are the property of their respective holders ALPHA MICROSYSTEMS 2722 S Fairview St P O Box 25059 Santa Ana CA 92799 TABLE OF CONTENTS PART ONE INTRODUCTION CHAPTER 1 INTRODUCTION 1 1 WHO IS THIS MANUAL WRITTEN FOR 2 0000005 1 1 1 2 WHA
119. AlphaBASIC PLUS simply prints it as part of the formatted data As another example READY PRINT USING 23 45 56 78 99 84 REUN 23 574 100 In the example above the symbol is NOT a special formatting character Another example READY PRINT USING Telephone 714 555 1212 EUN Telephone 714 555 1212 AlphaBASIC PLUS User s Manual Rev 02 Formatting Output Page 12 7 12 2 6Putting a Comma Every Three Digits Include a comma to the left of the decimal point in your format string to tell AlphaBASIC PLUS to put a comma every three digits to the left of the decimal point The comma defines one character position For example READY PRINT 6507501 89 USING 4 CEU 6 507 501 89 12 2 7Fill Leading Blanks with Asterisks Include two asterisks at the front of your format string to tell AlphaBASIC PLUS to replace any leading blanks normally output in front of a number with asterisks This is especially useful when printing checks defines two digit positions For example READY PRINT 231 69 USING H H HHHHH HH Cer kkk 221 69 You may want to use asterisk fill formatting when printing dollar amounts remember you may include a in the format string For example READY PRINT 231 69 USING S S1HHHHHHHHHHE IHE ED X kk 523 69 12 2 8Fill Leading Blanks with Zeros Z To generate leading zeros include the Z symbol within your format stri
120. C PLUS User s Manual Rev 04 Table of Contents Page vii 19 9 8 INPUT RAW nidad 15 14 O A naas u Ea a E A 15 14 159 10 LOOKUP cose ss 15 15 189 1H OPEN osas BEI a d e ue el 15 16 15 9 11 1 OPEN Modes cz S A ea gat 15 18 15 912 PRINT Sc a i iba ereat bm Ron ER RR 15 19 15 9 48 ERD EA utt es itd xen AA ERRE 15 19 15 9 T4 READE e e ene A RR d Re ete tene td a 15 20 15 9 15 MBAD HEAD ONLY 4 O de tra eub e aa EN 15 20 19 9 16 UNLOKR cuim Ae Rec UAE S e A a 8 15 21 19 9 i WAITE 09000 A Edo ode ia feng dot ri e ovi STERN Fac iso 15 21 15 9148 WRITE 005505 RS 15 22 19 9 9 WRITEN O in E AR eO EE 6 15 22 19 9 20 WRITELN a nd inte anal anne da eR opted eee teda d 15 22 CHAPTER 16 CHAINING AND SUBPROGRAMS 16 1 THE CHAIN STATEMENT 2 itas c dte turmis 16 1 16 1 1 Chaining to another AlphaBASIC PLUS Program 16 1 16 1 2 Chaining to System Functions 0000 eee 16 2 16 2 WHAT IS A SUBPROGRAM outra oh Rei Gee S 16 3 16 2 1 Subroutines User Defined Functions and Subprograms 16 4 16 2 2 Types of Subprograms 0 000 eee eee 16 5 16 2 2 1 Considerations for Internal Subprograms 16 5 16 2 3 Subprogram Structure 0 00 room 16 5 16 2 4 Subprogram Components 000 eee eee eee 16 6 16 2 4 1 Subprogram Name 0 00 eee eee 16 7 16 2 4 2 Parameters 2646 cence cee Rm RE 16 7 16 2 4 3 Subprogram Code 00 eee eee 16 9 16 244 SUBEND v eaen nivrh heu e
121. CMA standardized ECMA 94 which dealt with almost all European languages ECMA 94 was taken up by ISO as ISO 8859 1 through 8859 4 and standardized in 1987 Microsoft released MS DOS 3 3 in 1987 which used Code Page 850 This code page uses all the characters from ISO 8859 1 plus a few extra at code points representing the non printing characters A second code page Code Page 819 is fully ISO 8859 1 compliant F 1 1 The ISO 8859 Family of Standards and AMOS The ISO 8859 x character sets are designed for maximum interoperability and portability All of them are a superset of US ASCII and will render English text properly The code points OxAO through OxFF are used to represent national characters while the characters in the range 0x20 through 0x7F are the same as in the ISO 646 US ASCII character set Thus ASCII text is a subset of all ISO 8859 character sets and will be rendered properly by them The code points 0x80 through Ox9F are earmarked as extended control characters and are not used for encoding characters The ISO 8859 family of standards consists of AlphaBASIC PLUS User s Manual Rev 02 Page F 2 Appendix F 8859 1 For Europe Latin America the Caribbean Canada and Africa 8859 2 For Eastern Europe 8859 3 For SE Europe and a miscellany of alphabets such as Esperanto and Maltese 8859 4 For Scandinavia and the Baltic states mostly covered by 8859 1 also 8859 5 For languages using the Cyrillic alphabet 885
122. E E ET 10 4 TRUNCATION ops rh gen x htt iem en 10 3 Turning off keyboard echo 9 19 Turning on the keyboard 9 6 Type codes ic series E 1 Type independence 7 4 UGSA caca eed cem te ds s 10 10 Underscore cachito dni tard a 6 1 Unformatted variables 14 5 UNIFY erary Eois sce eas trn e nh 21 1 Unlocking All records cecus Bh0005SS ie e 19 7 lOS rese cen A Ee 15 21 Last accessed record 19 6 to 19 7 Recordi 143 ties XQ See Riv Rt 19 6 Record by number 19 6 UNEORB de ias er ata 15 21 19 7 UNTRAGE aviar 22 9 UNTRAR ce csi o ETHER ed 22 5 UPDATE RECORD ikeeike das nds 19 5 Updating a record soos 19 5 AlphaBASIC PLUS User s Manual Rev 02 Page Index 17 AlphaBASIC PLUS User s Guide Index Page Index 18 Use of free memory o ooo oo o E 4 User definable functions 20 1 Examples vatios eeeie 20 5 User impure area o oooomooo E 2 User memory partition 1 3 USING cocos Rr ER UESTRE REGES 7 2 9 81 12 1 Using command files from BASIC 16 2 Using defined functions 20 4 Using subprograms lesse 16 10 VALAS ani ood das cess bora E 8 2 aca atte E 7 7 10 4 Valle ion ou titi Sed ae eee 9 18 VARIABLE 4n e Us 22 9 Varlables 22x exe iaa 6 1 7 4 Length nera a aio o ale llas 1 4 Mapping seu ra ES te ee edad 14 1 Names bres c eet peto
123. EMENTS RR Rm a ees 14 9 14 341 ExampleS 5 tor ba oci ves e poU WIE d esc nds 14 9 14 4 USING MAPPED DATA WITH DATA FILES esses 14 11 14 5 HOW VARIABLES ARE ALLOCATED IN MEMORY 14 12 14 6 LOCATING VARIABLES DURING DEBUGGING 14 13 14 5 1 Examples tie dete Em era Hh een n e bnt 14 14 CHAPTER 15 THE FILE INPUT OUTPUT SYSTEM 15 1 15 2 15 3 15 4 15 5 15 6 15 7 15 8 15 9 WHAT ISA DISK FILE oo cote tik nm REIR E ES E AS ABRE ES 15 1 HE CHANNELS S oi See ae EN ed ade ERA Pte ode S eee x 15 2 INPUT OUTPUT STATEMENTS iR ERI RR evade ied ds 15 2 SEQUENTIAL FILES 5 nsu onm ew eae Sha eee eate 15 3 RANDOM FILES 5 Lux ve ro SU ORI RUE he AUS 15 4 15 5 1 Logical Records oes Ee Fuer rre rond ERE ess 15 5 15 5 2 Figuring Out How Many Blocks Your File Needs 15 5 15 5 3 Accessing Random Files oo oooooooo 15 6 FILE LOCKING FOR SEQUENTIAL FILES 24 15 8 FILE LOCKING FOR RANDOM FILES 00000 eeu 15 8 FILE LOCKING FOR ISAM PLUS FILES 0 005 15 8 PIEE STATEMENTS 4 2v pee i To ter AE A La M Pte 15 9 15 9 d OG ATES cues Sessa amo Ee oue epos dE Os 15 9 159 2 CLOSE iic sober A Rees Cerda Clm e gees 15 10 1593 CLOSER sta mea sio ie alas ERES 15 10 15 9 4 EOF Dinos e bw RE DERE 15 10 15 9 5 FILEBAS s ns rra erecta 15 11 15 9 5 INPUT cortadas o sd Aree 15 11 EST INPUT LINE SES e ted omo d de 15 13 AlphaBASI
124. ENDIX J COMPILER AND RUNTIME OPTIONS J 1 RESOLVING THE DILEMMA 2 x ictericia J 1 J 2 OPTION SPECIFICATION Sari a Et E PAWE S TIED J 1 J 3 CHECKING AVAILABILITY OF OPTIONS ooo J 2 J 4 ALTERNATIVE METHOD OF OPTION SPECIFICATION J 2 J 5 EFFECTS OF USING OPTIONS lt 2 23024 n RR Rm RA eee bee J 4 J 6 DEFINED OPTIONS prie ninda naa DR o Bd J 5 GLOSSARY DOCUMENT HISTORY INDEX AlphaBASIC PLUS User s Manual Rev 04 CHAPTER 1 INTRODUCTION This chapter introduces you to AlphaBASIC PLUS and discusses some of the concepts we ll be using throughout the manual The topics are Who is this manual written for eWhat is BASIC eHow is AlphaBASIC PLUS special eWhat can AlphaBASIC PLUS do eThe programs that make up the AlphaBASIC PLUS system What does an AlphaBASIC PLUS program look like eGraphic conventions we ll be using 1 1WHO IS THIS MANUAL WRITTEN FOR E This is a reference manual for the AlphaBASIC PLUS language It is not meant to be a tutorial for the BASIC language or to teach concepts of programming However we have tried to make this manual easy to use and understand In general the text of this manual is written with the assumption you are inexperienced with BASIC A glossary is provided near the back of this manual It defines terms used in AlphaBASIC PLUS and other terms relating to this manual and to the Alpha Micro system If you are an experienced BASIC programmer you may want t
125. Examples Let us take a mapped variable group MAP1 ADDRESS MAP2 STREET S 20 MAP2 CITY S 20 MAP2 STATE S 20 MAP2 ZIP CODE S 9 With this group we can do a number of things We could print the whole group to the terminal screen PRINT ADDRESS or write it to a file with a simple statement WRITE 1 ADDRESS And we could sort the information in useful ways by sorting the CITY STATE or ZIP CODE variables Another use of MAP statements is to set up arrays The following two statements produce identical arrays AlphaBASIC PLUS User s Manual Rev 02 Page 14 10 Chapter Fourteen MAP1 ARRAY 10 F 6 DIM ARRAY 10 Both statements produce arrays containing ten floating point variables referred to as ARRAY 1 through ARRAY 10 The first statement however defines its placement in memory in relation to other mapped variables Similarly the statements MAP1 ARRAY 5 MAP2 AR VAR 20 F 6 produce the same two dimensional array as DIM ARRAY 5 20 As another example these statements DIM WIDTH 10 DIM HEIGHT 10 produce two arrays each with ten variables But these MAP1 AREA 10 MAP2 WIDTH F 6 MAP2 HEIGHT F 6 produce one array with twenty variables in it The variables are still referred to as WIDTH 1 through WIDTH 10 and HEIGHT 1 through HEIGHT 10 but their placement in memory is quite different The WIDTH vari
126. HelloriSu A ag Wp RO a os 11 1 A ee area aren eee O er 11 5 LOOKUP Mer east TTE 11 4 RENAME 1322157252925 24M rers 11 6 File input output statements 15 2 File locking iii oe n 15 8 ISAM PLUS files 15 8 Random files 2 rr aa 15 8 Sequential files 15 8 File specifications 5 11 File statements ooomooo 15 9 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index ALLOCATE 2c pda S ERES uewP PESE 15 9 CLOSE ex tiet quet resi d 15 10 OLOSEK 2 ion th eta RR MERC RS 15 10 FILEBASE oan edt edi RE 15 11 INDE es enetcs dre eoa us DEA 15 11 INPUT LINE 2n Sd x 64d dere REA be 15 13 RIEL a When Pde ae aoe age 15 14 LOOKUP emend eit ia ada 15 15 OPERIS nds o tae Rn BUM E 15 16 PRINT cs 15 19 READ 1000 Aste cimas DRESSER 15 19 UNLOKR tse rides 15 21 WRITE ios 15 21 File channel numbers 15 2 15 10 FILEBAS E 3 acute svn ER FE ES 15 11 FILEBLOCK lt lt iaa 10 12 FileSpeC z cori meh pube s 1 6 PUES ais c epu mE rta e tS oe 10 6 FIND 222 pitiriasis RR E 19 5 EIBID NEXT tiras ala 19 5 RINDI PREYS ia caos 19 5 Finding a numeric value of a string 10 4 Finding next previous key 19 5 Finding string length 10 8 Finding the free bytes in memory 11 3 EDU sE 10 3 FIXTRN cg Bas ected e E Mt It 10 13 Floating point variables 14 4 to 14 6 IAS A t a eet e T 14
127. IC PLUS rounds the number so it contains the right number of digits in the fractional part If the format string has more digits to the right of the decimal point than the specified number AlphaBASIC PLUS fills in the unused digit positions with zeros as in the case of the number 200 above If the format string specifies any digits before the decimal point AlphaBASIC PLUS prints at least one digit before the decimal point for each number even if it is zero AlphaBASIC PLUS User s Manual Rev 02 Page 12 6 Chapter Twelve 12 2 5Dollar Signs and Numeric Fields Two dollar signs at the front of a numeric field format string tell AlphaBASIC PLUS to put a dollar sign in front of the formatted number defines two digit positions one of which is taken up by the dollar sign itself For example READY PRINT USING SS 17500 66 100 345 2 fem 17500 66 100 00 345 20 Notice the difference between using and using the single non formatting character in the format string READY PRINT USING S 17500 66 100 345 2 RuN 17500 66 100 00 345 20 Because you use to format data representing money amounts you may want to use the floating comma symbol in combination with See the section below for information on this formatting character Remember you can include non formatting characters in a format string In the case above a single dollar sign is not a formatting character and so
128. INT UCS A M IS FOR MICRO This is useful for checking input when the case is not certain For example IF UCS VARS YES THEN GOTO START is easier than using IF VARS YES OR VARS yes THEN GOTO START AlphaBASIC PLUS User s Manual Rev 03 Functions Page 10 11 10 4MISCELLANEOUS FUNCTIONS 10 4 1CMDLIN Returns a string containing the rest of the AMOS command line after RUNP program name For example if you enter RUNP FIGURE This is a test UN when FIGURE BAS contains this statement AS CMDLIN A contains THIS IS A TEST CMDLIN translates all characters to upper case CMDLIN thus lets you pass data into a program when the program is executed 10 4 2DITOS X Returns the given date in separated format See ODTIM below and DATE in Chapter 11 for more on date displays The format is DITOS date in internal format DITOS will operate correctly for dates in the range March 1 1900 to December 31 2099 10 4 3DSTOI X Returns the given date in internal format See ODTIM below and DATE in Chapter 11 for more on date displays The format is DSTOI date in separated format DSTOI will operate correctly for dates in the range March 1 1900 to December 31 2099 10 4 4ERRMSG X Returns a string of the runtime error message corresponding to an error number returned by ERR 0 The format is ERRMSG message number where message number is the error me
129. ISAM PLUS The ISAM PLUS program is a tool for organizing and retrieving data The name ISAM stands for Indexed Sequential Access Method and refers to the manner in which the data is organized ISAM PLUS is an advanced version of ISAM Even though the word Sequential is part of the ISAM name and they are referred to as indexed sequential files the Access Method is sequential not the file ISAM files are RANDOM files AlphaBASIC PLUS can process indexed sequential files by linking to the ISAM PLUS assembly language package AlphaBASIC PLUS attempts to load ISAMP SYS if it does not find it in memory Therefore if it is not in memory there must be enough memory available in your partition to load it ISAM PLUS supports multiple index files by using AlphaBASIC PLUS User s Manual Rev 03 Page 19 2 Chapter Nineteen some elementary ISAM PLUS statements allowing the direct control of index file and data file items We strongly recommend you use the AlphaBASIC PLUS command statements designed for file and record locking ISAM PLUS files are particularily vulnerable to simultaneous update problems Proper file and record locking keeps your data intact helps clarify your code and enhances compatibility with other systems and future Alpha Micro software It is important when reading the following sections you be familiar with opening and using random data files If you are not see Chapter 15 first It is also a good idea to be
130. LUS rounds the number to the next integer rather than truncating it For example READY PRINT 2367 88 USING EUN 2368 If the numeric field is too small to contain the specified number for example if we specify 650456 56 with the format string AlphaBASIC PLUS prints the number in standard format preceded by a symbol indicating overflow For example READY PRINT 150450 USING GEA 2150450 If the field is larger than the number AlphaBASIC PLUS right justifies the number inserting leading blanks into the digit positions not needed For example READY PRINT USING 23 23 Note that other formatting characters discussed below for instance the and symbols also define digit positions as well as perform special formatting functions AlphaBASIC PLUS User s Manual Rev 02 Page 12 4 Chapter Twelve You can t format string data with a numeric field format string If you try AlphaBASIC PLUS prints the format string showing it was unable to format the data For example READY PRINT USING Hi there RUN TEE 12 2 2Formatting a String Field 1 You may specify fields for string data by using the backslash symbol 1 Two backslashes define a string field whose size equals the number of characters enclosed in the backslashes plus the backslashes themselves Although the usual practice is to enclose blanks in the string field for example AlphaBASIC PLUS permits the
131. LY Allows you to OPEN a file for read only operations Does not allow any write operations to the file If the file is already open for exclusive use you cannot OPEN it with READ ONLY If you have a file open for READ ONLY another program can open it exclusively and lock you out you lose your access to the file Alm Do not try to OPEN a sequential file for more than one type of operation at the same D time For example don t OPEN a file for input and then OPEN the same file for output This could cause data corruption AlphaBASIC PLUS User s Manual Rev 02 Page 15 18 Chapter Fifteen filespec may be as brief as the name of the file in which case it is assumed to have an extension of DAT and to reside in the disk account you are logged into Or it may be a complete file specification if you desire giving the explicit location of the file which may be in another account or even on another disk drive Some examples OPEN 1 DATFIL INPUT OPEN A C OUTPUT OPEN 3 DSK1 OFILE ASC 200 20 OUTPUT OPEN 1 ACCTS VENDOR DAT RANDOM 100 RECNUM WAIT FILE OPEN 1 X MIDS AS 2 3 OUTPUT OPEN 25 16942993 DSK13 MASTER INDEXED 80 RELKEY The OPEN statement references the file by its actual ASCII filespec in the standard operating system format Most of the other file commands refer to the file channel number which is assig
132. MAPed array or array element as an argument if the array has not been either DIMed or previously referenced during program execution The XCALL statement cannot allocate such an array at run time You are free to write a routine using and modifying all of the general work registers A0 A6 and DO D7 and your program may use the stack for work space as required When your subroutine has completed its execution it must return to the run time system by executing a RTN subroutine return instruction E 1REGISTER PARAMETERS The following registers are set up by the run time system to be used as required by the external subroutine They may be modified if desired since they have been saved before the subroutine was called AO Indexes the user impure variable area AO is used throughout the run time system to reference all user variables If the longword at AO 2 AlphaBASIC PLUS is implied A file DSKO 7 35 SBRSYM M68 contains the offsets of AO AO may be used as a work register A3 Points to the base of the argument list A3 may be used to scan the argument list for retrieval of the argument parameters A4 Points to the base of the free memory area that may be used by the external subroutine as work space This is actually the address of the first word following the argument list in memory and if desired may be used to store a terminator word to stop the scanning of the argument list A5 This is the C stack index used by the run time
133. MDEIN t S rcv d c cbc nice Sin ebat p pet ala 10 11 10 4 2 DITOSDO roe etes cita on tut AW o LOU DIS Ud 10 11 1043 DSTO A PMCID D RA aina eani 10 11 10 44 ERAS ud E RE ni dS 10 11 10 45 ERR OO A NE d Manly E ed 10 12 1046 FIBEBEOGCK Q inis scr coe e tem dex EXE 10 12 10 47 GEIKEYOQ cm oet RR RAE EUM TS au c be eee 10 12 WOM MOD TAs is Sects ot wats Sain tee eee ince db dee ER Sa da A 10 13 CHAPTER 11 SYSTEM AND FILE FUNCTIONS 11 1 11 2 11 3 11 4 11 5 11 6 11 7 11 8 11 9 CHAPTER 12 FORMATTING OUTPUT 12 1 12 2 12 3 12 4 BYTE X WORD X AND LONG X 0 0000 eee eee 11 1 DATE 0 fey Ope AS eee eB ee ies 11 2 OX wert ea Guia a dea 11 3 MENA ds Se BIN e ss AO ae as Dd a EE 11 3 MME ae eg ao th ie rh se Se Seg ea ce es Sten ta A ree ie Ue eB Tae Petra ts Se 11 4 COOP mias aa Cu El Pig ee ae EM de 11 4 KILL oie ina tea rS ite Det tN Bato iuris d sta d dee a ir ergo 11 5 RENAME 23 Lam ea uas tae con M e e AR eA 11 6 O IR Rhee a eda qd elei cre ie Rus 11 6 THE USING MODIFIER 1 eur RR we RR Rm 12 1 HOW TO SPECIFY FORMAT STRINGS sslssseesssess 12 3 12 2 1 Formatting a Numeric Field f o o oo 12 3 12 2 2 Formatting a String Field Y o o ooooooo 12 4 12 2 3 One character String Fields o o oooooooo 12 5 12 2 4 Using Decimal Points in Numeric Fields 12 5 12 2 5 Dollar Signs and Numeric Fields 12
134. OR A NEW PROGRAM NEW When you first enter interactive mode there is nothing in memory so you can simply type in your program After being in Interactive Mode for a while if you want to create or load in a new program you should first make sure there is nothing in memory To clear memory enter READY NEW RETURN READY NEW erases the program currently in memory If you do not erase the existing program AlphaBASIC PLUS merges the new program into whatever is in memory If any line numbers from the new program duplicate line numbers of an old program in memory the new lines replace the old AlphaBASIC PLUS User s Manual Rev 02 Page 3 4 Chapter Three 3 4CREATING A PROGRAM E To create a program in interactive mode first make sure you have nothing in memory see NEW above and then begin entering program lines Each line must begin with a line number You do not have to enter the lines in numerical order AlphaBASIC PLUS puts them in order for you For example you might enter 10 INPUT Enter a number NUMEUN 30 PRINT NUM EU 20 PRINT EUR If you make a mistake when you enter a line you see 40 A A X AEA Syntax Error This means AlphaBASIC PLUS did not understand your input The caret points to the part of the line that caused the error Re type the correct line 40 A A A Subroutines called by SUBCALL may be used in Interactive mode but after the subroutine is done it exits you to
135. OR GOTO 500 ON ERROR GOTO TRAP ROUTINE AlphaBASIC PLUS User s Manual Rev 02 Page 17 2 Chapter Seventeen The error routine must then take appropriate action based on the type of error The second form of the statement turns off error trapping by giving a line number of zero or leaving the line number off completely ON ON RROR GOTO 0 RROR GOTO m m Es m E P After executing a statement like the ones above error trapping is off and errors are handled in the normal way We recommend all error trapping routines execute the ON ERROR GOTO 0 statement for all errors your program is not going to fix m If an error occurs within the error trapping routine itself it is processed and the error message within an error recovery routine 17 3ERR X FUNCTION Error in error trapping is printed There is no method to trap errors ERR X returns the following data based on conditions at the time of the error ITI D D Nm ONO wm Il The number of the error detected The number of the last line encountered prior to the error The channel number of the last file accessed Error status number from the JOBERR field of the Job Control Block Using any or all of these functions gives you the information you need to decide what your error recovery routine is going to do ERR 3 returns standard monitor error codes See Appendix G for a list 17 3 1Error Codes Returned by ERR 0
136. ORD to throw errors AlphaBASIC PLUS User s Manual Rev 03 ACTUAL PARAMETER ALLOCATE ARRAY BASIC BINARY BINDING BOOLEAN CALL BY REFERENCE GLOSSARY An expression constant or variable passed to a function in a function call The function defines a FORMAL PARAMETER see below at compile time and the actual parameter is substituted into the formula at run time The process of setting aside an amount of disk memory for a specific purpose A structure of data such that each piece of data each variable follows each other in a logical accessible order The data is ordered sequentially i e one two three Beginners All purpose Symbolic Instruction Code Data in the form of a series of Os and 1s This is how data is represented at the lowest level of the computer An association of a variable with a value Whenever you use an assignment statement such as A 5 The value in this case 5 is bound to the variable in this case A That variable contains that value until it is changed by another assignment statement An operation resulting in a TRUE or FALSE condition Thus a Boolean operator compares two expressions and returns a value of TRUE or FALSE depending on how they compared Is a way of associating an ACTUAL PARAMETER with a FORMAL PARAMETER Subprograms use call by reference if the actual parameter is a variable preceded by the atsign The purpose of call by reference is to have a
137. Page 6 8 Chapter Six The better way of totaling is to add all the smaller numbers together before adding that intermediate result to the larger number READY 10 SUM 1E14 20 SUM1 0 30 FOR I 1 TO 100 40 SUM1 SUM1 1 0 50 NEXT 60 SUM SUM SUM1 70 IF SUM SUM1 PRINT Loss of precision ELSE PRINT OK 80 PRINT SUM RUN OK Note that if the smaller number was smaller than the example used the second way of dealing with the additions may not even be sufficient it all depends on the ratio of the larger to the smaller number and the number of significant digits held in the binary floating point representation of the larger number Example 3 Even storing innocuous looking decimal fractions with only a few decimal places such as two decimal places for many currency values can result in a very small loss of accuracy which is magnified as more calculations are done This program has two subtle bugs even for small amounts MAP 1 FPT F 6 MAP 1 INT VALUE I 4 INPUT Enter monetary value FPT INT VALUE FPT 100 The conversion from ASCII from the user s input to floating point may not be exact The conversion to four byte integer is done by converting the result of a floating point multiply operation which will exacerbate any loss of precision already encountered For example if the value input was 200 66 the value stored could be 20065 The result of the ASCII conversion an
138. Page H 4 Appendix H When RUNP is executing the memory map in the partition looks like the following Possible command file area A Minimum of MINF Free Area y n z Stack grows downwards Minimum of MINS V Maximum of MAXS bytes Heap grows upwards v ME Sere TM DSECT Area RUNP LIT OG LIT The size of the memory module that contains the C Stack and Heap is controlled by the MINS and MAXS settings in the BPR file The size of the area left free at the top of memory is controlled by the MINF setting in the BPR file When RUNP initializes it allocates a memory module for its DSECT area t then allocates a memory module for the C Stack Heap area The size of the module is determined in the following way e ook at the size of free memory in the partition If less than MINS MINF DELTA bytes are left RUNP aborts with a STACK HEAP NO MEM error elf sufficient bytes are left provisionally subtract MINF bytes from the size of the free area If the result is more than MAXS allocate the Stack Heap module with a size of MAXS bytes thereby increasing the size of the free area above MINF bytes If the result is less than MAXS bytes allocate the Stack Heap module with the size of the result leaving MINF bytes free H 2 4RUNP S Use of the Stacks Heap and Free Area The Heap is used for allocating memory for such things eAlphaBASIC PLUS s Arithmetic Stack The size o
139. Page Index 16 Status variable iic b xS 19 3 to 19 5 STEP io rs sod wae sey ptiernh eo reete r e 9 7 9 28 STOP eros 4 5 9 29 Stopping a prograM ooccccccccoo 9 6 SEA a a e e 7 7 10 10 String arguments 2 00 10 1 String conversion Llsus 7 4 Sing dala 3324645 es A dapes 14 5 String functions so vs ccv da 10 5 String variables eot Re 14 5 BIOS oo shard ase heh pube 8 Sab a Rests ene 9 4 DMMOS ci 6 12 Including quotation marks 6 12 STRIPS 4 ree c prote eques 10 10 STRSIZ ec doa teer nb ret FP PI 9 4 9 29 Structured program s saesae ssena 5 2 SUBCALE 25e ann o PS eed a 16 5 Argument passing 16 8 Arguments i2eee2a8d etic ieee hat hs 16 8 SUBEND Lirica a od deg aye ee Nee 16 5 16 9 Subprogram aa 16 1 16 3 16 5 22 9 ALQUIMGNIS stereo 16 7 Name iei sese eO ERR awe a ae 16 7 Parameters is sa dk 16 7 Saved environment 16 11 Subprogram name 16 7 Subprograms SPGextension 16 5 SAMA os wk Us es 16 5 CHAIN ata cdo detente hs 16 11 Defining ded e o a e s 16 5 END cic cse Een Ae Shut tend Sve ie 16 9 Error trapping uer scrib aries 16 9 External viii e 16 5 Internal 4 vs rea c x b ri ad 16 5 Search path emir p RES 16 6 Subroutine ooooooo ooo 9 6 9 9 Library Senna xe Rt E E 4 LINKING iia ico Te es 1 2 Loading ec a dd EM ERR 18 2 Program headers E 4 SUDSOHDIS C7 s resa e I
140. SIC PLUS supports three basic classes of variables numeric character and unformatted The first two classes are further subdivided eNumeric variables are variables whose contents are a number which can be used in mathematical calculations eStrings consist of zero or more consecutive characters eUnformatted variables are treated as containers of consecutive bytes without interpretation Each of these classes are described below 6 2 1Numeric Variables The numeric variable class has two subclasses whole numbers and floating point numbers eWhole numbers integers which cannot have a decimal fraction associated with their value Floating point real numbers which have a decimal fraction associated with their value 6 2 1 1Integers An integer variable can be one of two types eUnsigned integers which can hold integer values greater or equal to zero eSigned integers which can hold both positive and negative values as well as zero Thus 12 is an example of an integer and you can use either a signed or unsigned integer to hold its value The value 19 is another integer but can only be held in a signed integer variable The value 65 3 is a floating point number and cannot be held exactly in an integer the decimal fraction part 0 3 would be truncated and lost AlphaBASIC PLUS uses both types of integer variables AlphaBASIC PLUS User s Manual Rev 02 Variables Page 6 5 6 2 1 1 1True Integers True integ
141. STRSIZ statement to reset the default string size or use a MAP statement for the string variable specifying the size you need See below for information on STRSIZ If a user of your program does not enter as many items of data as are expected by the variables in the INPUT statement AlphaBASIC PLUS displays a double question mark to ask for more For example AlphaBASIC PLUS User s Manual Rev 02 Page 9 16 Chapter Nine INPUT A B CUN 1 2 ET 22 3 RETURN The direct statement asks for three items of numeric data Because only two were entered AlphaBASIC PLUS responds with to ask for the third value Be careful to correctly enter the type of data the variables in the INPUT statement expect If you enter a string for a numeric variable AlphaBASIC PLUS sets that variable to zero For example INPUT A1 RETURN ME RETURN PRINT Al EU 0 If you enter a numeric value for a string variable AlphaBASIC PLUS accepts it as a string Therefore your programs should make sure the correct data has been entered If a value has not been assigned to a variable AlpghaBASIC PLUS assumes the variable contains a zero if a numeric variable or a null if a string variable If you press in response to an INPUT statement request for data AlphaBASIC PLUS leaves the variable being input set to a zero or null if a value has not yet been assigned or to the value previously assigned to the variable The same is true for pressing c3 J Cc
142. Scaled Arithmetic Page 13 3 For example if you want to handle numbers with three digits to the right of the decimal point a scaling factor of 2 leaves one digit to the right of the decimal point and a scaling error can still occur So if you are using numbers with a fractional part of two digits use a scaling factor of 2 if the fractional part is three digits use 3 etc Floating point numbers stored in files by the sequential output PRINT statement are unscaled and output in ASCII without problems Floating point numbers written to random access files by using WRITE are not unscaled first any program reading this file as input must either be operating in the same scaling mode in which the data was written or else must apply the scale factor explicitly to all values from the file Integer and string values are never modified regardless of the scaling factor currently in use 13 2HOW THE SCALING FACTOR WORKS E All of the conversions we discuss in this section are done automatically by AlphaBASIC PLUS This section merely talks about the background theory of scaling numbers The scaling factor represents the number of decimal places the 11 or 15 digit window is effectively shifted to the right in any floating point number For example the most common application is in a business environment where the scaling factor of 2 is used to give absolute 11 or 15 place accuracy to numbers which extend 2 places to the right of the decimal poin
143. T IS BASIO corta di Gas Shoe eey eee ERE eR E 1 2 1 3 HOW IS ALPHABASIC PLUS SPECIAL 000 4 1 2 1 4 WHAT CAN ALPHABASIC PLUS DO ooo 1 3 1 5 WHAT TYPES OF DATA DOES ALPHABASIC PLUS SUPPORT 1 4 1 6 THE ALPHABASIC PLUS SYSTEM 02 eee eee ee 1 4 1 7 EXTENSIONS USED WITH ALPHABASIC PLUS 1 5 1 8 WHAT DOES AN ALPHABASIC PLUS PROGRAM LOOK LIKE 1 5 1 9 GRAPHICS CONVENTIONS 2 00 24 06 RR eee eI 1 6 PART TWO THE AlphaBASIC PLUS SYSTEM CHAPTER 2 GENERAL INFORMATION 2 ONE NUMBERS sean ded ROV E OH rr Noe RR RU Rs 2 1 2 2 LABELS iras vete de Edd RN T URDU eM o edid 2 2 2 3 COMMENTS REMAND 2 603 nes cas e mA ene ow ea RE 2 2 2 4 MULTIPLE STATEMENT LINES 00 0 e eee eee 2 3 2 5 CONTINUATION LINES ee bts hien 2 3 2 6 MEMORY ALLOCATION i235 es EXER Remi SESS ER 2 4 2 7 SEARCHING FOR A LIBRARY 0 00 e eee eee 2 4 CHAPTER 3 INTERACTIVE MODE 3 1 WHAT IS INTERACTIVE MODE 0000 ee 3 1 3 2 DIRECT STATEMENTS 220 22 2 tout RARE EROR Medea eet egnacs 3 3 3 3 CLEARING MEMORY FOR A NEW PROGRAM NEW 3 3 3 4 CREATING A PROGRAM iua tad a aa EAR 3 4 3 5 DELETING PROGRAM LINES DELETE 000005 3 4 3 6 SAVING A PROGRAM SAVE unica ag RE ERE eee 3 5 3 7 LISTING A PROGRAM LIST o cede ad Soe esa yee eae E 3 7 3 8 COMPILING A PROGRAM 24 2 24 Gi eke eu pela 3 7 3 8 1 Compiler ODplOnSs 25 cor ec Ee S Ren EE b
144. TE Check if numbers are valid FLAG 1 THEN GOTO RE START PRINT A B A B INT INPUT Enter two numbers to be divided A B GOSUB VALIDATE Check if numbers are valid FLAG 1 THEN GOTO RE START INT A B TA B INT PRINT Th th th that s all folks END VALIDATE Subroutine to validate the data IF A lt 0 OR B lt 0 OR A gt 100 OR B gt 100 THEN PRINT Error incorrect number entered in input FLAG 1 ELSE P Pi G O n cece ol I J UH Aw FU LAG 0 ENDIF RETURN Note an END statement separates the main program from the subroutine otherwise AlphaBASIC PLUS executes VALIDATE again after printing Th th th that s all folks and you see a RETURN without GOSUB message Also note the use of GOSUBs helps to modularize your programs and thus makes them easier to design and maintain Even before you completely flesh out your programs you can insert dummy routines to later contain complete code For example This program is an example of a dental package PRINT Welcome to the Dr Plak Rental Dental Package PRINT GOSUB INIT Perform initialization of data files GOSUB MENU Ask user to pick func
145. TION the last statement PRINT DEDUCTION can never be executed Do not use a GOTO from a location outside a loop or function to a location inside a loop or function a FOR NEXT DO LOOP etc This causes a compiler error 9 19IF THEN AND ELSE The IF statement may be either in multi line form IF expression THEN statement s or label s line s statement s or label s line s AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 13 or in single line form IF x THEN y ELSE z If there is no statement or label line after the IF expression on the first line it defines a multi line IF statement The IF statement evaluates expression and conditionally performs the specified operation s in response to that evaluation The conditional processing features in AlphaBASIC PLUS give a wide variety of formats Some of the acceptable format combinations are IF expression THEN line IF expression THEN GOTO line label IF expression GOTO line label IF expression THEN line ELSE GOTO line label IF expression THEN GOTO line label amp ELSE GOTO line label IF expression THEN statement IF expression statement IF expression statement ELSE statement IF expression THEN statement ELSE statement
146. TOMER ID MAP2 NAME S 13 MAP2 ID NUM F MAP2 SEX B MAP1 PRODUCT INVENTORY CUSTOMER ID MAP2 BRAND S 13 MAP2 PARTNO F 6 MAP2 RESALE B 1 The MAP statements above allocate the variable CUSTOMER ID which uses a total of 20 bytes Then it allocates the variable PRODUCT INVENTORY also using 20 bytes and specifies by using the CUSTOMER ID origin parameter PRODUCT INVENTORY occupies the same space in memory as CUSTOMER ID The following statements define three areas which all occupy the same memory area but which may be referred to in three different ways 100 MAP1 INVENTORY 110 MAP2 INDEX S 28 120 MAP2 ITEM S 30 200 MAP1 ADDRESS INVENTORY 210 MAP2 STREET S 24 220 MAP2 CITY S 14 230 MAP2 STATE S 4 300 MAP1 PRICE CODE INVENTORY 310 MAP2 UNIT 320 MAP3 CODE B 2 330 MAP3 PRICE F 6 Statements 100 to 120 define a map level with two string elements a total of 58 bytes in memory Statements 200 230 define an area with three string variables for a total of 42 bytes Normally this area follows the INVENTORY area in memory but the origin parameter in statement 200 causes it to overlay the first 42 bytes of the INVENTORY area instead Statements 300 330 define another map level of a different format one 2 byte binary variable
147. UMBER PRINT The square of NUMBER is ANSWER END AlphaBASIC PLUS User s Manual Rev 02 Page 1 6 Chapter One Notice how the AlphaBASIC PLUS statements used in the program above are English words PRINT INPUT END which give you a good idea of what they do Because of the way AlphaBASIC PLUS handles variable names you can give your variables names that give you an idea of what they are for i e NUMBER and ANSWER You can learn more about the above statements later in the manual 1 9GRAPHICS CONVENTIONS This manual conforms to the other Alpha Micro publications in its use of a standard set of graphics conventions We hope these graphics simplify our examples and make them easier for you to use Unless stated otherwise all examples of commands are assumed to be entered at AMOS command level SYMBOL MEANING Device Name The dev is the three letter physical device code and the n is the logical unit number Examples of device names are DSKO DSK5 WIN1 and MTUO Usually device names indicate disk drives but they can also refer to magnetic tape drives and video cassette recorders filespec File Specification A file specification identifies a specific file within an account A complete filespec is made up of the devn the filename the file extension and the project programmer number For example devn filename ext p pn Or DSKO0 SYSTEM INI 1 4 This
148. UNP to reinitialize itself by using CHAIN RUNP MYFILE The SWA setting in a SPG file is not used by the calling RP file in any way Therefore the calling RP s SWA setting must be sufficient for its own requirements and the requirements of any SUBPROGRAMs it executed In general nesting subprograms requires that the SWA size is set to the maximum requirement of any one subprogram and calling RP file The individual requirements for subprograms at each level of nesting are not totalled to give the overall requirement Both nested user defined functions and multiple user defined functions in one AlphaBASIC PLUS statement require that the SWA size is the sum of the requirements for each user defined function active during the execution of that statement Therefore if one function recurses to five levels and there are two other user defined functions in that statement the SWA requirement is at least six times the requirement for the recursive function plus the individual requirements for the other two functions AlphaBASIC PLUS User s Manual Rev 02 APPENDIX J COMPILER AND RUNTIME OPTIONS During the evolution of AlphaBASIC PLUS its designers made a large number of decisions that defined how the compiler and runtime systems worked In many cases the decisions were influenced by existing practices and backwards compatibility with AlphaBASIC 1 3 and AlphaBASIC 1 4 As always some decisions that were right at the time seem a little less c
149. UR COMPILING Compile time was 0 003 seconds elapsed time was 0 seconds READY AlphaBASIC PLUS User s Manual Rev 02 Page 3 8 Chapter Three In interactive mode you may compile only the program currently in memory The resulting object program RP file is re usable it can be used over and over again and re entrant it may be loaded into system memory so everyone on your system can use the program even at the same time Once the program is compiled the object code resides in memory along with the source program Compiling a program sets all variables to zero and deletes all variables left over because of direct statements If no program is in memory you see the message No source program in text buffer 3 8 1Compiler Options You may specify any or all of the compiler options the system level COMPLP program allows when using the BASICP command These are explained in Chapter 5 You may specify options when you use BASICP to enter interactive mode these options then become the default for that session You may also use the options with the COMPILE statement to effect only that specific compilation 3 9RUNNING A PROGRAM RUN To execute a program enter RUN READY RUN RETURN The program begins running RUN resets all of the variables to zero and all string variables to a NULL value a string containing no characters before running the program If you wish to stop the program during the run pr
150. User s Guide Index Page Index 7 ERR 2Y Jue c ee dos 17 2 ola ET 17 2 ERR 3 Error Codes G 1 ERR A casita tad SNB o Do Dre UU ended 10 12 17 2 EHRMSGUS oo desto xA eoo de 10 11 Error codes Sania Een rw 10 12 Error codes returned by ERR 0 17 2 Error message 0 2e eee 10 11 Error processing vios ES RTI Seb AVS 19 9 Error trapping ues EC AAA 9 20 16 9 17 1 Control vi sv erp E Y ER 17 4 Sample programs 17 4 Even addresses cix es 14 12 Examples of MAP statements 14 9 Exclamation symbol 2 3 Executing command files from BASIC 9 2 EXIT Sebast edt dues bxc ibt n doa 9 7 Exiting interactive mode 3 9 EXPOS ear es 10 2 EXPressIO MIS ra 9 22 Expressions 00 cee eee E 7 1 7 4 8 3 9 22 10 1 Definition Pecan iae o snc o Aet 7 1 Functions with arguments 9 22 Numeric constants 9 22 Numeric variables 9 22 Operator symbols 9 22 String literals 9 22 String variables o o 9 22 EXTENSIONS 1 5 ice UD E 3 6 5 3 DA A ec o uni A rna es 15 18 O tSUeRTSS Orte bs 5 3 SELES oca seh dente TEE waste MEL rd 3 6 5 11 16 1 External assembly language subroutines 9 31 FAG IA God ei aa ada 10 2 Factorial cuida sarta as 10 2 FILE s eee nthe aes ER 22 6 File channels 0000 ee eee 15 2 File fU
151. Z statement in your program to adjust the default string size AlphaBASIC PLUS User s Manual Rev 02 Formatting Output Page 12 5 12 2 30ne character String Fields The exclamation mark identifies a one character string field AlphaBASIC PLUS replaces the exclamation mark with a corresponding string If the string constant or string variable contains more than one character AlphaBASIC PLUS ignores any characters past the first For example STRSIZ 40 MASK The temperature is HELLO tl PRINT USING MASKS 50 F 10 C PRINT USING MASK 68 F 20 C PRINT USING MASKS 86 F 30 C PRINT USING MASK 104 F 40 C prints The temperature is 50F 10C The temperature is 68F 20 The temperature is 86F 30C The temperature is 104F 40C If no string is available to be substituted for the symbol AlphaBASIC PLUS prints the symbol instead For example if we took our program above and removed the first F from the PRINT USING expression list the first line of our display becomes The temperature is 50 10 12 2 4Using Decimal Points in Numeric Fields You may include one period within a numeric field to specify where a decimal point is to appear in the formatted number For example READY PRINT USING 2345 502 1100 657 200 6t 2345 50 1100 66 200 00 If the number specified contains more digits to the right of the decimal point than the format string AlphaBAS
152. a eThe formatting characters you can use eHow to use tab functions to control the output of data to the terminal screen 12 1THE USING MODIFIER The USING modifier lets you format numeric or string data by specifying a format string sometimes called an editing mask Although you can use the USING modifier to store the formatted data in a string variable you may also use it in combination with the PRINT statement to send the formatted data to a terminal display or to a file For information on PRINT see Chapter 9 By formatting data we mean the process of adjusting the appearance of data that is by inserting commas or spaces so it fits the pattern of a specific format string It might help to think of the format string as a template or pattern with which you are going to control the format of your data The USING modifier allows you to apply the format string to your data Using format strings and USING you can do such things as el ine columns of numbers up by their decimal points einsert dollar signs and commas into numeric data to represent dollar amounts el ine up numeric and string data within specified fields eGenerate and print leading zeros for numeric data ePrint asterisks instead of leading spaces AlphaBASIC PLUS User s Manual Rev 02 Page 12 2 Chapter Twelve ePrint numeric data in exponential form and many other things The sections below talk about the special formatting characters within the format string allow
153. a program 5 11 Running an interactive program 3 8 BUND a tado Ed 1 5 5 11 9 28 15 9 22 10 HUBNPEDT i indo ensem y dec ee nes 1 4 Runtime options o o occooooooo 5 11 SAVE oe dt totes dota aeo s Mri ed 3 5 Saving an RP file 3er RREXE 3 6 Saving an interactive program 3 5 SCALE fic twhieaviee leads 9 27 13 2 22 8 Scaling factor lara tr be i 13 2 Screen handling codes 12 9 D 1 SEARCH acie tat eot Ene 22 5 Search palb o oooooccoocococooo oo 2 4 Searching for a Library 2 4 Searching for disk files 11 4 15 15 Semicolon symbol 8 1 9 22 Sequential files 15 3 Append 229a retine ee eh er ES 15 3 n DUE dese pus ERE PIU RESI 15 4 Oulp t S enter E RERO RENE 15 3 SONOS cesi id ect etae e crete ese wee 10 4 cl pp Pm 10 4 SIGNIFICANCE sico add e 9 27 22 8 SIN lt a bene VERE 10 4 Single line user definable functions 20 1 Single step 0 02 eee 3 1 4 4 SLEEP n s ebd rper eee RE e EE 9 28 Source programs ooo 3 6 4 3 9 1 Readability 4 2545 rd EIE us C 2 SPACE tania tada e Lens Bie rend 10 9 SPAN BLOGKS 5 c000 ira ad 15 5 15 17 Spanning blocks sso rrr wi 15 5 Speed A A Wwe RE eee eee C 2 SP NN 10 4 Square TOOL xs asco ee ede EA RS 10 4 Statement modifiers 9 1 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index
154. abbreviation represents an account on a disk where you can store files and data An actual disk account number looks like this 100 2 or 1 4 Disk account specifications are sometimes referred to as Project programmer numbers Braces are used in some examples to indicate optional elements of a command line In the example DIR switch the braces tell you switch is not a required portion of the DIR com mand line continued AlphaBASIC PLUS User s Manual Rev 02 Introduction Page 1 7 SYMBOL MEANING The slash symbol precedes a command line switch or option request For example DIR WIDE 3 tUm This command requests a directory display of the disk account you are currently logged into The switch WIDE 3 indicates you want the display to be three columns wide Bold text in an example of user computer communication represents the characters you type Text like this in an example of user computer communication represents characters the computer displays on your terminal screen In our examples the key symbol appears whenever you need to press a certain key on your terminal keyboard The name of the key you need to press appears inside the key symbol like this Gua f you need to press the TAB key you would see 8 or the ESCAPE key 5 amp 9 Sometimes the ESCAPE key is labeled ESC or ALT MODE cra ev This indicates a control sequence you press on the keyboard Press and hold it
155. able can be specified by appending a to the variable s name or by defining the variable in a MAP statement using the s data type in which case the trailing dollar sign in the name is not required but can be used if needed If the dollar sign option is used without a MAP definition the maximum size of the string is governed by the value associated with the STRSIZ statement last encountered by the compiler If no STRSIZ statement has been encountered the default size is 10 characters A MAP statement definition also defines the size of the string String variables can be manipulated by string functions such as LEFT RIGHTS etc as described in Chapter 11 Strings can be concatenated joined together by the operator and pulled apart by the functions shown in Chapter 11 and by the substring modifying features described in Chapter 8 String variables can be used in arithmetic expressions as described in Section 7 5 on mode independence AlphaBASIC PLUS User s Manual Rev 02 Page 6 10 Chapter Six 6 2 3Unformatted Variables AlphaBASIC PLUS treats unformatted data as a set of consecutive bytes of a specified size The maximum size of an unformatted variable is 65 535 bytes Unformatted variables are defined by using a MAP statement with a data type of x which automatically happens if an unformatted variable is MAPed with sub variables at a lower MAP level AlphaBASIC does not interpret the contents of an unformatted variable in any way
156. ables are interlaced with the HEIGHT variables giving WIDTH 1 HEIGHT 1 WIDTH 2 HEIGHT 2 WIDTH 10 HEIGHT 10 There are also ten unformatted variables AREA 1 through AREA 10 each containing the respective pairs of WIDTH HEIGHT variables in tandem Referencing one AREA variable references the unformatted item composed of the WIDTH HEIGHT pair of the same subscript When using MAP variables keep these points in mind eUse an unformatted variable to group multiple mapped variables together elf printing a string or unformatted variable any floating point or binary variable mapped beneath it doesn t display properly eWhen using string variables don t assign a size much larger than you need for the variable this is a waste of memory space AlphaBASIC PLUS User s Manual Rev 02 Mapping Variables Page 14 11 eUse only the variables you need For example if you want an address do not break down the address into partial strings unless you need to refer to that part of the address The more variables you define the more memory you use 14 4USING MAPPED DATA WITH DATA FILES You may often use MAP statements to define groups of information to be transferred in and out of random files Because of the structure of sequential files it is difficult to input and output mapped variables as groups The information only transfers correctly if all of the variable information is carefully padded to the proper lengths Therefore i
157. above used the PRINT statement to print formatted data Remember you may also format a numeric value without displaying it by using the USING modifier without the PRINT statement For example AS B USING C The statement above formats the number in B using the format string in C and leaves a string result in A This format of the USING modifier is only for formatting numeric data Also note even though we are formatting numeric data the result is always a string This type of format allows you to create headings and image lines you use more than once and to inspect and manipulate formatted data before printing it You may not use the USING modifier recursively That is you may not use a format string that is itself the result of a USING modifier For example if you have specified CS Hitt FH you may not say AlphaBASIC PLUS User s Manual Rev 02 Formatting Output Page 12 9 PRINT CS USING 4 When using the PRINT USING format remember PRINT USING differs from the regular PRINT statement in that the use of semicolons to separate the elements of the print list has no effect on the spacing of those formatted elements 12 4TAB FUNCTIONS The TAB function can be used to control various functions of your terminal The TAB function is only used in a PRINT statement It operates in the traditional manner when supplied with only a single numeric argument such as TAB X In this case the function
158. ag value of 1 Wednesday April 1 1995 04 53 23 PM Here are two examples of ODTIM READY PRINT ODTIM 0 0 2294 Wednesday January 15 Display date Display time OPEN 1 INVEN INPUT 1 Last I 0 DAT INPUT nventory DT DT O returns an ouput in the following format 1994 11 00 00 AM Date Time of day IM Last IM Last Inventory Date Time of Day 694 Inventory Date Time of Day 3073 PRINT Last inventory was iDisplay date at Display time ODTIM will work correctly with dates from March 1 1900 to December 31 2099 AlphaBASIC PLUS User s Manual Rev 04 CHAPTER 11 SYSTEM AND FILE FUNCTIONS AlphaBASIC has a unique group of operators called system functions which allow you to eAccess various system parameters eAccess the computer s input output ports eAccess physical memory eWork with external files System functions use a format similar to that used by standard functions with the reserved word representing the desired function followed by optional arguments enclosed within parentheses The major difference is the reserved word of a system function may appear on the left side of an assignment statement When a system function is used on the left side of the equal sign in a statement it outputs the result of that function to a specified place System functions used within expressi
159. ally it applies MAX to the parts of the expression i e 1600 MAX 25 5556 and returns the greater or maximum value of the two sub expressions 1600 The order of evaluation of the terms in the expression and the rules of mixing variable types are described below 7 3LOGICAL OPERATORS The logical operators AND OR XOR EQV and NOT are useful in conditional statements such as IF THEN statements to evaluate and compare expressions The AND statement compares two expressions If both expressions are TRUE the IF condition is also TRUE If either or both statements are FALSE the IF condition is FALSE For example AlphaBASIC PLUS User s Manual Rev 02 Expressions and Evaluation Page 7 3 QUESTION INPUT Enter a number between 0 and 100 NUMBER IF NUMBER gt 0 AND NUMBER lt 100 THEN GOTO START ELSE PRINT Number incorrect GOTO QUESTION ENDIF START If either of the expressions NUMBER gt 0 Or NUMBER lt 100 are FALSE the program above goes back and asks the question again We can demonstrate OR with a similar section of code QUESTION INPUT Enter a number between 0 and 100 NUMBER IF NUMBER lt 1 OR NUMBER gt 99 THEN PRINT Number incorrect GOTO QUESTION ENDIF With OR the IF statement is TRUE if any of the expressions are TRUE With XOR which m
160. am and instructs execution to return back to the calling program If an END statement is encountered in the subprogram the entire program will be terminated The SUBEND statement can take an optional parameter of an error code If a non zero number is specified an AlphaBASIC PLUS error corresponding to theat number is propagated back to the calling program This can be used to control error handling discussed below The parameter can be either a literal or a variable such as ERR 0 16 2 5Error Handling in Subprograms Each subprogram has its own environment and so can have its own set of ON ERROR statements If none are defined and an error occurs the program is terminated even if the calling program has an ON ERROR set active The terminating message will specify the error type the line number of the error if set and the name of the subprogram if it was an external subprogram or the name of the RP file if it was an internal one If a subprogram has an ON ERROR set and an error occurs control is passed to the line or label specified in the ON ERROR line ERR 0 will hold the error code and AlphaBASIC PLUS User s Manual Rev 02 Page 16 10 Chapter Sixteen ERR 1 the line number of the error in the subprogram if set After executing some code the subprogram can return to the calling program if it wishes by executing a SUBEND If the SUBEND either has no parameter or a parameter with a zero value is specified the error settin
161. am runs eContinuing a program after a BREAK eExiting from a program run using Control C el oading programs into BASIC from the disk eUsing the single step feature to debug programs 4 1INTERRUPTING A PROGRAM The BREAK command can RUN BREAK aid you in finding errors in your programs It can be used to set clear and display breakpoints For example REAK REAK 100 REAK 30 50 R R REAK 30 FAK 20 120 tU tU UU tU tU Lists all breakpoints currently set Sets a breakpoint at line 100 Sets breakpoints at lines 30 and 50 Clears the breakpoint at line 30 Sets a breakpoint at line 20 clears the one at line 120 When you set a breakpoint you are asking interactive AlphaBASIC PLUS to stop just before the line you specified When the program is run it proceeds until it hits the breakpoint Then you see i At this point you can enter Break at line x interactive mode commands proceed line by line using the single step feature see below or enter direct statements The value of being able to enter direct statements is you can find out what values the variables have or even change those values For example AlphaBASIC PLUS User s Manual Rev 02 Page 4 2 Chapter Four READY RUN RETURN Break at line 40 PRINT A UN 5 Here the value of the variable A is 5 before line 40 is executed If your program is not giving you the answer you expect you can use br
162. andom number generator 9 36READ RESTORE AND DATA The formats are READ variablel variable2 variableN RESTORE DATA datal data2 dataN These calls let data be an integral part of the source program with a method for getting this data into specific variables in an orderly fashion DATA statements are followed by one or more literal values that is not variables separated by commas String literals need not be in quotes unless the literal data contains a comma All data statements are placed into a dedicated area in memory no matter where they appear in the source program Do not place comments on a DATA statement line the comment may be interpreted as data READ statements are followed by one or more variables separated by commas Each time a READ statement is executed the next item of data is retrieved from the DATA statement pool and loaded into the variable named in the READ statement If there is no more data left in the data pool the program can only continue to read data if a RESTORE statement is executed which reinitializes the reading of the data pool from the beginning Otherwise you see an out of data message and the program stops READ accepts the E and D exponential markers for AMOS or IEEE floating point variables but not alternate radix specifiers Here are some forms READ and DATA may take DATA 1 DATA READ A READ A READ C 2 3 B 4 ONE STRING 4 4
163. anual AlphaBASIC PLUS User s Manual Rev 02 Page E 4 Appendix E E 4FREE MEMORY USAGE When the subroutine is called indexes A4 and A5 mark the beginning and end of the free memory currently available for use as work space This area is not preserved by the run time system and the subroutine must not count on its security between XCALL statements Note the word at A4 may be used as the first word but the word at WA5 is the base of the arithmetic stack and must not be destroyed The last word of actually free memory is at 2 A5 The run time system has its own internal memory management system and does not conform to the operating system memory management method Registers A4 and A5 point to the free area between the heap and C stack as explained in Appendix H This is the same as for AlphaBASIC In AlphaBASIC PLUS only you may be able to allocate standard AMOS memory modules via the GETMEM and GETIMP monitor calls if sufficient free memory is available at the top of your memory position This area can be set aside by using the MINF setting in a BPR file as discussed in Appendix H E 5LOCATING OPEN FILES A standard library routine FLSET is provided in the system subroutine library SYSLIB LIB to locate the DDB associated with a file opened by an AlphaBASIC PLUS program For more information see your AMOS Monitor Calls Manual E 6PROGRAM HEADERS All AlphaBASIC PLUS subroutines must contain a program header at the start of th
164. apital Letter Thorn Latin Small Letter Sharp S Latin Small Letter A With Grave Latin Small Letter A With Acute Latin Small Letter A With Circumflex Latin Small Letter A With Tilde Latin Small Letter A With Diaeresis Latin Small Letter A With Ring Above Latin Small Ligature AE Latin Small Letter C With Cedilla Latin Small Letter E With Grave Latin Small Letter E With Acute Latin Small Letter E With Circumflex Latin Small Letter E With Diaeresis Latin Small Letter With Grave Latin Small Letter With Acute Latin Small Letter With Circumflex Latin Small Letter With Diaeresis Latin Small Letter Eth Latin Small Letter N With Tilde AlphaBASIC PLUS User s Manual Rev 02 Also Known As Page F 7 Type See Note Lu Lu Lu Sm Lu Lu Lu Lu Lu Lu Lu LI LI LI LI LI LI LI LI 2 LI LI LI LI LI LI LI LI LI LI LI Page F 8 Char acter O gt O Also Octal Called Value 362 363 364 365 366 367 370 371 372 373 374 375 376 377 Notes Appendix F Decimal Hex ISO IEC 10646 1 1993 E Also Known As Type See Value Value and Unicode 2 0 Name Note 242 F2 Latin Small Letter O With LI Grave 243 F3 Latin Small Letter O With LI Acute 244 F4 Latin Small Letter O With LI Circumflex 245 F5 Latin Small Letter O With LI Tilde 246 F6 Latin Small Letter O With LI Diaeresis 247 F7 Division Sign Sm 248 F8 Latin Small Letter O With LI Stroke 249 F9 Latin Small L
165. apping routine statement The optional DEFAULT clause is executed if no matches are found and if no transfer of control is found in a previous matching case statement If no DEFAULT clause is specified and no matches occur control passes to the statement after ENDSWITCH Here is an example of SWITCH SWITCH Stock Number CASE 00001 GOSUB Print Shipping Label Inventory 00001 Inventory 00001 1 EXIT CASE 00002 GOSUB Print Mailing Label Inventory 00002 Inventory 00002 1 EXIT CASE 00003 GOSUB Print Pickup Order Inventory 00003 Inventory 00003 1 EXIT DEFAULT PRINT There is no such Stock Number GOTO Re enter Number ENDSWITCH Each constant can have a range of values For example CASE 12 match only on 12 CASE 11 match on 11 or less CASE 13 match on 13 or greater CASE 2 14 match from 2 to 14 inclusive CASE a g match from a to g inclusive CASE 1015 match this octal value to ASCII decimal value 013 Values such as a are character constants which hold a decimal ASCII value a equals 97 for example Values such as 1015 are in octal notation and translate to an ASCII decimal value 013 in above example See Chapter 7 for more on character constants You may also use multiple CASE statements to select values not connected in any pattern For example AlphaBASIC PLUS User s Ma
166. as an addition operator for numeric operations and as a concatenation operator for string operations The value of 34 5 is equal to 39 but the value of 34 5 is equal to the string 345 The operation of the plus symbol is unambiguous but may take a little thought to figure out in a given situation A few examples might help If the first operand is numeric and the second is string the second is converted to numeric form and addition is done 34 5 39 If the first operand is string and the second operand is numeric the second is converted to string and concatenation is done 34 5 345 The above two examples apply only when the compiler is not expecting a particular type of variable or term This generally occurs only in a PRINT or IF expression such as PRINT 34 5 At other times the compiler expects a specific type of variable the conversion of the first variable is then performed prior to inspecting the operator plus sign What the plus sign does then depends upon that first variable if the variable is a numeric one the plus sign does addition if string it concatenates this is the one case where parentheses will not change the operation the plus sign obeys the type of variable it is being assigned to regardless of any parentheses In the following example NUM 5 34 4 The multiplication operator forces us to expect a numeric term to follow The 34 string is therefore immediately converte
167. as long as the first character is alphabetic Apostrophes and underscores can also be used This is another feature which makes AlphaBASIC PLUS well suited for business applications Since the source code is compiled and need not be in memory when the program is run the length of the variable name is not a significant concern Label names may also be used to identify points in the program for GOTO and GOSUB branches Label names are alphanumeric and help to clarify the program structure Some examples of label names EXIT ERROR EVALUATE ANSWER PROCESS_DATA Variable names and data formats are discussed in more detail in Chapter 6 1 6THE ALPHABASIC PLUS SYSTEM The AlphaBASIC PLUS system consists of three programs BASICP LIT A BASIC PLUS module that combines an interactive compiler with a run time package to provide an interactive BASIC environment COMPLP LIT AMOS level disk based AlphaBASIC PLUS compiler RUNP LIT AMOS level AlphaBASIC PLUS run time package AlphaBASIC PLUS User s Manual Rev 02 Introduction Page 1 5 Each of these programs has a corresponding RTI file which is used for internal initialization when the LIT file executes for the first time You use RUNP and COMPLP from monitor command level to run and compile AlphaBASIC PLUS programs that exist as disk files You use the BASICP command when you want to use AlphaBASIC PLUS in interactive mode With these three programs you ca
168. atement it applies to The control variable may be omitted in the NEXT statement in which case the control variable of the previous FOR statement is the one incremented control variable is incremented or decremented in units indicated by the STEP AlphaBASIC PLUS User s Manual Rev 02 Page 9 8 Chapter Nine E statement if STEP is used If no STEP modifier is used the step value is assumed to be positive 1 AlphaBASIC PLUS does an initial test of the control variable at the FOR statement This means that if the condition is true the statements within the loop are not executed FOR and NEXT statements are illegal as direct statements in Interactive Mode except when put on the same multi statement line For example this line is valid FOR I 1 TO 10 PRINT I NEXT I Here are some samples of the different forms FOR NEXT loops may take FOR COUNTER 1 TO 10 PRINT The COUNTER IF COUNTER 2 INT COUNTER 2 THEN PRINT COUNTER is even ELSE PRINT COUNTER is odd ENDIF NEXT COUNTER 10 Enter the date of the first Sunday in the month 20 INPUT LINE DAY 30 PRINT The Sundays this month are on these dates DAY 40 FOR A DAY 7 TO 31 STEP 7 50 PRINT A NEXT A FOR I 10 TO 1 STEP 1 PRINT I NEXT Loops within loops are legal and are called nested lo
169. atement may consist of several sub variables mapped by using MAP2 statements Each of those variables may in turn consist of several variables mapped by using MAP3 statements And so on down to MAP16 Nested numeric MAP statements cause an error You cannot specify a numeric variable such as a floating point and then have another numeric variable defined below it with a lower MAP level You can only nest a numeric variable within string or unformatted type variables MAP16 represents the lowest level or innermost variable MAP1 represents the highest level variable You do not need to map levels in strict numeric sequence for example a MAP5 statement may follow a MAP3 statement without an intervening MAPA statement You may refer to variables at any level An example may help to clarify this idea MAP1 PATIENT INFO y y y y MAP2 NAME ADDRESS INSURANCE y y y y y y y MAP 3 LAST FIRST STREET NUM CITY AlphaBASIC PLUS User s Manual Rev 02 Page 14 4 Chapter Fourteen The diagram above shows three levels of variables mapped with MAP1 MAP2 and MAP3 statements You may refer to the level 1 variable PATIENT INFO as a whole or may refer to one of the variables on levels 2 and 3 representing sub groups of the variable PATIENT INFO such as NAME ADDRESS or STREET When referring to any unformatted variable in the group you are actually referring to the information in all of the variables
170. ation on the left is done before the division The only exception to this rule is exponentiation which is done right to left For example 5 2 4 In this case AlphaBASIC PLUS raises 2 to the fourth power first and then raises 5 to the sixteenth power 7 5RULES OF CALCULATION After the precedence rules have been invoked to sort out the order of evaluation of the expression AlphaBASIC PLUS follows these rules for calculations 1 Binary variables are converted to real numbers before use and back after use 2Single precision IEEE variables are converted to double precision variable before use and back after use 3For a given operation the operation is done in the larger of the two formats of the operands and the result is left in that format unless the operation forces conversion to a specified format mathemnatical functions will automatically at compile time select an AMOS or an IEEE floating point version to maintain precision Each mathematical function described in Chapter 10 exist in both the AMOS floating point as well as IEEE double precision forms The compiler will select the appropriate choice so as to achieve the required degree of precision 4Numeric literals in the source code are treated as integers unless they have a trailing decimal point or an exponent marker 5AII logical operations such as AND OR NOT etc cause values to be converted to 5 byte binary variables before the logical operation is performed
171. ave been set into an object file by using the R switch with a filename RUNP R MYFILE This produces a list of statistics and option settings for MYFILE and confirms whether or not the version of RUNP can be used with this file J 4ALTERNATIVE METHOD OF OPTION SPECIFICATION Currently COMPLP and RUNP have a maximum of 64 possible options only a few of which are defined So entering a small number of options on a list is simple But as the possible list grows it becomes impractical to type in the list on the command line with the P switch Either PRAGMA settings can be used or use can be made of the PX switch The PX switch lets you enter the required list in a shorthand way AlphaBASIC PLUS User s Manual Rev 03 Compiler and Runtime Options Page J 3 gf PX1 number is used to enter any and all options from 1 through 32 inclusive PX2 number is used for options 33 through 64 inclusive To calculate the correct number to enter you need to understand binary arithmetic Each option number sets a bit in a 32 bit number and all the unrequested options clear a bit in the same number The decimal value of the resulting 32 bit number is the value to enter for number In the example below the options are in the range 1 32 so only PX1 is specified Option 1 sets the lowest order bit bit number zero value of 1 Option 3 sets bit number two value of 4 Option 6 sets bit number 5 value of 32 Group the options into two groups
172. b MU 5 3 DELETE 5 uc dla oe 3 4 DELETE RECORD centuria 19 6 Deleting a record 19 6 Deleting program lines 3 4 Device specification 5 11 A essen v eitis reti 1 6 ENS d uiu Pai d MEE 6 14 9 4 Dimensioned arrays 6 14 9 4 Direct access files 15 4 Direct statements 3 3 9 1 Direct terminal input 10 12 Disk files ze e tete 1 3 15 1 Definition 7 herd RI o ated 15 1 DITOS XY igne ocio es 10 11 DIN cedens ducit pate A Ed aspi ded 7 2 DIVIDE BY susana ERR s 9 5 DO WHILE UNTILLOOP 9 5 DS WOM is st au REDE t eed 10 11 Duplicate line numbers 4 3 ECHO D MT 9 6 Edit number os doe Sot 8 te te urs 9 24 EDS BEES bs Baek ee Give Re RS 10 5 Editing a string value 10 5 Editing lines in interactive mode 3 4 Editing mask sae 12 1 yer o ts coreeni reaa an s C 1 ELSE s dto dase puel bat cade s 9 6 9 12 END ett ake dd 9 6 16 9 END FILE pudes ex De veas ers 19 3 End of file s scc ced das M dae 15 10 ENDSWITCH fev deg weds Ee e a 9 6 Erg dl cose 2G e d E 3 ENYA treed nx od bee eels E 3 END aries ida E 3 BORA asada nidad Ped 15 10 A P 7 2 Erasing disk files 11 5 15 14 A i E OPEN es 22 6 ERR D cre cec cie is ds 17 2 PAR aae euch iue VEL RENE ES 17 2 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS
173. bad bitmap Break at line n The program reached the breakpoint set at line n 2 C definition is invalid Use C lt name gt lt value gt You attempted to define a constant to the compiler on the command line but the syntax is wrong Check Section 5 3 for the correct syntax Cannot change option some code already compiled You issued a PRAGMA too far down in the source code Some PRAGMAs must appear at the top of the file before any object code has been output by the compiler Move the PRAGMA to the top of the file and check section 5 4 for more details Cannot find program name Check your spelling and or check the directory to see if the file exists Make sure the program specified is in the proper account AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 3 Cannot have DIM within a function definition You placed a DIM statement within a user function definition This is illegal as it will produce a memory leak and a runtime error 30 Redimensioned Array if the user defined function is executed more than once 2Cannot load ISAMP SYS See your System Operator about locating the ISAMP SYS file Cannot open input file Make sure the file exists and you have access to it and try again 2Cannot open output file Make sure the file exists and you have access to it and try again Cannot pass single value to subprogram array You have tried to pass a non array variable as a parameter to a subprogram wher
174. bers Program headers subroutines Program Wall 2 42 rp xeu Prompt symbol Random files Random mode Random Forced mode RANDOM mode Random numbers RANDOM FORCED mode RANDOMIZE Range checking Rawdata RDBMS 00005 Re entrant code READ 4 2 cote ov ade Doa READ ONLY 0 READ READ ONLY Readability of source programs READL er ees READY eta a Record size ooooooo Record number variable Register Parameters RELEASE ALL RELEASE RECORD REM s seed east s RENAME 0 iuris REPEA Dura Page Index 14 Pee a doy 21 1 eee 1 3 7 15 17 AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS User s Guide Index Page Index 15 RESTORE boxe LRL UE RIAM 9 25 9 27 RESUME cusco 9 20 9 27 17 3 to 17 4 22 8 RETURN 5 an arera e Es 9 9 9 27 Revision level ooo oooooomo oo 9 24 Revision subscript 9 24 RIGHT A X carcasas atte Ge eae ed 10 9 Right relative position 8 2 FNDUXS 259 2 Leica care 9 24 10 3 BINDBIOS cas Coto cmt la a a da exe 10 4 FROUNGING es xe esq n eap ER RE 10 4 RTN instruction seu pr bob IE echoes E 2 RUN e ns 3 8 22 8 Run time package 1 3 1 5 5 3 Running
175. ble name For example READ 1 PATIENT INFO WRITE 3 NAME HOLD IT PATIENT INFO Unformatted data at the MAP1 level can have a maximum size of 65 535 bytes 14 2 3 2String Data If the string contained within a string variable is less than the allocated size it is terminated by a null character If you move a string into a shorter variable any characters in excess of the length of the new variable are truncated String variables default to a length of 0 and can have a maximum size of 65 535 bytes AlphaBASIC PLUS User s Manual Rev 02 Page 14 6 Chapter Fourteen 14 2 3 3Floating Point Data Floating point numbers default to the AMOS standard of 6 bytes long You may also specify either 4 or 8 bytes which are IEEE format two word and four word floating point variables Any other specification is illegal 14 2 3 4Binary Data Binary variables may range in size from 1 to 5 bytes Binary data is handy for the storage of small integers or bit flags All numbers are stored as two s complement values Since AlphaBASIC PLUS converts all binary variables to floating point format before performing any arithmetic calculations binary arithmetic is actually slower than normal floating point arithmetic Please note the use of binary numeric variables is not allowed in some instances FOR NEXT loops may not use a binary variable as the control variable although they may be used in the expressions
176. bles called arguments that you wish to pass over to the subprogram The formal parameters define the format type and order of the arguments The first argument in the SUBCALL statement corresponas to the first formal parameter the second argument to the second formal parameter and so on If the number of arguments in a SUBCALL exceeds the number of formal parameters you get an error However if the number of arguments passed is less than the number of formal parameters the remaining formal parameters will have null values Arguments can be passed in two ways 1By value If you pass an argument by value and then change the value of the corresponding parameter variable in the subprogram the calling program will not see the change after the subprogram has finished A copy of the argument is made and the subprogram will operate on the copy On return to the calling program the copy is deleted leaving the unchanged version for the calling program to use 2By reference If you pass an argument by reference any change you make to the value of the corresponding parameter variable in the subprogram will be visible to the calling program on return from the subprogram Expressions are always passed by value Entire arrays can only be passed by reference but individual elements can be passed by value You specify which argument passing method you want on an argument by argument basis for each SUBCALL statement To specify passing by refer
177. broutine by using the RETURN statement for AlphaBASIC PLUS User s Manual Rev 02 Page 9 12 Chapter Nine 9 18GOTO E The format is GOTO label or line number or GO TO label or line number The GOTO statement transfers execution of the program to a new program line This program line must be identified either by a line number or a label somewhere in the program You may use GOTOs to transfer control to a program line either before or after the program line containing the GOTO statement itself For example Program to demonstrate use of GOTOs PRINT This program computes your account balance Use PRINT C to stop enter deposits as negative amounts INPUT Enter old account balance BALANCE CALCULATE BALANCE PRINT INPUT Enter debit amount DEBIT BALANCE BALANCE DEBIT PRINT Your debit was DEBIT PRINT Your current balance is BALANCE GOTO CALCULATE BALANCE You can see there is an endless loop in which control is eternally transferred between GOTO CALCULATE BALANCE and CALCULATE BALANCE The program above runs until you press c8 J C If you use GOTOs on a multi statement line remember to place it last on the line any statements after the GOTO are never executed For example NET GROSS DEDUCTION GOTO GET TAX PRINT DEDUC
178. by a number specifies an octal value NE 9 a tab character in 10 a linefeed character rAr O S 13 a carriage return character rfp 12 a formfeed character CND e c peu a delete character eu 39 an apostrophe NN 92 a backslash character itself Character constants are useful for clarifying code in many cases For an example it is clearer to write FOR I a TO z than FOR I 97 to 122 Note that the character constants are true integers Therefore you cannot set up a string containing carriage return and line feed by using READY 10 AS Nr An 20 PRINT AS RUN 1310 The mixing of data types within the same expression are outlined in a later section 6 2 4 2Alterative Radix Constants Alternative radix constants can also define true integer constants As with character constants they can often clarify your intentions in your source code Only the compiler understands these symbols so they cannot be used with DATA or INPUT statements COMPLP understands the following alternative radix prefixes which can be in either case amp h hexadecimal format amp O Octal format amp b Binary format amp r RAD50 format three characters only The prefixes are placed immediately before the value they are acting upon with no intervening spaces For example EXTENSIONS amp rRP FLAGS h01 OR FLAG AlphaBASIC PLUS User s Manual Rev 02 Page 6 12 Chapter Six The AMOS M
179. c 10 8 8 Backspace Cc 11 9 9 Character Tabulation Cc Tab 12 10 A Line Feed Cc 13 11 B Line Tabulation Vertical Cc Tab 14 12 C Form Feed Cc 15 13 D Carriage Return Cc 16 14 E Shift Out Cc 17 15 F Shift In Cc 20 16 10 Data Link Escape Cc 21 17 11 Device Control One Cc AlphaBASIC PLUS User s Manual Rev 02 Character Sets Char Also IS4 IS3 IS2 IS1 OANODOOaARWN O TOTMOOD gt O vo lA Octal Called Value 110 Decimal Value Hex Value ISO IEC 10646 1 1993 E and Unicode 2 0 Name Space Exclamation Mark Quotation Mark Number Sign Dollar Sign Percent Sign Ampersand Apostrophe Left Parenthesis Right Parenthesis Asterisk Plus Sign Comma Hyphen Minus Full Stop Solidus Digit Zero Digit One Digit Two Digit Three Digit Four Digit Five Digit Six Digit Seven Digit Eight Digit Nine Colon Semicolon Less Than Sign Equals Sign Greater Than Sign Question Mark Commercial At Latin Capital Letter A Latin Capital Letter B Latin Capital Letter C Latin Capital Letter D Latin Capital Letter E Latin Capital Letter F Latin Capital Letter G Latin Capital Letter H AlphaBASIC PLUS User s Manual Rev 02 Also Known As Device Control Two Device Control Three Device Control Four Negative Acknowledge Synchronous Idle End of Transmission Block Cancel End of Medium Substitute Escape File Separator Group Separator Record Separator Unit Separator Hash A
180. cem tct dt senis ede aar 9 31 9 53 WHILE caches e eite un PAIN RULES 9 31 S IL e AN dos A eet OE 9 31 CHAPTER 10 FUNCTIONS 10 1 NUMERIC FUNCTIONS sss ccoo 10 2 RE SE A daba sai regit A 10 2 TODO A ist nak cats on trae bac eer eo 10 2 A EX PIG A O actione de i R 10 2 TOR AS EAGT OO iret A nett mentee ead teed 10 2 TOA SPIN A CI E E 10 3 TOE IN A A Ir EI 10 3 iowa rae tercio A CR A et IER 10 3 AR 0 eso ng hk TO 10 3 LOLI FINDING a cans nate aide A O ae 10 3 10 3 1 ON A gee a wads eR mE 10 4 ASNO ads REO Sis Ne Mare LOTE fash daa 10 4 TOA AD SOR nouem as ee eoe AOL pe DERENG A ae 10 4 TOTAS VAN m cs a ccoucencg um mu rta I EUR MEER cue ds 10 4 10 2 TRIGONOMETRIC FUNCTIONS ss sss ee 10 4 10 3 STRING FUNCTIONS o5 2 ceni E ei 10 5 15 350 OUR OG eros aval nin ni ate ate ace e de eu RO 10 5 o A cr ombra ee Lima d 10 5 E Rn Rone Mas Lad ete ht eU A 10 6 AlphaBASIC PLUS User s Manual Rev 04 Table of Contents Page v 10 4 OSA INSTA AS BI A tr aoro dietd 10 6 ipa DOSCASI A A redo Eta Ys 10 7 JU dB LERTAS Dues rE cete iste beet eed eit 10 7 10 3 2 PENAS A A O 10 8 10 3 8 MIDI sce chee et o A ea eee OA aa EA 10 8 10 39 BIGHT AS aia ERA 10 9 10310 SPACE eu e esse rice PCS 10 9 10 3 LI S TBOO o e uctor reae IA 10 10 10 322 STRIPSIAG 202 cet E DU HER 10 10 TLE SCH TIME LOC decenter nO Pe pee el 10 10 10314 UCSIA at ossoecei nte pi ve diit C vb TEN E apte 10 10 MISCELLANEOUS FUNCTIONS isss ee 10 11 TOA O
181. creen Display Turn On Screen Display Top Left Corner Top Right Corner Bottom Left Corner Bottom Right Corner Top Intersect Right Intersect Left Intersect Bottom Intersect Horizontal Line Vertical Line Intersection Solid Block Slant Block Cross Hatch Block Double Line Horizontal Double Line Vertical Send Message to Function Key Line Send Message to Shifted Function Key Line Set Normal Display Format Set Horizontal Split Follow with Row Code Set Vertical Split 39 Character Columns Set Vertical Split 40 Character Columns Set Vertical Split Column to Next Character Activate Split Segment 0 Activate Split Segment 1 Send Message to Host Message Field Up Arrow Down Arrow Raised Dot End of Line Marker Horizontal Tab Symbol Paragraph AlphaBASIC PLUS User s Manual Rev 02 Screen Handling Codes TCRT CODE 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 106 107 108 109 110 111 112 113 114 115 Page D 3 FUNCTION Dagger Section Cent Sign One Quarter One Half Degree Trademark Copyright Registered Print screen Set to wide 132 column mode Set to normal 80 column mode Enter transparent print mode Exit transparent print mode Begin writing to alternate page End writing to alternate page Toggle page Copy to alternate page Insert column Delete column Block fill with attribute Block fill with character Draw a box Scroll box up one line Scr
182. ctions are implemented in full accuracy SIN X Sine of X COS X Cosine of X TAN X Tangent of X ATN X Arctangent of X ASN X Arcsine of X ACS X Arccosine of X DATN X Y Double arctangent of X Y AlphaBASIC PLUS User s Manual Rev 03 Functions Page 10 5 The arguments X and Y are assumed to be in radians For computations on arguments in degrees multiply the argument by pi divided by 180 For example PRINT TAN 20 3 1415926 180 ETA 25629 10 3STRING FUNCTIONS The following string functions accept numeric or string arguments and perform operations on strings You may specify these functions with a after the name for clarity if you wish i e CHR 90 or CHR 90 10 3 1CHR X Returns a single character having the ASCII decimal value of X Only one character is generated for each CHR function call For example READY PRINT CHR 90 Z X should be in the range from O to 255 inclusive Values outside this range may produce strange result 10 3 2EDIT A C The format is EDITS expression edit code EDIT modifies the expression according to the edit code Numeric expressions are converted to string The codes are Take out all spaces and tabs Take out excess characters CR LF FF ESC RUBOUT amp NULLs Take out leading spaces and tabs 6 Reduce spaces and tabs to one space 2 Take out trailing spaces and tabs ot off DP You may combine these editing options by specifying an addi
183. ctor IF Factor Last 1 THEN PRINT I NEXT 1 In the above case EXIT transfers control to IF Factor Last 1 THEN PRINT Iifthe IF A lt 0 statement tests TRUE Using EXIT lets you test conditions other than those tested in the loop control variables themselves It also lets you have a test in the middle of the loop instead of at the beginning or end 9 16FOR TO NEXT AND STEP The format is FOR control variable expr TO expr STEP expr statements NEXT control variable The FOR and NEXT statements initialize and control program loops A loop is a structure in which the same statement or statements can be performed a specific number of times Whether or not a loop is executed depends upon the value of the control variable The control variable may even be subscripted It can be either a six byte or an eight byte floating point variable a 4 byte integer or a single alphabetic string character such as a The delimiters expr may be any valid expression FOR initializes the control variable to the first expression NEXT increments or decrements the value of the control variable each subsequent loop There must be one and only one NEXT statement for every FOR statement and the NEXT statement cannot be part of an IF THEN ELSE or SWITCH expression or included in a GOSUB or subprogram that doesn t have the FOR st
184. d Illegal record size Block allocate deallocate error Miscellaneous error Memory map destroyed Insufficient privileges to run program Must be logged into 1 2 Must be logged into DSKO 1 2 Program requires 68020 processor Must be logged in to run program Bus error Memory parity error Address error Illegal instruction Divide by zero error CHK instruction trap TRAPV instruction trap Privilege violation Trace trap return EM1111 instruction trap Miscellaneous exceptions Illegal interrupt on level 0 Illegal interrupt on level 1 Illegal interrupt on level 2 Illegal interrupt on level 3 Illegal interrupt on level 4 Illegal interrupt on level 5 Illegal interrupt on level 6 Illegal interrupt on level 7 Bus time out error MMU error AlphaBASIC PLUS User s Manual Rev 02 ERR 3 Error Codes ERROR CODE 284 285 286 287 288 289 290 291 292 293 294 384 385 386 387 388 389 390 512 513 514 515 516 Page G 3 ERROR Co processor protocol violation FPCP branch or set on unordered condition FPCP inexact result FPCP divide by zero FPCP underflow FPCP operand error FPCP overflow FPCP signaling NAN MMU co figuration error MMU illegal operation MMU access level violation Language processor aborted Language processor aborted with errors Language processor completed with errors Undefined identifier in input Runtime interpreter error Syntax error in input Assembly error in linkage
185. d 11 1 LOOKUP 2d toe ec eie A ees 11 4 15 15 LO0D Eacngeciee ee brem teta tmd be 9 5 9 7 AlphaBASIC PLUS User s Manual Rev 02 Page Index 11 AlphaBASIC PLUS User s Guide Index Loop delimiters o 9 7 Major revision NUMber 9 24 Making programs more efficient C 1 Managing Memory C 1 MAP S as eot een Oe Sen ene ive BS Gee a 14 9 Dive ade sacs ete ee wie tee ae oe ee ed 14 2 EXaMpleS cio ia 14 9 Corel A e a a e a Mes 14 3 OFIGIIT 2s a Barter ccowinrt duende dd 14 2 14 7 DIZE oct Iib siu out bara s 14 2 14 6 Statement format 14 2 TO esten avers ees EQUES 14 2 14 5 ValUG 4 cuneta bere der dus 14 2 14 6 Variable name ssue 14 4 MAP statement format 14 2 Matching strings ar hes 10 6 Mathematical expressions 7 1 Mathematical operators 7 1 AND a oss dre Mos ivi SS ced stt 7 2 DIN Lam aed eo BOs eect aen ett di to doe 7 2 EQV ala ER E o fn 7 2 FMOD a casona e 7 2 MAX sos ba bowed tal 7 2 MIN ig aoe car eee Geese 7 2 MOD sites cremate sana anes eter Pa des 7 2 NOT Re mer Cae SR NE Meine Sea 7 2 s esheets bs ee Sane pee eee Be 7 2 WING A ok eau aa eaten ees 7 2 XOR ira dU epe pene eee 7 2 fir M a oes ik Nene OO tee Oe EA 7 2 Maximum line length 2 4 5 2 MEM AN 207s Bah Eder NP RODEO 11 3 WAIUCS sh tion ta ay Peat ye 11 3 MEMORY erstes ais 2 4 Allocation vv
186. d as an positional bit in an unsigned value For example SIGNIFICANCE 11 MAP 1F f 6 1 9 MAP 1B b 4 B F B 4294967294 The floating point value 1 9 is converted to an integer value 2 The two s complement bit pattern representing 2 11111 110 is placed in B The unsigned value of that bit pattern is B s value 9lf strings and numeric variables an or constants are used in the same expression AlphaBASIC PLUS will convert one type to another automatically according to the rules for mixed type expressions described in the next section AlphaBASIC PLUS User s Manual Rev 02 Page 7 6 Chapter Seven 7 6MIXED TYPE RULES Expressions may contain any mixture of variable types and constants in any arrangement AlphaBASIC PLUS performs string and numeric conversions as necessary to make sure the result is in the proper format For example if two strings are multiplied together they are first converted to numeric format before the multiplication takes place If the result is then to become a string it is reconverted back to string format before the assignment is performed In other words the statement AS BS 345 is perfectly legal and works correctly as long as B contains a number and no alphabetic characters This is a powerful feature which can save programming effort when used correctly There is a seemingly ambiguous situation which arises from this mode independence The plus symbol is used both
187. d the floating point multiplication could be 20065 999987 When that is converted to an integer by truncation of the decimal fraction the result is the unexpected and unwanted 20065 The programmer must defend against the possible loss of precision rounding error inherent in floating point arithmetic by modifying the program to MAP 1 FPT F 6 MAP 1 INT VALUE I 4 INPUT Enter monetary value FPT INT VALUE FPT 100 0 005 or MAP 1 FPT F 6 MAP 1 INT VALUE I 4 INPUT Enter monetary value FPT INT VALUE RNDN FPT 100 AlphaBASIC PLUS User s Manual Rev 02 Variables Page 6 9 The extra term added is one half of the smallest decimal fraction that can be entered This would bump the intermediate result to 20066 444487 which correctly converts to 20066 The RNDN function achieves the same result This is just a very brief overview on floating point arithmetic Many books and papers have been written about floating point arithmetic and ways to reduce loss of precision and accuracy and you are recommended to read one for further details 6 2 2String Variables A string is any character or group of consecutive characters Strings can be from zero to 65 535 characters in length The characters can be letters numbers typographical symbols non printing symbols or any other character from the system s character set Each character is stored in one byte in th
188. d to adjust the size of this area The following PRAGMA setting affect the size of this area PRAGMA ADD EXTRA STRWRK constant expression PRAGMA EXTRA STRWRK constant expression PRAGMA SET STRWRK constant expression constant expression is a compile time expression that follows the same rules as values for a DEFINEd constant The values must be between 2MB and 2MB See Appendix for a discussion on the string work area and its required size AlphaBASIC PLUS User s Manual Rev 03 Writing Program Files Page 5 11 5 5RUNNING A PROGRAM d Enter RUNP and the name of the program you want to execute For example RUNP LOOP Sum You can also pass command line arguments to your program See the CMDLIN statement in Chapter 10 You may enter a full file specification including device name and account number The monitor looks for the run time package RUNP LIT in memory if it isn t found in system or user memory it loads RUNP into memory from the disk RUNP prepares an area in memory for your program to use then searches for your program in memory If it is not there RUNP loads the specified RP file from the disk Then RUNP executes your program Upon completion or if you press cR J Ec to stop the program RUNP returns you to monitor level After making changes to your program you must re compile it prior to using RUNP or you will run the old version of the program 5 5 1Runtime Options The runtime system has on
189. d to numeric 34 and multiplied by the 5 The plus sign then performs numeric addition instead of concatenation The result is in numeric format Here are a few examples AlphaBASIC PLUS User s Manual Rev 02 Expressions and Evaluation Page 7 7 EXAMPLE RESULT EXAMPLE RESULT A 23445 A 23445 B 34 5 B 34 5 C 34 5 C 34 5 D 34 p D EE 34 5 You can see conversion is affected by the type of variable being used You might like to try a few examples of your own on your system to see what the results are Any potentially ambiguous expression may always be forced to one type or the other by use of the STR X and VAL A functions see Chapter 10 For more examples of mode independence see the sample programs in Chapter 8 7 7DIVISION AND MODULUS OPERATIONS AlphaBASIC PLUS differentiates between integer and real operations and results for two operations the division and modulus remainder operations Division can be done in two ways either as converting each operand to integers and producing an integer result or converting each operand to floating point and producing a floating point result The former is specified by the DIV operator and the latter by the operator The two modulus operators operate in a similar way the integer version is MOD and the floating point version is FMOD Correct use of these operators is essential for accurate calculations For example 1 I I 4 14 5 14 5 H I
190. depo pea 22 5 VARIABLE 222 a ete ed 22 9 Debugger 0 02 bs ew bs Poe toe n oh 22 1 Command mode 05 22 3 Key sequences 2 000 22 2 Screen mode iia ga descend a 22 3 Debugger commands s haa ind deca aisha ly PANINI ba E A iecit td 22 4 MEE RET T IT 22 4 AMOS cendres ete Td 22 5 ATA S irre ime a RE ie 22 6 BREAK sore de ble wet ta IT RETE 22 4 CRAINS A See eT 22 9 CHANNEL stored a dio Poem de dde 22 6 RIGA su iL ou deg E as 22 4 ERR ceed otterrai tSt e AERE ES 22 6 FILE osease dart PRESA et 22 6 FUNCTION 4 3 te Rer 22 7 INDENT 45 oh Pec m 22 7 LABEL caesis REN Atte AS AR 22 7 LET asutuii dass pi ett beet es 22 7 NEW e raras DRIED 22 8 PROC EE Debut duda itr eta oS 22 8 QUIE rca a DEDERIT UNE 22 8 REMOVE used nia rabia 22 8 RESUME si o 22 8 RUN rt SD a ege a 22 8 SCALE aiie at anata SY os Goes Bee Cece gs 22 8 SEARCH vaca tak cd deme gee ds 22 5 SIGNIFICANCE 2 ar stat oe agar a 22 8 SUBPROGRAM ceca 22 9 TRAGE e eat si n aa E t 22 9 Ripe 22 5 UNTRACE oro bR isRLEIOS RETE UAR 22 9 AlphaBASIC PLUS User s Manual Rev 02 Page Index 5 AlphaBASIC PLUS User s Guide Index Page Index 6 UNTHRAP uscar 22 5 VARIABLE 5 ates caros 22 9 Debugging MAP statements 14 13 Decimal Logarithm 10 3 Decimal values F 1 DERFEN rotaci n ERE ERE bt 20 1 DEFINE sii as rte taeda ars subiere 9 3 Defined function examples 20 5 DEL 0 ehm eda qu
191. description techniques Pascal record definitions and C structures Why should you use mapped variables Well mapped variables offer the following advantages eThey can save memory eThey make variables easier to refer to eThey can make it easier to access data in random data files eThey can improve the logic and readability of your program If all variables are mapped at the start of the program it is easy to see what variables are used and how they are related Defining all variables used is good programming practice eThey let you define binary variables which can save memory when using flags AlphaBASIC PLUS User s Manual Rev 02 Page 14 2 Chapter Fourteen Let s take a look at an example to show you how mapped variables can help you Say you want to write a program that keeps a record for each of your employees You want to know the employee s name social security number employee number and rate of pay In most cases where you are dealing with the variable containing the employee s name you also want to work with one or more of the other variables too Using regular AlphaBASIC PLUS variables you might have EMPL NAME SOC SEC NUM EMPL NUM and PAY RATE If you want to read one employee s records in from a file you need a statement like this READ 1 EMPL NAMES SOC SEC NUMS EMPL NUM PAY RATES If you use variable mapping however you could set up the variables so they all
192. down while the indicated key is pressed This symbol in front of a capital letter means the letter is a control character For example when you press 8 J C it appears on your screen as C C is the control character that cancels most programs and returns you to AMOS command level This symbol means halt It indicates an important note you should read carefully before going further in the documentation Usually text next to this symbol contains instructions for something you MUST or MUST NOT do so read it carefully This symbol means hint It indicates a helpful bit of information or a short cut that could save you time or trouble This symbol means remember It indicates something you should keep in mind while you are following a set of instructions AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 2 GENERAL INFORMATION This chapter gives general information about the form your AlphaBASIC PLUS programs may take We discuss eLines with more than one BASIC statement eStatements using more than one line eNumbering lines eHow to put comments in your programs eUsing labels in programs eHow AlphaBASIC PLUS gives programs memory eReserved word spacing eThe case of letters in programs eAlphaBASIC PLUS libraries 2 1LINE NUMBERS E Program line numbers may range from 1 to 65535 Programs used in interactive mode MUST contain line numbers Programs to be compiled at AMOS level do not require line number
193. ds to be filled by multiple expressions If you supply more expressions than the format string is meant to handle AlphaBASIC PLUS re uses the format string until each of the elements in the expression list has been formatted If you supply fewer expressions than the format string is meant to handle AlphaBASIC PLUS ignores the unused portion of the format string AlphaBASIC PLUS User s Manual Rev 02 Formatting Output Page 12 3 You may also send formatted data to a file by specifying a file channel number after the PRINT keyword For example PRINT 1 USING format string expression list For information on sending data to files see Chapter 15 12 2HOW TO SPECIFY FORMAT STRINGS The sections below discuss the special characters that make up a format string and control the output of your data Characters other than these special formatting characters which appear in a format string are output literally as part of your data 12 2 1Formatting a Numeric Field The symbol in a format string always indicates you want to format numeric data Each symbol in a format string represents one numeric digit The simplest numeric format string consists of just symbols For example PRINT C USING The statement above tells AlphaBASIC PLUS to format the numeric variable C into a field of four digits with no fractional part If the format string causes AlphaBASIC PLUS to remove the fractional part of a number AlphaBASIC P
194. e If X 0 GETKEY doesn t wait for input and returns a 1 if there are no characters in the input buffer If X 1 GETKEY waits until a character is entered at the keyboard If X 2 GETKEY checks to see if there is input waiting If there are not any characters in the input buffer GETKEY will immediately return 1 If there is a character waiting GETKEY will return its ASCII decimal value but the character is not processed Successive GETKEY 2 will return the same value until the character is read with a GETKEY 0 or GETKEY 1 statement or another INPUT GETKEY returns the ASCII decimal value of the character You can use CHR to translate the ASCII code to the corresponding character Values for X other than O 1 and 2 are reserved for future use and produce undefined results Here is an example AlphaBASIC PLUS User s Manual Rev 03 Functions Page 10 13 User Input CHR GETKEY 1 IF User Input A THEN The optional translation table filename specifies a memory module either in user or system memory to be used as a translation table for the input characters This table can translate any character into one or more other characters It can be used to translate the character generated by special keys such as function keys into specific instructions For example you might want your program to display information when the HELP key is pressed If you specify only an extension
195. e subroutine Program headers are defined by using the PHDR macro discussed in your AMOS Monitor Calls Manual AlphaBASIC PLUS User s Manual Rev 02 APPENDIX F CHARACTER SETS AMOS uses a single byte character set Such a character set can represent 256 different characters The character set is aligned with a number of international standards F 1 ASHORT HISTORY OF CHARACTER SETS The first international standard was set in 1965 by ECMA European Computer Manufacturer s Association and was known as ECMA 6 The character set was adopted by other standards bodies and is also known as US ASCII DIN 66003 and ISO 646 The standard only defined a basic alphabet and did not allow for national characters in use in many European countries Such characters were incorporated by specifying twelve code points see Note 1 in the table below as being places where replacement characters could be defined For example Germany defined the letter A at code point 91 where the character was located These character sets were called the national ISO 646 variants Portability of files containing such characters were low In 1981 the IBM PC introduced an 8 bit character set with Code Page 437 a character set with many special characters In 1982 DEC MCS Multi Language Character Set was released This character set was very similar to ISO 6937 2 which in turn is almost identical to the modern standard for 8 bit character sets ISO 8859 In 1985 E
196. e the line LOKSER queue is full A system resource the LOKSER queue is full Contact your System Administrator and request the LOKSER queue be expanded LOOP without DO Add a DO statement to make a complete loop AlphaBASIC PLUS User s Manual Rev 02 Page A 14 Appendix A MAP 1 S or X type max size of 64k exceeded A MAP 1 variable cannot be greater than 65 535 bytes in size Adjust your MAP statements to fulfill this condition Mismatched FOR variable The variable you used in FOR isn t the same type as what you are comparing it to Change the statement so the variables have the same type Missing colon after C switch You tried to specify a constant on COMPLP s command line but did not put a colon after the C and before the constant s name Try again with the colon inserted Missing colon after P switch You tried to specify a constant on COMPLP s command line but did not put a colon after the P and PX switches and before the constant s name Try again with the colon inserted Missing comma in P switch You tried to list on or more options for a P switch but left out a comma between option numbers Missing statement type statement text line Check the format of the statement and try again Multiple PROGRAM statements Only one PROGRAM statement is allowed per program Remove any extra PROGRAM statements Multiply defined function You defined the same function twice Change or remove one o
197. e value of the main variable is saved until the function is done and then restored This could cause a problem in a program if you re not careful For example if you have a variable defined as a string in the main program called HOURS and then define a function like this AlphaBASIC PLUS User s Manual Rev 02 Page 20 4 Chapter Twenty DEF FN Wages HOURS OVERTIME FN Wages HOURS OVERTIME ENDEN You get an unexpected result from the function because the function takes the type for HOURS as string and concatenates the value passed to HOURS and to OVERTIME instead of adding them concatenates strings but adds numbers Thus if you passed the values 3 and 5 to the function the answer would be 35 instead of 8 To avoid this problem use unique local variable and parameter names or MAP them at the start of your program 20 5USING DEFINED FUNCTIONS Functions can be called recursively that is it can call itself within its own definition see the DEF FN fact n example above How deep depends on many factors including what is on the current runtime stack the runtime stack size the number of parameters and local variables used in the function etc The parameters are passed by default in a call by value manner See Appendix H for details on how to adjust memory allocations if you want to execute deeply recursive functions Functions can use all local and global variables but
198. e according to the result of the operation The format is KILL filespec For example if KILL NEW TXT 0 then goto FILE NOT FOUND The filespec is any string expression which evaluates to a legal file description The default extension is DAT Do not try to KILL a file you currently have OPEN This could cause corruption on the disk If you try to KILL a file another program has OPEN you see an error message If you try to delete a protected file you see a Protection violationerror message You may also use KILL as a keyword see Chapter 15 AlphaBASIC PLUS User s Manual Rev 04 Page 11 6 Chapter Eleven 11 8RENAME The RENAME function renames a file on the disk and returns a value according to the result of the operation The format is RENAME filespec new nam For example RESULT RENAME NEW TXT OLD TXT The filespec is any string expression which evaluates to a legal file description The default extension is DAT The function returns a 1 if the file was found and renamed or 0 if it was not found or if it was protected Do not try to RENAME a file you currently have OPEN This could cause corruption on the disk You may also use RENAME as a keyword see Chapter 9 11 9VER The VER function returns a string of the current version number of one of a choice of progams etc The format is string variable VERS code
199. e appropriate system error message is printed After your error recovery procedure is done use RESUME to continue the program execution RESUME line number or label For more information on error trapping see Chapter 17 9 300N GOSUB CALL The ON GOSUB statement allows multi path branching to one of several subroutines within the program based on the result of evaluating an expression The formats are ON expression GOSUB label line 1 label s line s ON expression CALL label line 1 label s line s expression can be any valid expression which is evaluated and truncated or rounded if IEEE to a positive integer result The result of the expression evaluation is then tested The subroutine at label line 1 is executed if the result is 1 the subroutine at Label line 2 is executed if it is 2 etc If the result is zero negative or greater than N the program goes on to the next statement As with GOSUB the verb CALL may be used in place of the verb GOSUB giving an ON CALL statement Here is an animation program using ON and GOSUB START I 3 RND O 1 Random number 1 to 4 ON I GOSUB UP DOWN STRAIGHT Go to 1 of 3 subroutines GOTO START UP PRINT TAB 1 3 RETURN Draw symbol up 1 row DOWN PRINT TAB 1 4 Down 1 row draw RETURN STRAIGHT PRINT 2 Draw symbol RETURN AlphaBASIC PLUS User s Manual Rev 02 Program
200. e channel STATS MAP INDEXED STATS filespec STATS MAP The first syntax causes the file statistics to be received from ISAMP SYS It assumes an ISAM PLUS file has been successfully opened The second syntax causes the file stats to be received from ISMUTL LIT The STATS MAP is a MAP structure to receive the ISAM PLUS file stats See your ISAM PLUS System User s Guide for more information on the STATS MAP variables If the memory area defined by the STATS MAP is insufficiently large to hold the stats information the information is truncated to fit Note it is not an error for STATS MAP to be too small AlphaBASIC PLUS User s Manual Rev 03 Using ISAM PLUS Files Page 19 9 19 6ERROR PROCESSING AlphaBASIC PLUS reports errors from ISAM PLUS and FILSER the AMOS file service system The reporting mechanisms should help you in turn to write routines for handling errors for terminating abnormal conditions or for re trying an operation The ISAM PLUS error codes and status values are listed in your SAM PLUS User s Guide The FILSER error codes are listed in your AMOS Monitor Calls Manual AlphaBASIC PLUS User s Manual Rev 03 CHAPTER 20 USER DEFINABLE FUNCTIONS This chapter explains how to design your own function calls and use them It discusses eThe advantages of defined functions eSingle line functions eMultiple line functions eHow to use defined functions 20 1WHY USE DEFINED FUNCTIONS Defi
201. e computer As a byte consists of 8 bits there is a total of 256 values or unique characters that can be represented If each byte is treated as an unsigned character a character can have a value or code point ranging from zero to 255 inclusive The symbol or glyph associated with each code ppint is locally determined by all the input and output devices used on the system AMOS expects the devices to be consistent i e be set to produce the same glyph for the same code point defaulting to the ISO Latin 1 character set shown in Appendix F ISO Latin 1 is a 256 character set and is a superset of the US ASCII character set which itself consists 128 characters A 128 character national replacement character set may be used instead If the device settings are not consistent printing say a glyph for code point 123 decimal may produce a left brace on one device but a Latin small letter E with an acute accent on another The only code point that cannot be stored in a string is zero the null character as this character is used internally by AlphaBASIC to signal the end of the string Under AlphaBASIC PLUS a string is defined to have a maximum size Either the string fills up that size completely or the string is terminated by a null character and subsequent bytes up to the size of the string are undefined and inaccessible to programs AlphaBASIC PLUS stops processing subsequent bytes after seeing the null character A string vari
202. e eee eee 7 1 7 3 LOGICAL OPERATORS sica A E PSU EIER 7 2 7 4 OPERATOR PRECEDENCE 5c eb tk ER I eR Ra ette 2 7 3 7 5 BULESOFGAEGBEATION 2 5 2 Bae ee SE EET RR REIR 7 4 7 6 MIXED TYPE RULES oa a A 7 6 7 7 DIVISION AND MODULUS OPERATIONS lesser 7 7 7 8 THE SIGNIFICANCE OF SIGNIFICANCE 2 0008 7 8 CHAPTER 8 WORKING WITH STRING VARIABLES 8 1 WHAT IS A SUBSTRING MODIFIER 2 00 008 8 1 8 2 HOW DO YOU USE A SUBSTRING MODIFIER 8 1 8 3 SETTING THE SIZE OF THE STRING WORK AREA 8 4 PART THREE COMMANDS AND FUNCTIONS CHAPTER 9 PROGRAM STATEMENTS 9 1 AMOS in a a 9 1 DA NGALL A O 9 2 9 3 CASE ms 9 2 9 4 CHAIN tc a a Dh teer hi ceris E a ei eco 9 2 9 5 DATA qos dla A al A EA 9 3 9 5 DEFAULT aa ex eph dete ed A da pad 9 3 Sr DEFINE tn eoe Seed eaa d sie eR qx A en ta Ei 9 3 9 8 DIM rS 9 4 9 9 BINIBE BY Osce Ex O AREAS AAA 9 5 9 10 DO WHILE UNTIL LOOP 4 eek eR RERO REIR eed Reed 9 5 911 ECHO riene o e da 9 6 9 12 ELSE a eA Ain ete EA n EA 9 6 dls END dae pio ata poco da de 9 6 9 14 ENDSWITGH lt 5 ran nari n eOk Sea EUR EN ERR 9 6 9 TO A E E OTR EN PU ATER 9 7 9 16 FOR TO NEXT AND STEP tact et hag ette ate eR eto 9 7 9 17 GOSUB OR CALL AND RETURN 2 00008 9 9 9 18 aO TO e Seco edo ovs loqui unde EUREN E REESE tu E NA 9 12 9 19 1 THEN AND EESE wo id bo hag eed o REA 9 12 9 20 INT zd emet oe ERU et dae soie A ERE CERE
203. e in the subprogram that parameter is defined as an array Cannot run RP with DIM statements from RES or MEM RP or SPG files produced by early versions of COMPLP did not allow you to load them into system or user memory if they contained DIM statements Later versions of RUNP detect such RP or SPG files if they are loaded into system or user memory and produce this runtime error Recompile the source file under COMPLP verison 1 0 26 or later and execute it under RUNP version 1 0 267 or later 2Cannot use CHAIN in a function You put a CHAIN statement within a user defined function This will produce a memory leak and is forbidden You must return out of all subprograms or user defined functions via ENDFN statements to the main program and CHAIN from there Cannot use CHAIN in a subprogram You put a CHAIN statement within a subprogram This will produce a memory leak and is forbidden You must return out of all subprograms via SUBEND statements to the main program and CHAIN from there Can t assign a value to a constant Use a variable AlphaBASIC PLUS User s Manual Rev 02 Page A 4 Appendix A Can t resolve constant in IF A constant in the IF line hasnot been DEFINEd or passed as a command line constant definition You must DEFINE such a constant before the IF statement Can t continue You have attempted to continue a program which is not stopped at a breakpoint or which has reached a point where it can go n
204. e is considered and a port number expression greater than 511 causes BASIC to ignore the unused bits The range of ports available is O to 511 IO X expr Writes low byte of expr to port X A 10 X Reads decimal port X into A If X is 0 255 the function accesses the external I O ports the addresses are FFFFFFOO FFFFFFFF If X is 256 511 it accesses the internal on board I O ports addresses FFFFFEOO FFFFFEFF The user must have read system memory privileges to use the lO x function or he she will receive a protection violation error 11 4MEM X Returns a positive integer value which specifies the decimal number of bytes currently in use for various memory areas used by the compiler system The most common use of MEM X is to return the number of free bytes left in the user memory partition The MEM 0 call duplicates the action performed by the FRE X function in some other versions of BASIC Other values of the argument X return memory allocations which pertain to various areas in use by the compiler and may or may not be of use to you The byte counts returned for the various values of X are 0 Free memory space remaining in current user partition 1 Total size of current user partition 2 Size of source code text area 3 Size of user label tree 4 Size of user symbol tree variable function names 5 Size of compiled object code area 6 Size of data pool compiled DATA statements 7 Size of array index area dynamic
205. e n is a number from 1 to 16 FIXED or DYNAMIC FIXED variables are not defined by a MAP statement and are allocated automatically when the compiler finds references to them in the program DYNAMIC variable arrays are allocated by a DIM statement or by a default reference to a subscripted variable If the array is dynamic and has not been allocated yet the subscript values are replaced by the letter X to indicate they are not known at this point Remember any variable defined in a MAP statement which is in a lower level relative to another variable inherits all subscripts from that higher level variable The size of the variable is given in decimal bytes In the case of arrays the size represents the size of each single element within the array The location of the variable is a little tricky to explain since it is actually an offset to the base of a storage area set aside for the allocation of user variables AlphaBASIC PLUS User s Manual Rev 02 Page 14 14 Chapter Fourteen As each new variable or array is allocated it is assigned a location which is relative to the base of this storage area The location information given here is an example to help you understand the relative placement of the variables in the mapping system and does not represent the actual memory locations which they occupy There are two distinct areas in use for variables and thus the offsets of the variables are to one of these two areas All FIXED and MAP
206. e optional switch controlling its operation R You can use R in two ways First it can display features and available options of RUNP To do this type RUNP R en Second you can use R to display features and required option features set by a COMPLP P switch or PRAGMA FEATURE list of an object file To do this type RUNP R filename filename is the name of the object file you want information about Do not place the R after the filename or else RUNP will execute the file with a command line of R AlphaBASIC PLUS User s Manual Rev 03 CHAPTER 6 VARIABLES This chapter discusses the following topics Variable Names eL abel Names eUser Defined Function Names eExternal Assembly Language Subroutine XCALL Names eSubprogram Names eNumeric Variables el EEE Variables eString Variables eArray Variables 6 1NAMES Names in AlphaBASIC PLUS crop up in many places Variables and labels user defined function names XCALL subroutine names and so on This chapter defines rules for the formation of valid names 6 1 1Variable Label and User Defined Function Names These names obey a common set of rules in addition to some specific rules for their type The common set of rules is that the name eMust start with an alphabetic character AlphaBASIC PLUS User s Manual Rev 02 Page 6 2 Chapter Six eCan contain alphanumeric characters plus apostrophes and underscores both of which are significant in the name el
207. e syntax of your file specification Make sure the correct disk and account have been given Program name You tried to SAVE or LOAD a program without providing a filename Enter the filename at this point Protection violation Your program tried to write into another account where you do not have write privileges Write to a different account or talk to your System Operator about getting access to the account you want Record in use The random file record your program wants to access is already locked by another user Only for File Locking systems You may want to specify WAIT RECORD in your file access statement Record not locked Your program tried to update a random file record it had not first locked with a READL instruction Only for File Locking systems AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 17 Record size overflow Your program tried to read a file record into a variable larger than the file record size Re adjust your variable size or your record size Redimensioned array You tried to redimension an array An array can only be dimensioned once in any one AlphaBASIC PLUS program Remove any extra DIM statements for that array and prevent each DIM statement from being executed more than once Relational operator expected Adjust your code so the expected condition is fulfilled Remote not responding Your program tried to access a file on a remote system and that system was not open for acc
208. eWhenever possible group code into sections by using subprograms functions and subroutines Your program then becomes a series of sub programs each accomplishing a task Organizing your program in this manner also makes it easier to design and write your program eUse tabs or regular spacing to indent sections of program code so a reader can see the structure For example FOR I 1 TO 10 FOR J 1 TO 20 K J 1 NEXT J K 14 J NEXT I eDon t use more than one statement per line eUse comments to explain lines that may be unclear and especially to explain what each routine subprogram function etc do eUse blank lines and comments to visually set off independent sections of code subroutines functions loops etc eEstablish programming standards within your group or company so all programs follow the same conventions AlphaBASIC PLUS User s Manual Rev 02 APPENDIX D SCREEN HANDLING CODES Below is a list of the terminal handling codes TCRT codes established at the time of the printing of this manual For the most up to date list see your AMOS Terminal System Programmer s Manual Chapter 12 explains how these codes can be used by AlphaBASIC PLUS programs All TCRT codes are reserved for future expansion by Alpha Micro If you have a specific need for a new TCRT function you may contact the Advanced Product Development group at Alpha Micro to reserve a TCRT code number By using this reservation
209. eakpoints at key points in your program to determine where the calculations are going wrong You can also change the value of a variable Say in the example above you wanted the value of A to be 4 By entering as a direct statement A 4 you can change the value for the duration of the program run There is no limit to the number of breakpoints that may be set in one program The program doesn t run any slower with breakpoints in it than normally Compiling a program does not clear breakpoints If you want to see what breakpoints are set enter BREAK READY BREAK RETN No breakpoints set READY BREAK REUN 30 60 You may start the program over again by using the RUN command it again breaks at the first breakpoint set 4 2CONTINUING AN INTERRUPTED PROGRAM CONT CONT which stands for continue causes a Suspended program to continue execution from the point at which it suspended You may suspend a program by using a BREAK command prior to program execution or by using a STOP statement within the program You may not continue a program after it has finished The following is an example of CONT after a STOP statement has suspended a program Program stop in line 700 READY CONT TURN The program continues by next executing the first line numbered higher than line 700 CONT also continues a program which you have partially executed using the single step feature see below AlphaBASIC PLUS User s Manual Rev 02
210. eans Exclusive OR the IF statement is TRUE only if one of the expressions is TRUE If more than one is TRUE or all are FALSE the IF statement is FALSE EQV which means equivalence causes the IF statement to be TRUE if both expressions evaluate to the same condition TRUE or FALSE NOT negates the value of an expression For example these statements are equivalent IF I 1 THEN GOTO WRONG ANSWER IF NOT I lt gt 1 THEN GOTO WRONG ANSWER 7 40OPERATOR PRECEDENCE The precedence of operators determines the sequence in which mathematical operations are performed when evaluating an expression not having overriding parentheses to define hierarchies We showed you an example of this above in Mathematical Expressions Here is the order of precedence AlohaBASIC PLUS uses AlphaBASIC PLUS User s Manual Rev 02 Page 7 4 Chapter Seven Exponentiation Unary plus and minus Multiplication and Division DIV MOD and FMOD Addition and Subtraction Relational operations comparisons Logical NOT Logical AND OR XOR EQV MIN MAX USING The USING operator allows you to format numeric or string data using a format string For information on USING see Chapter 13 In cases of equal precedence such as between multiplication and division operations are done according to rules of associativity This means operations are done left to right as in the example in section 7 2 above where the multiplic
211. ecord use the WRITEL statement 5 Close the file You cannot sort a random file using XCALL BASORT if you opened the file in RANDOM FORCED mode ISAM FILES A special type of random file opened in INDEXED and INDEXED EXCLUSIVE modes See Chapter 19 for information AlphaBASIC PLUS User s Manual Rev 02 Page 15 8 Chapter Fifteen 15 6FILE LOCKING FOR SEQUENTIAL FILES AMOS automatically locks files so simultaneous update problems do not occur If you OPEN a sequential file for OUTPUT or APPEND the monitor automatically OPENs the file for your exclusive use Since you can modify the file in these modes you must have exclusive use of the file If you OPEN the file for INPUT the monitor automatically OPENS the file for shared use since you aren t going to be changing the file You can specify WAIT FILE when you open sequential files This causes your program to wait if the file you want to access is being used when you try to OPEN it If you do not use this wait clause when you try to access a file and the resource you need is already locked AMOS prevents you from accessing it and returns an error code What happens then depends on your program if your program has error trapping set the actions specified by your error handling routine are performed if your program does not have error trapping set your program is interrupted and you are returned to monitor command level For information on using error trapping to deal with system e
212. ed file at any point other than the beginning You may pass common variables between chained AlphaBASIC PLUS programs either by writing them out to a file and then having the chained program read them back in or by using the COMMON assembly language subroutine For information on COMMON see your AlphaBASIC XCALL Subroutine User s Manual Literal strings can be passed by CMDLIN For more information on CHAIN see Chapter 16 You may not CHAIN from a subprogram You must exit all subcalls and return to the main program first Similarly you may not chain out of a user defined function 9 5DATA See READ RESTORE and DATA below 9 6DEFAULT See SWITCH CASE below 9 7DEFINE Defines a numeric or string constant A constant is a value that does not change during the program The format is DEFINE constant name value constant name is a label for the constant to be defined and value is an expression composed of one of more constant values You cannot use forward references to other defined constants A constant definition makes it easy to change values throughout a program A constant name can only be DEFINEd once during a program and may not be changed Some examples E Control number 5 E Divisor 3 5943 E FACTOR Control number 15 Divisor E Product Name ELAXOR ovv tj j hj nj zou AlphaBASIC PLUS User s Manual Rev 02 Page 9 4 Chapter Nine Don t speci
213. ee section 5 5 1 for details A fuller explanation of the SWA and its size can be found in Appendix l AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 9 PROGRAM STATEMENTS An AlphaBASIC PLUS source program contains statements which are executed in sequence one at a time as AlphaBASIC PLUS encounters them Each of these statements normally starts with a statement followed by optional variables or statement modifiers Many of these statements can also be used in interactive mode as direct statements This chapter lists most of the program statements and gives some examples for clarity The program statements not discussed in this chapter are the statements dealing with file input output and ISAM files See Chapters 15 and 19 respectively for those statements See also the AlphaBASIC PLUS Quick Reference Card for the formats of all AlphaBASIC PLUS statements and commands 9 1AMOS The format is AMOS switch command string where command string is a string expression that is a legal AMOS level command AMOS executes the specified command There must be enough memory left in the user memory partition for the command to execute see MINF in Appendix H It is not a good idea to use the compile or run programs for AlphaBASIC or AlphaBASIC PLUS in this command since there may not be enough memory to execute them The switches are S and T If S is specified no output from the AMOS command is displayed on the terminal This works like
214. el where file channel specifies the file channel number associated with the file you want to close For example if you have previously opened a file called VENDOR DAT OPEN 3 VENDOR DAT 200 1 INPUT to close that file use CLOSE 3 Once the file is CLOSEd the file channel number can be re used for another file 15 9 3CLOSEK Allows you to close a file but keep the system file lock in place so no other program can open the file This allows you to maintain control of the file so you can open it from another program or process The format is CLOSEK file channel where file channel specifies the file channel number associated with the file you want to close If the file was not OPENed with a lock no lock is maintained Be sure your program unlocks the file when done 15 9 4EOF X The EOF function returns a value giving the status of a sequential file whose file channel number is X The file is assumed to be open for INPUT The values returned by the EOF function are 1 if the file is not open or the file channel number X is zero A file channel number of zero indicates the terminal is being used as the file 0 if the file is not yet at end of file 1 if the file has reached the end of file condition Due to the method used by the operating system for processing files the end of file status is not achieved until after an INPUT statement has been executed AlphaBASIC PLUS User s Manual Rev 02 The
215. ement and Chapter 14 for more on MAP AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 7 EXPRESSIONS AND EVALUATION This chapter discusses eWhat is an expression eHow to use mathematical expressions eThe precedence of mathematical operators eConversions and mixed type expressions eType Independence 7 1WHAT IS AN EXPRESSION An expression can contain variables constant values operator symbols functions or any combination of these By expression we mean a section of AlphaBASIC PLUS code treated as a unit within an AlphaBASIC PLUS statement For example in the statement IF Inventory Supplies Used lt 100 THEN GOTO ORDER NEW Inventory Supplies Used lt 100 is an expression f the expression evaluates to true then the instructions in the THEN clause are carried out Even though the expression is made up of two variables a number and two operators it can be seen as one logical unit in the way it functions within the IF THEN statement 7 2MATHEMATICAL EXPRESSIONS A mathematical expression is any expression containing numbers and mathematical operators For example T FIX TOTAL RECS REC SIZ E 512 AlphaBASIC PLUS User s Manual Rev 02 Page 7 2 Chapter Seven Parentheses can be used in most cases to tell AlphaBASIC PLUS which operation to perform first If no parentheses are included AlphaBASIC PLUS follows its rule
216. ementations These features not only enhance the performance of traditional uses of the language but also make business applications easier to program Here are some of AlphaBASIC PLUS s features eMAP statements that make it easy to create hierarchical data structures much like the structured data types available in the COBOL and C languages eThe ability to call assembly language subroutines from within AlphaBASIC PLUS Variable names that may be any number of alphanumeric characters which helps improve program source readability eThe ability to use labels instead of or in addition to line numbers Eliminating line numbers makes updating programs much easier and makes program source code easier to read and understand eThe ability to define your own single and multi line functions eThe ability to use subprograms allowing parts of programs to be compiled separately eThe ability to use AMOS commands from within programs AlphaBASIC PLUS User s Manual Rev 02 Introduction Page 1 3 eA full range of control structures 1 4WHAT CAN ALPHABASIC PLUS DO AlphaBASIC PLUS can be used in two different ways either in interactive mode or by using disk files a compiler and a run time package Interactive mode operates much like a traditional interactive interpreter that is you create alter and test your program while it is in your memory partition This mode is convenient for the creation and debugging of new programs It als
217. ence prepend an at AlphaBASIC PLUS User s Manual Rev 02 Chaining and Subprograms Page 16 9 sign to the argument s name To specify passing by value just used the unadorned variable name For example the following SUBCALL passes the first argument by value the second by reference The third argument passes an entire array by reference and the fourth passes a single array element by value SUBCALL CALCUL START POS QEND POS RARRAY 1 MATCH 3 The argument passing method also has an effect on how values are passed If you pass an argument by reference you must be certain that the size of the argument and the size of the corresponding parameter are exactly the same or you will get memory overwriting and or undefined results This applies particularly to passing arrays to subprograms the receiving formal parameter must be of the same type and size as the array specified in the SUBCALL argument No type conversion or any other operation is done if you pass arguments by reference If you pass an argument by value and the type of the argument is not the same as the type of the coresponding formal aprameter AlphaBASIC PLUS will convert the argument to the type of the formal parameter using its standard rules 16 2 4 3Subprogram Code Subprogram code continues until the end of the file is reached or another SUBPROGRAM is defined 16 2 4 4SUBEND A SUBEND program is used to delineate the end of the code for the subprogr
218. er s Manual Rev 02 User Definable Functions Page 20 3 eDIM statements eRESUME statements into or out of the function RESUME statements within the body of the function are okay eOther function definitions eGOTO statements into or out of the function eCHAIN statements m You cannot pass arrays to a function though you can pass an individual element of an array Here s an example of a multi line function definition DEF FN fact n IF n 0 THEN FN fact 1 ELSE FN fact n FN fact n 1 ENDIF ENDFEN Type conversions on the value are done as needed according to the function name For example if the function name is FN Convert and a numeric value is returned it s converted to a string If you are using FNname the floating point variable is either IEEE or AMOS format depending on which is set If your function uses local variables and does not have any parameters you must define and call it using empty parentheses For example DEF FN TOTAL FUNCTION VALUEI VALUE2 Total FN Total Function 20 4LOCAL VARIABLE AND PARAMETER TYPES Local variable and parameter types are identified just as other AlphaBASIC PLUS variables However a curious situation can arise if you give your local variable or parameter the same name as a variable in the main program The local variable or parameter assumes the type of the main program variable though not its value th
219. ers for AMOS or IEEE floating point variables String variables should be in ASCII format If you use INPUT or INPUT LINE to read data into a variable that contains a null character that variable is terminated by that null character even if other data follows it The only case where this is not true is with unformatted variables Some examples of valid INPUT statements are INPUT A INPUT Enter account name and age ACCOUNT NAMES AGE INPUT AS BS CS INPUT Enter a positive number NUMBER INPUT Q 8 If you specify multiple variables in the INPUT statement you are expected to enter multiple items of data If the data being entered is numeric you may separate data items with either commas or spaces If the data being entered is a string you must separate data items with commas If you mix floating point and string input you must use commas to separate the data being input For example if A B and C are numeric variables and D and E are string variables consider the following legal examples INPUT A B CREN 1 2 3 EUN INPUT A B D C EUN 1 2 DAY 3 N INPUT D E DAY MONTH RETAN For information on the statement to use if you want to enter strings containing commas quotes and other special characters see INPUT LINE below When you use INPUT remember the default size of unmapped string variables is ten characters if you want to use larger strings use the
220. ers use the CPU s native signed integer instruction set for calculations and are stored in native binary form in memory Integers can be one two or four bytes the default in size Integer arithmetic is faster than real number arithmetic This type of variable is defined by using a MAP statement for the variable name and specifying an I data type or by appending a gt to the variable name to specify a four byte integer 6 2 1 1 2Binary Variables Binary variables come closest to the unsigned integer type Binary variables can have different sizes depending on the range of values they need to represent Only 5 byte binary variables are signed variables other shorter binary variables are unsigned Although binary variables represent integers they are always converted to AMOS floating point format even if the I COMPLP switch is used before calculations are done The results of the calculation is converted back to binary before being stored in the results variable Binary variables can only be defined by using a MAP statement specifying a B data type This conversion of binary variables has two important implications 1Binary arithmetic is slower than true integer arithmetic due to the conversions to and from floating point format 2Floating point arithmetic is implicitly inexact due to rounding errors Note for assembler programmers The four byte binary longword variable does not have the same layout in memory as the four byte
221. ess Establish a connection with the remote system and try your program again RESUME cannot be used within functions Use a different method such as a GOTO to redirect RESUME without error A RESUME was encountered but no error has occurred Your program is probably running into your error trapping routine by accident Make sure a GOTO or END or similar statement stops or redirects your program before the error routine RETURN without GOSUB A RETURN was encountered but no corresponding GOSUB was executed Your program is probably running into your subroutine by accident Make sure a GOTO or END or similar statement stops or redirects your program before the subroutine RUNP cannot execute this file The object file needs more features than RUNP has The object file was created with a set of options specified by P in COMPLP This version of RUNP does not support all the requested options Use a later version of RUNP RUNP file is in an incompatible format The program file you tried to RUNP is not a RP file is from a different processor type or was created from a much earlier uncompatible version of COMPLP You may have to rewrite or edit your source file and or re compile it AlphaBASIC PLUS User s Manual Rev 02 Page A 18 Appendix A Significance out of range The value for SIGNIFICANCE must be between 1 and 15 Source code without line numbers Programs in interactive mode must have line numbers add them or run the progra
222. ess c amp C c If the program was changed since it was last compiled RUN automatically recompiles it before executing it Therefore if you need to compile the source program and then run it just use RUN For example READY 10 REM This is a small test program 20 FOR I 1 TO 3 E09 30 PRINT Little tasks make large return EUR 40 NEXT I RUN RETN COMPILING Compile time was 0 003 seconds elapsed time was 0 seconds Little tasks make large return Little tasks make large return Little tasks make large return AlphaBASIC PLUS User s Manual Rev 02 Interactive Mode Page 3 9 CPU time was 0 004 seconds elapsed time was 0 seconds READY You cant run a program other than the one currently in memory while in interactive mode 3 10EXITING FROM INTERACTIVE MODE BYE If you have a program in memory when you use BYE it is erased So if you wish to keep a copy of the program use SAVE before using BYE To exit from interactive mode READY BYE 3 11A HINT FOR THE SYSTEM OPERATOR Because BASICP LIT is re entrant you may load it in system memory to save room in user partitions However since it is a fairly large program you probably only want to put it in system memory if many users use AlphaBASIC PLUS in interactive mode AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 4 MORE INTERACTIVE COMMANDS This chapter discusses eUsing the BREAK command to interrupt progr
223. esulting object program RP file is re entrant and may be loaded into system memory for use by multiple users The RP file can be executed using the RUNP program see below 5 3 1Compiler Options The compiler has a number of optional switches controlling how the compilation works To choose an option include a slash at the end of the file specification you give COMPLP followed by the appropriate letter If you want to add more than one switch add another slash and letter Each letter must be preceded by a slash For example COMPLP PAYROL O N EUR Options are active for the entire source file including subprogram definitions see Chapter 16 Here are the options AlphaBASIC PLUS User s Manual Rev 03 Page 5 4 A C name exp D E H F G L M N 0 Chapter Five Increases the size of the area in memory used to calculate program addresses Normally the compiler uses 16 bits A increases this to 24 bits This adds to the size of your program but lets you transfer control when you use GOTO GOSUB RESUME etc across a span greater than 64K Defines a constant called NAME with a value of EXP NAME is the name of the constant being defined and EXP is an expression consisting of one or more constant values The syntax is the same as that for DEFINE see section 9 7 without using the DEFINE keyword You can define more than one constant from the command line by using multiple C
224. etter U With LI Grave 250 FA Latin Small Letter U With LI Acute 251 FB Latin Small Letter U With LI Circumflex 252 FC Latin Small Letter U With LI Diaeresis 253 FD Latin Small Letter Y With LI Acute 254 FE Latin Small Letter Thorn LI 255 FF Latin Small Letter Y with LI Diaeresis 1 This code point is used by National Replacement Character Sets 7 bit character sets Devices using such an NRC will not print the glyph shown neither will it print glyphs for code points above 127 2 ISO may be reclassifying these code points as Latin Letter as certain Scandinavian languages use these characters as a complete letter not as a ligature Type The characters are broken down into character types by Unicode Cc LI Lm Lu Nd Pd Pe Po Ps Sc Sm So Zs Control or Format Character Lowercase Letter Modifier Letter Uppercase Letter Decimal Number Dash Punctuation Close Punctuation Other Punctuation Open Punctuation Currency Symbol Math Symbol Other Symbol Space Separator AlphaBASIC PLUS User s Manual Rev 02 APPENDIX G ERR 3 ERROR CODES These are the error codes returned by ERR 3 with their meanings See Chapter 17 for information on trapping and correcting these errors ERR 3 returns a 16 bit number from the JOBERR monitor call See your Monitor Calls Manual for more information The first three bits represent the severity of the error CODE SEVERITY 0 Operation completed no errors warnings if
225. examples of INPUT LINE INPUT LINE AS INPUT LINE ENTER YOUR FULL NAME PLEASE NAMES You may also use the INPUT LINE statement to read data from a sequential file For more information on using INPUT LINE and files see Chapter 15 9 22INPUT RAW INPUT RAW allows you to input special characters to your program The format is INPUT RAW prompt string variable variable s The variable s MUST be unformatted See Chapter 14 for information on unformatted data INPUT RAW inputs in data mode It accepts characters from the keyboard until all of the variables are filled It accepts but otherwise ignores any special characters such as carriage returns linefeeds C etc The characters entered are NOT echoed back to the terminal 9 23LET The format is LET variable expression Assigns a value to a specific variable during execution of the program You do not have to specify the LET keyword in an assignment statement Some examples LET A5 12 4 LET SUM 4 5 Al SQR B1 LET CS JANUARY A5 12 4 SUM 4 5 Al SOR B1 CS JANUARY AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 19 9 24LOOP See DO WHILE UNTIL LOOP above 9 25NEXT See FOR TO NEXT and STEP above 9 26NO DIVIDE BY 0 Turns on the Divide by zero error When this statement is executed all attempts to divide by zero result in an error Thi
226. f line characters all terminate numeric data and then are bypassed Null characters terminate all but unformatted variables As with the non file version of the INPUT statement described in Chapter 9 the data being input must be in the proper format In the case of the file version of the INPUT statement you must be aware of the rules for properly separating data when you write the data out to a file using the PRINT statement Here are the rules eSeparate all floating point data with spaces or commas Separate all string data with commas elf you have both floating point and string data in the same statement separate them with commas Keep in mind the characteristics of the PRINT statement when writing data to a file so you do not conflict with the rules above See Chapter 9 for details on PRINT Using PRINT to send data to a file formats that data in exactly the same way it does if you use PRINT to send data to the terminal screen Remember PRINT does not separate the data with commas for you For example the following statement PRINT 100 HELLO AGE DATE sends this to the file HELLO AGE DATE If you try to use INPUT to read that data in the file into three different string variables the first variable contains HELLO or HELLO AGE DATE and the other two string variables contains null data In the first case above we are assuming no STRSIZ command is set so the first string
227. f program code operating as a unit to do a task The main program calls the subroutine and when it has done its work it returns control back to the next line of the main program The numbers representing the elements of an array A part of a string A substring is produced by use of substring modifiers or string functions For example if you had a string and you only wanted to print the first five characters rather than the whole string you could say PRINT INPUT STRINGS 1 5 The first five characters printed are a substring of INPUT STRING An option that can be added to a command An area of memory available to all users of the computer Any file loaded into this area by a SYSTEM command in your system INI file can be used by any person or program The advantage of using system memory is if a file is used regularly by many users each user doesn t have to load a copy of it into their user memory saving time and memory AlphaBASIC PLUS User s Manual Rev 02 Glossary TRANCENDENTAL FUNCTION UNARY Plus Minus USER MEMORY VARIABLE WILDCARD XCALL Page 9 An AlphaBASIC PLUS function that often results in an irrational number for example a number that repeats endlessly or a number like pi which never ends The SQR square root function and the SIN sine functions are good examples of this An operative changing the value of a number or variable to positive or negative Fo
228. f the Arithmetic Stack is controlled by the STACK setting in the BPR file AlphaBASIC PLUS User s Manual Rev 02 Memory Page H 5 eThe string work area The size of this area is set by the compiler as described in Appendix l eDDBs buffers and internal variables for file IO within AlphaBASIC PLUS eHolding RP and SPG files if they are not loaded into system or user memory If RUNP tries to allocate memory in the heap and there s insufficient contiguous free memory in the Stack Heap module RUNP will abort with a trappable runtime error 3 Out of memory The C Stack is used internally by RUNP to carry out its own execution As such much of the size requirement is beyond an AlphaBASIC PLUS programmer s reach The complexity of a given AlphaBASIC statement may have a small impact on the Stack s size The biggest contributor to large C Stack sizes is having nested user defined functions and subprograms The size of the Heap and C Stack are controlled by the MINS MAXS and MINF settings in the BPR file as outlined above AlphaBASIC PLUS s Arithmetic Stack is used for General execution of each AlphaBASIC PLUS statement Loops such as FOR loops or DO WHILE loops push control variables onto the Arithmetic Stack The more nesting of these structures the more Arithmetic Stack space is required eHolding actual parameters for user defined functions If you call a particular function recursively each level of recursion will push it
229. f the function definitions Nested INCLUDE files are not permitted Your program contains an INCLUDE command specifying a file which also contains an INCLUDE command You either have to remove the INCLUDE command from the second file or change the way you access that code 2NEXT without FOR A NEXT statement was encountered without a matching FOR statement Check your program for the extra NEXT statement AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 15 2No breakpoints set This message just informs you there are currently no breakpoints set in your program 2No source program in text buffer You tried to compile when there was no program in memory Load or create a program before trying to compile again Not enough memory to initialize See your System Operator about freeing up more of your user memory partition or about increasing it Not enough memory to load XCALL routine RUNP could not locate an XCALL in system or user memory It tried to dynamically load the XCALL from disk into the reserved free memory area at the top of the job s partition but there was insufficient memory to do so Either load the XCALL into system or user memory before execution or adjust the memory allocation as described in Appendix H Numeric overflow A floating point overflow occurred during a calculation This means the calculation went beyond the capabilities of the computer in some way usually the number was too large Check y
230. fy a or to indicate an integer or a string the constant takes the type of the value given If the constant is used in an equation or comparison with another variable type AlphaBASIC PLUS does the necessary conversion if possible Constants can also be defined from COMPLP s command line See the section on compiler options in Chapter 5 for details 9 8DIM Defines an array which is allocated dynamically at execution time The format is DIM variablel exprl exprN variableN exprl exprN Once allocated an array can t be redimensioned during the execution of the program If you use DIM statements with mapped variable arrays you get a run time error There is no set limit to the number of subscripts that may be used to define the individual levels within the array the size of your program and the amount of memory you have determine how many levels you can have In most cases you are able to define many more levels than you actually need The statement DIM A 20 defines an array with 20 elements referenced as A 1 through A 20 Multiple arrays may be dimensioned by a single DIM statement by separating them with commas For example DIM A 20 B 15 C 10 Subscripts are evaluated at execution time and not at compile time thereby allowing variables as well as numeric constants to be used as subscripts The statement DIM A B C allocates an array whose size depends on the actual values of B and C at the time
231. g is cleared and control reverts to the calling program as if no error had occured If the SUBEND statement specifies a parameter with a non zero value control is passed back to the calling program and immediately an AlphaBASIC PLUS error with an ERR O of that number is triggered as if the error happened in the SUBCALL statement The value of ERR 1 corresponds to the value of the line number of the SUBCALL line if set If the calling program has an ON ERROR set active that set takes over control If not the program is terminated To propagate the same error code back up to the calling program use SUBEND ERR 0 But note that there is no restriction to using the same SUBEND value as the original error code However for future compatibility the value passed back must be a legal defined AlphaBASIC PLUS error code see Chapter 17 16 2 6Using Subprograms Because subprograms are compiled separately they can only work with variables defined within them or variables explicitly passed to them For example MAIN PROGRAM A 5 B 7 SUBCALL FIGURE A PRINT Program answer A B END SUBPROGRAM FIGURE PARAMETER A F 6 MAP1 B F 6 B 10 PRINT Subprogram answer A B SUBEND The program above prints Subprogram answer 50 Program answer 35 As you see the variable B is a different local variable in the main program and the subprogram Only t
232. g is needed to fix the problems An alphanumeric character marking a division between two pieces of data For example in the date display 12 04 86 the slash is a delimiter A dash is also a common delimiter An area of memory on a hard disk containing a program text or data file Unless such a file is erased it resides permanently on the disk AlphaBASIC PLUS User s Manual Rev 02 Glossary Page 3 DYNAMIC SCOPING Scoping refers to the range over which a particular variable binding is accessable Dynamically scoped means a binding is accessable based on how the program is run hence dynamic as opposed to how a program is written which is statically scoped For example DEF FNA1 X Y Z Z 1 FNA1 FNB 1 ENDEN DEF FNA2 X Y Z Z 2 FNA2 FNB 1 ENDEN DEF FNB Y Y Z Z 100 A FNA1 10 20 B FNA2 3 4 The question is What binding of Z is in effect when FNB is executed Z is given the global value of 100 However when FNA1 is called the value of 100 is shadowed since Z is declared local to the function Z is given the value of 1 When FNB is executed from FNA1 the binding of Z with 1 is in effect This is the value FNB adds to Y returning 2 When FNA1 returns the global binding is restored Z is once again 100 When FNA2 is called the global binding of Z gets shadowed again and the local value becomes 2 This time when FNB is called the value added to Y is
233. gles break point breakpoints You may have 16 Execute from cursor to end of subroutine Takes you to command mode Toggles subroutine mode When active single stepping through a program executes a subroutine as if it were one line AlphaBASIC PLUS User s Manual Rev 02 The AlphaBASIC PLUS Debugger Page 22 3 22 5COMMAND MODE DB has two modes screen mode and command mode Screen mode shows you your source code and its execution displays Command mode like command mode in AlphaVUE or AlphaF IX lets you enter commands In command mode you see the command mode prompt gt Commands mode commands are case insensitive and echo in upper case However variables and other references within the program being debugged are case sensitive Command mode knows all the legal commands and all your program s variables and labels and won t let you enter anything that would not make up a legal command the terminal beeps anytime you press an incorrect key Commands which display information fill one screen at a time The down arrow key J or ea J C T scrolls you to the next screen c8 C 8 brings you back to the first screen Command mode lets you edit your command mode typing using the following keys control sequences SEQUENCE FUNCTION Executes command If command is unique but not full fills in the rest of the command name and executes it If command is not complete waits for next word If not unique DB selects first poss
234. gram to be shared amongst multiple programs subprograms and users while keeping just a single copy of the SPG file and its source file This can reduce memory overhead as well as program maintenance Updating application suites can be easier if just a few SPG files are updated rather than having to change many larger RP files An SPG file cannot be executed directly by RUNP It can only be called from a calling program by using the SUBCALL statement Just like subroutines and user defined functions it is possible to call a subprogram from within a subprogram just as you can call subroutines and user defined functions from within subprograms The visibility rules still hold an internal subprogram can only be SUBCALLed from the main program and other internal subprograms within the RP file An external subprogram can be SUBCALLed from the main program internal subprograms within the main program and other external subprograms Use a little caution when nesting SUBCALLs lt could cause an overflow of the stack area resulting in an error and the termination of your program run See Appendix H for details 16 2 4Subprogram Components A subprogram is made up of a number of components as shown below AlphaBASIC PLUS User s Manual Rev 02 Chaining and Subprograms Page 16 7 SUBPROGRAM name PARAMETER definition s local variable definitions s program statement s SUBEND error number
235. guments devn monitor command p pn arguments devn CMD file name p pn devn DO file name p pn arguments CHAIN causes control to be passed to the specified AlphaBASIC PLUS program command file or monitor command program The program name may be a full file specification including device and account specifications Certain AMOS commands and DO files can have various arguments specified with them the way you enter the command at AMOS level is the way you enter it after the CHAIN statement The RUNP command also allows argument s see the CMDLIN statement in Chapter 10 CHAIN causes the current program to be cleared from memory The specified file is then located and executed from the beginning A chained AlphaBASIC PLUS program must be a fully compiled program with the extension RP in order to be run by the CHAIN command It may be in user memory AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 3 having previously been loaded with the monitor LOAD command or it may be in system memory the System Operator may place a file in system memory by modifying the system initialization command file If it is not already in memory it is loaded from the specified disk account into user memory and then executed If it can t be found you are returned to AMOS level Here are some examples of CHAIN CHAIN PAYROL 70 CHAIN DSK1 ACTRUN CMD 100 7 There is no way to start the chain
236. h ERE 3 8 3 9 RUNNING A PROGRAM HUN 2 5 2524 24242005 RR ERR RETE 3 8 3 10 EXITING FROM INTERACTIVE MODE BYE 3 9 3 11 A HINT FOR THE SYSTEM OPERATOR ovnis 3 9 AlphaBASIC PLUS User s Manual Rev 04 Page ii Table of Contents CHAPTER 4 MORE INTERACTIVE COMMANDS 4 1 INTERRUPTING A PROGRAM RUN BREAK 20055 4 1 4 2 CONTINUING AN INTERRUPTED PROGRAM CONT 4 2 4 3 STOPPING A PROGRAM RUN rtg tate m ees 4 3 4 4 LOADING A PROGRAM INTO MEMORY LOAD 4 3 4 5 THE SINGLE STEP FEATURE 2 csse ARRIERE eet i eae bee 4 4 CHAPTER 5 WRITING PROGRAM FILES 5 1 CREATING A PROGRAM a oran RUE E Reese qus 5 1 52 PROGRAM FORM 4 225 taste rn das pda 5 1 5 3 COMPILING A PROGRAM cevopccrosiaran ta iaa Rx RR 5 3 5 3 1 Compller OPINAS secando aa 5 3 5 4 COMPILATION CONTROL 2 02 cei dee e a a e 5 5 5 4 1 Including Other Files in Your PrograM o o oo 5 7 5 4 2 Conditional Compilation nesae aaaeeeaa 5 8 5 4 8 PRAGMA Setting Compiler Options 5 9 5 4 3 1 PRAGMA and Command Line Switches 5 9 5 4 3 2 Setting String Work Area Size 5 10 5 5 RUNNING A PROGRAM 4 sau oso ute toe EAE CRT ERES 5 11 5 5 RUNTIME Options ute oe eee Ser RH et eee 5 11 CHAPTER 6 VARIABLES 6 1 NAMES Consiste 6 1 6 1 1 Variable Label and User Defined Function Names 6 1 6 1 1 1 Variable Names 220 0c ee eee 6 2 6
237. h to use WAIT FILE in case the file is in use when you try to open it 4Use READ and WRITE statements specifying the file channel number associated with the file by the OPEN statement to read and write data in the file Remember to change the record number variable to the correct record number before performing each read or write operation so you access the logical record you want Make sure the record number variable contains a valid record number before performing the file 1 O or you get an error 5When you are finished reading and writing the file use the CLOSE statement to close the file USING RANDOM FILES IN RANDOM FORCED MODE 1When a random file is open in this mode a READ operation forces a disk access even if the requested block is already in memory Likewise if a WRITE is performed the block is reread modified and forced out to disk even if the buffer is not yet full This mode makes it possible for users to share random files RANDOM FORCED causes the file to be OPENed for shared access You may want to specify WAIT FILE and or WAIT RECORD also in case the file or record is in use when you try to access it 21f you want to only read the contents of a record use the READ statement 3lf you want to read in and then update use the READL statement Then use either a WRITE statement to write the record back to the file or use an UNLOKR statement to unlock the record again 4Jf you want to write to a new or blank r
238. haBASIC PLUS statement A process by which a file being used by one program is locked so any other program trying to access it is told the file is in use This prevents problems occurring from two programs working on the same file at the same time A real number a number that may contain a decimal part For example 4 175 Called floating point because the number of digits both right and left of the decimal point may vary so the decimal point has no fixed position A place holder in a definition to be filled at run time with an ACTUAL PARAMETER see above For example in DEF FN TEST A B A B 7 The variables A and B are formal parameters Whatever actual values are specified when the function is called are used to compute A B 7 A variable whose value can be accessed anywhere in the program except when shadowed by a local variable see SHADOWING below See also LOCAL VARIABLE AlphaBASIC PLUS User s Manual Rev 02 Glossary INCREMENT INDEXED FILE INPUT INTEGER NUMBER INTERACTIVE ISAM LABEL LIBRARY LIST LITERAL Page 5 The process of increasing the value of a variable by a constant amount For example the statement NUMBER NUMBER 1 Increments the variable NUMBER by one An ISAM file see ISAM below Any data coming into the program or computer Input may come from the user at the keyboard from a data file or from some other ex
239. has not been DIMed or 3 the array has not been referenced before the XCALL which would cause an automatic allocation of an array of ten elements Undefined line number or label The line number or label specified in a GOTO GOSUB or ON ERROR GOTO is not defined in the program Correct the reference or add the proper line number or label Unknown switch See the list of available switches and try again Unsupported feature Unsupported function Your program attempted to use a feature not supported by AlphaBASIC PLUS Check this manual for the features AlphaBASIC PLUS supports Unmapped variable You compiled a program using the M option and COMPLP encountered an unmapped variable MAP the variable or do not use the M option Unterminated string Add a closing quote mark to the string definition Variable defined more than once Re name or remove one of the duplicate definitions Variable expected Adjust your code so the expected condition is fulfilled Variable must be on an even byte boundary A variable is being used in a way that demands that it is located on an even byte boundary but instead it is located on an odd byte boundary in memory Adjust your MAP statements to force placement on an even byte boundary or define the variable as a MAP 1 variable which forces even boundary alignment AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 21 WHILE or UNTIL expected Adjust your code so the expected cond
240. have size 1 2 or 4 and IEEE variables have size 4 or 8 lllegal STRSIZ argument Check your syntax and the number you specified The argument must be less than 65 535 AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 11 lllegal subroutine name The name specified as a subroutine is not valid Names used must be legal filenames with a SBR or XBR extension lllegal subscript The subscript expression is not valid Subscripts must be positive whole numbers lllegal TAB format Your program incorrectly specified a TAB function Check the syntax and check to see there are not more than two numbers in the parenthesis lllegal token Contact Alpha Microsystems and report the problem and how it happened lllegal type The type of the variable you specified is inconsistent with the function you tried to use it with Check the syntax of the function or statement and try again lllegal type code The variable type code used in a MAP statement is not valid Check your number against the legal values allowed lllegal user code The specified PPN was not found on the specified device or is not in a valid format If you get this message while using File Locking it may mean your program tried to access or lock a resource in a protected account lllegally defined constant Check the rules for constants and re define the constant Inappropriate file IO You have tried to access a random contiguous file by using sequential
241. he ECHO or NOECHO commands any changes you make to your job s or the system s environment will be visible to the calling program after the SUBEND AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 17 ERROR TRAPPING This chapter discusses eWhat is error trapping eThe ON ERROR GOTO statement eThe ERR X function eThe RESUME statement eControl C trapping In addition we include two sample programs illustrating how to use error trapping 17 1WHAT IS ERROR TRAPPING Normally when an error occurs during the run of an AlphaBASIC PLUS program an error message is printed and the program run is halted Using a technique called error trapping you can catch the error before the AlphaBASIC PLUS processor stops your program giving you a chance to correct the error This has the advantage of allowing your program to continue running and gives you more control over what is happening in your program Many of the errors you encounter can be handled this way 17 2THE ON ERROR GOTO STATEMENT Error trapping is turned on and off by using the ON ERROR GOTO statement in one of two forms The first form specifies a line number or label within the program When the program encounters this ON ERROR statement it stores the line number and turns error trapping on If an error occurs any time after this AlphaBASIC PLUS transfers control to the the line number or label you specified Here is what such a statement looks like ON ERR
242. he Gamma function and can be used with all positive real numbers and all negative non integer real numbers AlphaBASIC PLUS User s Manual Rev 03 Functions Page 10 3 10 1 5FIX X Returns the integer part of X fractional part truncated For example READY PRINT FIX 50 4685 50 PRINT FIX 1 9 1 10 1 6INT X Returns the largest integer less than or equal to the argument X The only time you see a difference between using INT and FIX is if you are working with negative numbers For example the largest integer less than or equal to 23 4 is 23 However the largest integer less than or equal to 23 4 is 24 FIX returns 23 10 1 7LOG X Returns the natural base e logarithm of the argument X The logarithm is the number the constant e 2 7182818285 must be raised to the power of in order to get X 10 1 8LOG10 X Returns the decimal base 10 logarithm of the argument X The logarithm is the number 10 must be raised to the power of in order to get X 10 1 9RND X Returns a random number between O and 1 The number returned is based on a previous value known as the seed The argument X controls the number to be returned If X is negative it is used as the seed to start a new sequence of numbers If X is zero or positive the next number in the sequence is returned depending on the current value of the seed this is the normal mode The RANDOMIZE statement may be used to create a number which is truly random and
243. he output and ignore all other time formatting flags Affects numerical output for day month and year only If on leading zeros are suppressed on all elements This produces output suitable for use in an isolated message If off leading zeros are added if appropriate producing output of a constant width that is useful for printing tables Note that full month and weekday texts are never columniated and time formats always have leading zeros Overridden by Option 18 See also Option 19 Output the time before the date else the time will follow the date DATE FORMATTING Date Punctuation 7 8 20 21 Date punctuation control can be overridden by Option 21 Both off Use dashes as 20 Feb 82 7 only Use spaces as in 20 Feb 82 if Option 6 is on and Option 3 is off add a comma as in February 20 1990 8 only Use slashes as 2 20 82 Both on Use the character defined as the date separator in the job s language definition file Do not output any commas in the date string Overrides Option 2 and Option 6 Do not output date punctuation Overrides Options 7 and 8 Date Ordering 6 16 Output the day of the month after the month otherwise output it before Ignored if Options 7 or 8 are set A comma is appended if the day is immediately followed by the year and the month is not output as a number If set the year precedes the day and month which are printed in the order specified by Option 6 Date Items Output
244. he status variable ISAM NF 3 Key not found ISAM EQ 0 Key found Examples FIND 1 ISAM KEY 1 gt JONES FOUND KEY FIND NEXT 2 NEXT KEY FIND PREV 3 PREV KEY 19 3 6UPDATE RECORD The UPDATE RECORD statement is used to update the file All of the indices are automatically updated based on the data in the file as to where each key is located within the record The format is UPDATE RECORD file channel expression list Because the UPDATE statement updates the last record successfully obtained by a GET or located by a FIND and because failure of a GET or FIND operation doesn t include the updating of the current relative record number you should rigorously check the status after these operations Failure to do so may result in the update going to the wrong record AlphaBASIC PLUS User s Manual Rev 03 19 3 9RELEASE RECORD Page 19 6 Chapter Nineteen Updated records must be currently locked by the program An attempt to update an unlocked record results in a trapping error UPDATE RECORD does not affect the lock status of a record Any key including the primary can change during an update The key must have been read by a GETLOCKED GETNEXTLOCKED or GET PREV LOCKED statement to lock it before the update An update failure causes an error trap The system DDB error code giving the reason for the error is in the error status
245. he table reflects version 1 0 267 Other versions may have different values for the factors H 2MEMORY MANAGEMENT You can control AlphaBASIC PLUS s allocation of memory by using a BPR file H 2 1The BPR file The name of a BPR file is the same as the RP file to which it applies A BPR file is read only when RUNP LIT initializes itself Therefore typing RUNP MYFILE from the command line will cause RUNP to look for and process MYFILE BPR to configure memory However doing a CHAIN MYFILE or a SUBCALL MYFILE will not cause a new BPR file to be processed the BPR file settings of the existing RP file will still be in use To force CHAIN to read the target RP file s BPR file use CHAIN RUNP MYFILE A BPR file is a standard ASCII file which you can create through a text editor such as AlphaXED or AlphaVUE It consists of one or more lines with each setting defined on a separate line The BPR file must be located on the following search path User memory RP file s device drive and PPN RP file s device drive p 0 RP ersatz usually DSK0 7 35 If the RP file was loaded into MEM then the user s current login details are used instead of the RP file s details The contents of the BPR file are in the following format setting value H 2 2 BPR File Settings The context of each setting is explained in the next section The valid settings in the BPR file are DELTA The minimum number of by
246. he variable A has the same value in both since it was passed User defined functions and subroutines are private to the environment a subprogram cannot call a user defined function in a calling program for example AlphaBASIC PLUS User s Manual Rev 02 Chaining and Subprograms Page 16 11 The separate environment also means that you cannot GOSUB CALL RESUME or GOTO into or out of a subprogram You must not CHAIN out of a subprogram You must SUBEND back through all the calling subprograms to the main program the RP program before CHAINing You may need to adjust the size of the String Work Area in certain cases See Appendix for details 16 2 7Saved Runtime Environment The saved calling program environment currently includes the following elements ON ERROR ON CTRLC SCALE SIGNIFICANCE and data pool information Currently FILEBASE STRSIZ a compile time setting and DIVIDE BY O settings are global in scope changes by the subprogram will be seen by the calling program However this may change in future versions of AlphaBASIC PLUS so the recommended practice is to explicitly set them in each subprogram If you open files in the calling program they will remain accessible in the subprogram If you open files in a subprogram they will remain accessible to the calling program after a SUBEND even after the subprogram is exited unless they are explicitly closed If you use the AMOS command to change system systems or t
247. helpful for checking for null strings For example IF LEN VARS 0 THEN GOTO RE INPUT 10 3 8MID AS X Y Returns the substring composed of the characters of the string expression A starting at the Xth character and extending for Y characters A null string is returned if X is greater than the length of A For example READY STRSIZ 60 tum AS The quick brown fox jumped over the sleeping dog tW PRINT MID A 17 15 fox jumped over If X is negative the starting point of the MID string is X number of characters from the end of the string For example READY STRSIZ 60 Ey AS The quick brown fox jumped over the sleeping dog ty PRINT MID A 12 8 sleeping If Y is negative the MID string starts at a point Y distance before the X starting point For example READY STRSIZ 60 EUR A The quick brown fox jumped over the sleeping dog ty PRINT MID A 12 8 quick br AlphaBASIC PLUS counts the positions even if the parameters go beyond the string s endpoints For example AlphaBASIC PLUS User s Manual Rev 03 Functions Page 10 9 READY STRSIZ 60 EN A Cost Accounting UA PRINT MID A 20 15 Accounting 10 3 9RIGHT A X Returns the rightmost X characters of the string expression A For example READY STRSIZ 60 EUN A I THINK THEREFORE I AM EN PRINT RIGHT A 4 I AM PRINT RIGHT 1234 2 34 Remember you can use numeric argu
248. ibility filled out in reduced intensity and waits A second executes this command or you can type over with correct command era J C w and e J C 8 let you sequence through possibilities Returns you to screen mode 18 or Like WN except won t execute partial commands It fills in partial SPACE BAR commands and waits RUBOU or Moves cursor back one space deleting character it encounters L CR Backs up to last command completion Deletes current word of command Displays in reduced intensity the first possible completion for a partial command Each use after displays the next possible completion Cera v Deletes entire current word of the command and backs you up to the last character of the previous word em Cz Deletes entire command line AlphaBASIC PLUS User s Manual Rev 02 Page 22 4 Chapter Twenty Two The things you can do in Command Mode are 22 5 1Print Variable Value If you want to see the value of a variable enter or PRINT followed by the variable name For example gt inventory number 1098 If you have a local variable inside a function you will not be able to display the value You will either see a null value or if you have a global variable with the same name the value of the global variable 22 5 2See Variable Information To see information about a variable enter and the variable name For example gt inventory number ETA inventory numbe
249. ication Program Cc Command Zs Po Sc Sc Sc Sc So So Lm So So Ps Sm Po So Lm So Page F 6 Appendix F Char Also Octal Decimal Hex ISO IEC 10646 1 1993 E Also Known As Type See acter Called Value Value Value and Unicode 2 0 Name Note E 261 177 B1 Plus Minus Sign Sm 2 262 178 B2 Superscript Two So 2 263 179 B3 Superscript Three So 264 180 B4 Acute Accent Lm u 265 181 B5 Micro Sign So 1 266 182 B6 Pilcrow Sign So 267 183 B7 Middle Dot Po 270 184 B8 Cedilla Lm l 271 185 B9 Superscript One So 7 272 186 BA Masculine Ordinal Indicator So 273 187 BB Right Pointing Double Pe Angle Quotation Mark Ya 274 188 BC Vulgar Fraction One So Quarter Ye 275 189 BD Vulgar Fraction One Half So 34 276 190 BE Vulgar Fraction Three So Quarters 277 191 BF Inverted Question Mark Po 300 192 CO Latin Capital Letter A With Lu Grave 301 193 C1 Latin Capital Letter A With Lu Acute 302 194 C2 Latin Capital Letter A With Lu Circumflex 303 195 C3 Latin Capital Letter A With Lu Tilde 304 196 C4 Latin Capital Letter A With Lu Diaeresis 305 197 C5 Latin Capital Letter A With Lu Ring Above 306 198 C6 Latin Capital Ligature AE Lu 2 307 199 C7 Latin Capital Letter C With Lu Cedilla E 310 200 C8 Latin Capital Letter E With Lu Grave E 311 201 C9 Latin Capital Letter E With Lu Acute 312 202 CA Latin Capital Letter E With Lu Circumflex 313 203 CB Latin Capital Letter E With Lu Diaeresis i 314 204 CC Latin Capital
250. if Control C or error trapping is on For example A 3 EUR INPUT A RETURN PRINT A EUN 3 If you press UN or c amp J c in response to a data request and the INPUT statement contains several variables AlpghaBASIC PLUS skips over any variables remaining in the INPUT statement leaving their values unchanged An example might help to clarify If you run the following program START INPUT Enter day month year DAY MONTH YEAR PRINT Day DAY Month MONTH Year YEAR PRINT GOTO START it looks like this AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 17 Enter day month year 21 4 mmy RETURN Day 21 Month 4 Year 0 Enter day month year 8 REUR 2 E Day 8 Month 4 Year 0 Enter day month year 31 12 1980 tmm Day 31 Month 12 Year 1980 3 Enter day month year CmR CC Operator interrupt in DAY RP You may also use the INPUT statement to read data from sequential files For more information on this use of the statement see Chapter 15 9 21INPUT LINE The format is INPUT LINE prompt string variable Although you may specify a numeric variable the real purpose of INPUT LINE is to let you enter string data from your terminal including commas quotation marks blanks and other special characters You usually want to use INPUT see the section above for inputting numeric data or multiple items
251. ine AlphaBASIC PLUS User s Manual Rev 03 Page 5 8 Chapter Five 5 4 2Conditional Compilation The IF statement lets you conditionally compile sections of code In this example DEFINE FLAG 1 IF FLAG 1 section of AlphaBASIC PLUS code ELSE section of AlphaBASIC PLUS code ENDIF The first section of code is compiled since FLAG is defined as one By redefining FLAG to 0 you can change to compiling only the second section of code by changing just the definition statement Here s another example DEFINE FLAG 1 IF FLAG 1 section of AlphaBASIC PLUS code ELSE ERROR Code incomplete Change FLAG to 1 and re compile ENDIF In this case if FLAG is set to not equal 1 the compiler aborts with the message Code incomplete Change FLAG to 1 and re compile displayed AlphaBASIC PLUS defines two special constants that can only be used with conditional compilation directives BASIC and BASICP BASIC always returns a FALSE value in AlphaBASIC PLUS it is used by sections of code that should only be compiled under AlphaBASIC 1 4 a predecessor of AlphaBASIC PLUS BASICP always returns a TRUE value in AlphaBASIC PLUS IFDEF works much like IF except it looks for whether or not a constant is defined For example AlphaBASIC PLUS User s Manual Rev 03 Wri
252. ing a brand new file If a file of the same name and extension already exists in the account you are writing to AlphaBASIC PLUS automatically deletes the old file for you before it opens the new output file Therefore if you don t want AlphaBASIC PLUS to delete an existing file be sure to use the LOOKUP command before you open a file for output to make sure such a file does not already exist If the file already exists you can go ahead and open it if you want AlphaBASIC PLUS to delete the existing file for you or you can choose another file name and use the LOOKUP command again to see if that file already exists 2Use the OPEN statement to open the file for OUTPUT Your file is then OPEN for exclusive use no other program can access it while you have it open 3Use PRINT statements specifying the file channel number associated with the file by the OPEN statement to write data to the file 4 When finished use the CLOSE statement to close the file USING SEQUENTIAL FILES IN APPEND MODE 1Use the OPEN statement to open the file for APPEND The file is open for exclusive use no other program can write to it while you have it open If the file does not exist it is created AlphaBASIC PLUS User s Manual Rev 02 Page 15 4 Chapter Fifteen 2Use the PRINT statement specifying the file channel number associated with the file by the OPEN statement to write data to the end of the file 3When finished use the CLOSE statement to close
253. ing with String Variables Page 8 3 STRSIZ 50 RUN AS Form X 913 fE B Prototype Ledger Screen tUm cS Schedule A 40 Deductions RETURN ANSWERS AS BS CS 6 30 fE PRINT ANSWERS EUAN X 913 Prototype Ledger Screen ANSWERS ABLE AS QQ34 4 17 EUR PRINT ANSWERS EUA EForm X 913 QQ The mode independence feature allows substring modifiers to be applied to numeric expressions See Chapter 7 for information on mode independence When a string is returned and the destination is a numeric variable another conversion is made on the substring to return a numeric value For example INPUT Enter two numbers NUMBER NUMBER2 SUM NUMBER NUMBEI NUMBER NUMBER2 SUM Test rightmost digit H H IF SUM 1 1 0 THEN PRINT Divisible by 5 and 2 IF SUM 1 1 5 THEN PRINT Divisible by 5 Be sure you understand the concept of mode independence before you use substring modifiers or you may get answers you don t expect For example the second and third lines in the small program below return different answers even though the subscripting is performed exactly the same in both cases This is because the mode independence feature examines the data type of the destination variable before doing the operations When it scans the second line AlphaBASIC PLUS knows a string result is expected because STRING is a
254. ing you to make such adjustments The statements in which you use the USING modifier take these forms variable expression USING format string PRINT expression USING format string PRINT USING format string expression list where expression is usually a numeric or string constant or a numeric or string variable You can also use instead of the word PRINT As an example of PRINT USING if you want to format the number 2345 678 with the format string you could say NUMBER 2345 678 USING SS or PRINT 2345 678 USING SS or PRINT USING SS 2345 678 You may use the first and second formats only for numeric data you may use the third format for string and numeric data Also remember USING has the lowest precedence of all operators Therefore all other operations in expressions surrounding the USING operator are performed before formatting is done For example READY PRINT 23 4 USING GEA 27 0 The format string may be a string expression for example MID A 4 5 a string literal for example a string constant or a string variable for example MASK If you use the third PRINT USING variant above you may supply a list of expressions to be formatted separating the expressions with commas as with the regular PRINT statement for example PRINT USING A B C D E The mask can consist of multiple fiel
255. into system memory Once created by the compiler an object program also known as a compiled program is also re entrant and sharable and may be placed in system memory or in the AlphaBASIC PLUS program account BP DSKO 7 35 so it may be shared by all users on your system AlphaBASIC PLUS User s Manual Rev 02 Page 1 4 Chapter One 1 5WHAT TYPES OF DATA DOES ALPHABASIC PLUS SUPPORT AlphaBASIC PLUS supports the following data formats FLOATING POINT Numbers including a decimal fraction STRING ASCII alphanumeric characters BINARY Whole numbers stored in binary computed as floating point UNFORMATTED Special variables set up by MAP statements INTEGER Whole numbers stored and computed in binary All data formats may be simple variables or array structures In addition the unique memory mapping system allows you to specify the ordering of variables in special groups This grouping of variables makes them easier to use and makes your program more efficient The MAP statement is similar to the data formatting capabilities of the COBOL language or a C structure and lends itself well to business applications where the grouping of related information is important Variable names are not limited to the single character and single digit format of many BASICs but may be any reasonable number of alphanumeric characters in length since lines are limited to just under 1000 characters this defines the outer limits of variable size
256. irect statement just prior to the actual running of a test program Of course any SIGNIFICANCE statements encountered during the execution of the program reset the value SIGNIFICANCE has no effect on the printing of integer values 9 44SLEEP Causes the job to sleep for a specified number of seconds The format is SLEEP time in seconds For example SLEEP 10 SLEEP wait period SLEEP 4 57 SLEEP truncates decimal values or rounds if compiled with l SLEEP 4 57 causes a 4 second pause or 5 if IEEE Sleeping for a negative amount of time will cause the program to sleep for a very long period 9 45STEP See FOR TO NEXT and STEP above AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 29 9 46STOP The format is STOP Causes the program to suspend execution If you are in interactive mode you may continue to the next statement in sequence by executing a CONT command or a single step command If you are running the program at AMOS command level press to continue or c amp J to end the run 9 47STRSIZ Sets the default value for all unmapped string variables which are encountered for the first time after the STRSIZ statement when the program is compiled Note that STRSIZ is a compile time setting all source code lines after the STRSIZ line are affected Therefore you cannot jump around a STRSIZ statement at runtime by using GOTO commands The forma
257. is BP That is if you don t add an extension to the filename COMPLP looks for a file with that name and a BP extension You then see a number of statistics on your terminal as it compiles your program COMPLP tells you if any errors exist within your source program as it processes your file COMPLP LIT RUNP LIT COMPLP RTI and RUNP RTI may be loaded into system memory or into your user memory partition The fastest access if multiple people use AlphaBASIC PLUS on your computer is if you load them into system memory See the LOAD and SYSTEM command reference sheets in your System Commands Reference Manual COMPLP uses memory in your user memory partition to process your program If there is not enough memory in your partition for COMPLP to complete its task you see an error message and COMPLP returns your terminal to monitor command level If this occurs you may want to remove files loaded into your partition see the DEL command reference sheet in your System Commands Reference Manual f there are no programs loaded into memory or deleting files does not help see your System Operator about increasing the size of your memory partition When COMPLP has finished processing your file it returns you to monitor level and if there are no syntax errors writes the object program to the disk as a file with the name of your source program and an RP extension in this case PAYROL RP If there are errors displayed no RP file is created The r
258. ition is fulfilled Write protected Your program tried to write to a write protected device Before running the program again turn off the device s write protection Wrong number of subscripts The number of subscripts specified is not the same as the number defined for the subscripted variable Check your code Setting size of string work area below calculated For setting size of string work area below calculated COMPLP calculated the required size of the string work area based on worst case conditions You have used a PRAGMA to set the size below this calculated value COMPLP is just warning you of this pragma option on line number overridden by compiler switch pragma option on line number overridden by compiler switch You have specified a COMPLP command line switch which matches a PRAGMA option in the source code The command line switch takes precedence and overrides the PRAGMA setting COMPLP is warning you of this AlphaBASIC PLUS User s Manual Rev 02 APPENDIX B RESERVED WORDS Below is a list of the reserved words used by the BASIC compiler Some of these reserved words may designate routines that have not been implemented at this time However you must not use ANY of these reserved words as variable names This restriction applies to string variables as well as numeric variables i e END and END are both illegal variable names ABS ACS ALLOCATE ALLOCATE INDEXED AMOS AND APPEND ASC ASN ATN BASICP
259. ive record number to be released AlphaBASIC PLUS User s Manual Rev 03 Using ISAM PLUS Files Page 19 7 The default record number is the record last accessed successfully from the file using GET or FIND Releasing an unlocked record is NOT an error All errors are trapped 19 3 10RELEASE ALL This call releases all the locked records The format is RELEASE ALL file channel RELEASE ALL normally does not produce errors Any error status returned by ISAMP are trapped 19 3 11CLOSE You must close all ISAM PLUS files opened for processing The format is CLOSE file channel file channel is the number assigned to the file by a previous OPEN 19 3 12CLOSEK Closes the ISAM PLUS file but keeps it locked so the next program in the process can access it The format is CLOSEK file channel The file channel is the number assigned to the file by a previous OPEN If the program was not locked when OPENed no lock is maintained Be sure your program unlocks the file when done 19 3 13UNLOKR This statement is used to explicitly unlock the last successfully accessed record This statement is functionally equivalent to a RELEASE RECORD file channel statement and has been included for compatibility reasons The format is UNLOKR file channel file channel is the number assigned to the file by a previous OPEN AlphaBASIC PLUS User s Manual Rev 03 Page 19 8 Chapter Nineteen 19 4CREATING AN ISAM PLUS
260. l 0 is defined as your terminal You can use this in sequential file statements to write to your terminal at run time if you wish Random files cannot use file channel zero For example when you first create a file you assign it a file channel number say 1 Then whenever you refer to that file you use that number to tell AlphaBASIC PLUS which file you are talking about say READ 1 This allows you to have many files ready for use at the same time Once you close a file the file channel is no longer associated with it and you may open another file on that file channel You may never have two files open at the same time having the same file channel number The file channel always follows the verb such as OPEN in any file input output statement and may be any numeric expression which is preceded by a pound sign For example OPEN 1 PAYROL DAT INPUT or OPEN file channel num PAYROL DAT INPUT or OPEN number needed num in stock INVEN DAT OUTPUT Up to 256 files may be open at one time in a program 15 3INPUT OUTPUT STATEMENTS The following table shows the AlphaBASIC PLUS program statements you use to input and output data to and from files ACTION RANDOM SEQUENTIAL Read Data READ READ READ ONLY INPUT INPUT LINE INPUT RAW Read and Lock READL Write Data WRITE WRITEN PRINT Write and Lock WRITEL WRITELN AlphaBASIC PLUS User s Manual Rev 02
261. le can A floating point variable may return 0 0 File not found 0 5 File has zero blocks Usually this signifies that the file has been opened for output by any user on the system Positive n gt 1 0 File found The file is a sequential file and contains n disk blocks n lt 0 0 File found The file is a contiguous random file and contains n disk blocks A binary or integer variable cannot hold a value of 0 5 Therefore coding with a binary or integer variable will not allow distinguishing between a file that does not exist and a file that has zero blocks which may be open for output Further using a binary variable will cause an unexpected result for contiguous files binary variables are by definition unsigned and so cannot hold negative values If a negative value is stored in a binary value it will be held as a very large positive value the sign bit is ignored and is presumed to be a high order bit value For this reason it is recommended that a binary variable is not used to record the result of a LOOKUP statement Therefore an integer variable may return 0 File not found or file has zero blocks Positive n gt 1 File found The file is a sequential file and contains n disk blocks n 1 File found The file is a contiguous random file and contains n disk blocks A binary variable may return 0 File not found or file has zero blocks n File found Impossible to distinguish between sequential file and a contig
262. letely separate source file usually one with a BP extension with just one subprogram to a file In this case the file is compiled separately from other source files producing a subprogram object code file with a SPG extension Such subprograms are termed external subprograms 16 2 2 1Considerations for Internal Subprograms Although the runtime environment of an internal subprogram is separate from the main program the compile time environment is not This has a number of consequences eLine numbers in internal subprograms must be unique in the entire source file eAny command line switches affect the subprograms as well as the main program eA PRAGMA setting takes effect immediately and is in force for the rest of the source file including across subprograms eOnly SCALE and the string work area size settings are reset to their default on starting a subprogram compilation Other settings such as STRSIZ are not changed and so affect subsequent subprograms Runtime settings such as SCALE are discussed in a later section The recommended practice is to explicitly set each compiler directive in each subprogram This bulletproofs you from future changes in AlphaBASIC PLUS and prevents an internal program executing differently if it is converted to an external program and hence compiled separately by a simple cut and paste editing operation 16 2 3Subprogram Structure A subprogram is delineated by a pair of statements The s
263. ly you use a combination of READL and WRITE to modify a record in the file but if it is a new record you can t use READL because the record does not yet exist Thus to write to the record you want to lock it for exclusive use for protection If you are in RANDOM or INDEXED EXCLUSIVE mode WRITEL functions exactly like WRITE The format is WRITEL ffile channel variable 15 9 19WRITEN WRITEN is a special form of the WRITE statement allowing you to write to a record without releasing the lock after you finish This lets you later write to that record without a wait The format is WRITEN ffile channel variable m Be careful your program writes to the record again or otherwise releases the lock 15 9 20WRITELN WRITELN is a special form of the WRITEL statement allowing you to write to a record without releasing the lock after you finish This lets you later write to that record without a wait The format is WRITELN file channel variable m Be careful your program writes to the record again or otherwise releases the lock AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 16 CHAINING AND SUBPROGRAMS This chapter discusses eThe CHAIN statement eCHAINing to other programs eCHAINing to System Functions eWhat a Subprogram is eUsing a Subprogram eVariables in Subprograms 16 1THE CHAIN STATEMENT The CHAIN statement stops the run of the current program and causes another program or system functi
264. m at AMOS level with RUNP Source line overflow A line in the source program including continuation lines exceeds 500 characters Check your code for the excessive line and see if you can break it into multiple statements or reduce its length Stack overflow This may be caused by nesting GOSUBs too deep or branching out of FOR NEXT loops Check your code or increase the STACK value in your BPR file See Appendix H for details String work area exceeded RUNP requires more string work area than COMPLP assigned You need to adjust the size of the string work area by using PRAGMA commands as explained in Appendix I SUBPROGRAM name must be of string type Change the name to a string Subprogram name too large or null Adjust the name Subroutine not found The specified subroutine could not be found Check your spelling and your directory Subscript out of range The specified subscript is outside the range specified in the DIM or MAP statement for the subscripted variable Check your subscript variable Syntax error The syntax of the specified line is invalid Check your spelling AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 19 System error This is used as a catch all error message indicating AlphaBASIC PLUS can t identify the exact problem during the execution of the specified line For example if AlphaBASIC PLUS encounters a Buffer not INITed error message it displays System error because it does
265. mbers with GOTO and GOSUB statements and makes the program easier to document Here is a program that uses labels START PROGRAM INPUT Enter two numbers to get the sum A B PRINT A B A B IF A B lt gt 0 GOTO Sum_not_Zero RINT The sum is zero OTO END PROGRAM Sum_not_zero PRINT The sum is not zero END PROGRAM END Q tU where START PROGRAM Sum not Zero and END PROGRAM are labels Note a reference to a label such as GOTO END PROGRAM does not have to be terminated by a colon The reference must be identical to the actual label in its case upper and or lower and in the placement of delimiters For example GOTO ENDPROGRAM or GOTO End Program causes an error message when referring to END PROGRAM For more information on GOTO see Chapter 9 You may use AlphaBASIC PLUS reserved words as labels END REM etc 2 3COMMENTS REM AND AlphaBASIC PLUS allows you to insert comments into your source program in two different ways The keyword REM may appear alone on a line followed by the comment or may be inserted on the same line as a statement to comment on the purpose of the statement You may follow the REM or remarks keyword with anything you want For example AlphaBASIC PLUS User s Manual Rev 02 General Information Page 2 3 REM ANYTHING YOU WISH TO SAY PRINT A REM gt VARIABLE A MEANS ALLOWANCE
266. me Format 1 4 The Time Time Format TIME 1 PRINT Hours Minutes Seconds You can use a similar program to time processes using seconds minutes or hours as a differential See Chapter 14 for using the symbol within MAP statements 11 6LOOKUP The LOOKUP function looks for a file on the disk and returns a value which tells you if the file is found and if so how many disk blocks it contains The format is LOOKUP filespec where filespec is any string expression which evaluates to a legal file description the default extension is DAT The file specification can be up to 48 characters in length AlphaBASIC PLUS User s Manual Rev 04 System and File Functions Page 11 5 The result can be placed in any legal floating point variable The returned value may be 0 0 File not found 0 5 File has zero blocks Usually this signifies that the file has been opened for output by any user on the system n gt 1 0 File found The file is a sequential file and contains n disk blocks n lt 0 0 File found The file is a contiguous random file and contains n disk blocks For example IF LOOKUP TEST DAT 0 THEN GOTO CREATE FILE RESULT LOOKUP TEST DAT IF RESULT gt 500 THEN GOTO OPEN NEW FILE You may also use LOOKUP as a keyword see Chapter 15 11 7KILL The KILL function erases a file from the disk and returns a valu
267. ments for many string functions 10 3 10SPACE X Returns a string of X number of blank spaces X must be a positive number The statement READY PRINT COLUMN A PRINT SPACE 10 PRINT COLUMN B QUN COLUMN A COLUMN B where the 10 spaces between the first and second strings are the result of the SPACE 10 function SPACE is especially handy for padding strings to a fixed length For example STRSIZ 25 INPUT Name NAMES IF LEN NAMES 25 amp THEN NAMES NAMES SPACE 25 LEN NAMES You may need to adjust AlphaBASIC PLUS s string work area size if you use SPACE See the Section Setting The String Work Area Size in Chapter 8 for details AlphaBASIC PLUS User s Manual Rev 03 Page 10 10 Chapter Ten 10 3 11STR X Returns a string which is the character representation of the numeric expression X No leading space is returned for positive numbers For example READY AS STR 45 EN PRINT AS EUAN 45 10 3 12STRIP A Returns a copy of an expression having no trailing spaces or tabs The format is STRIPS expression If the expression is numeric it is converted to a string 10 3 13TIME Returns the number of seconds since midnight 10 3 14UCS A Returns a string which is similar to the argument string A except all characters are translated to upper case For example READY STRSIZ 20 EN AS M is for Micro ETA PR
268. n If you try to save a file when there is no source program in memory AlphaBASIC PLUS displays No source program in text buffer If a previous version of the program one with the same name already exists on the disk in the account you are writing the file to that program is first deleted before the new program is saved AlphaBASIC PLUS doesn t automatically create a backup file so be careful when choosing a name for a program You can use the LOOKUP command as an interactive direct statement to see if the file exists on the disk For example LOOKUP TEST RP result PRINT result If the number printed is not zero the file exists See Chapter 15 for more information on LOOKUP The resulting object program RP file is re usable and re entrant it may be loaded into system memory so everyone on your system can use the program even at the same time In the interests of security AlphaBASIC PLUS doesn t let you save a program in an account not within the same project as the account you are logged into For example if you are logged into DSK2 100 2 and you try to save a program in DSK2 340 1 you See Cannot open NEWPRG BP 340 1 protection violation Since AlphaBASIC PLUS cannot convert an object file back to a source program file you probably want to save the BP version of your program After saving a program from within interactive mode the source program still exists in interactive memory until you use NEW
269. n random files can contain data in any format supported by AlphaBASIC PLUS unlike sequential files which only contain ASCII data Random files like sequential files have a default extension of DAT AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 5 15 5 1Logical Records E All program accesses to random files are made by using the logical record approach A logical record is defined as a fixed number of bytes whose format is explicitly under control of the program performing the access Physical blocks on the disk are each 512 bytes long AlphaBASIC PLUS allows you to choose whether you want to work with records that fit within this structure or if you want to overlap your records over these bounderies If you want to span the 512 byte blocks AlphaBASIC PLUS automatically computes the number of logical records that fit into one disk block and performs the blocking and unblocking functions for you For example if your logical record size is defined as 100 bytes then each block on the disk contains 5 logical records with the last 12 bytes of each block being unused The most efficient use of random files comes when the logical record size is a number that divides evenly into 512 256 128 64 etc 15 5 2Figuring Out How Many Blocks Your File Needs E This section assumes you are not using the SPAN BLOCKS option to disregard physical block sizes Random access files are pre allocated once
270. n be used in RANDOM FORCED or INDEXED modes It locks the record you are reading for your exclusive use If you are in RANDOM or INDEXED EXCLUSIVE mode READL works the same as READ that is it does not lock the record since the file is already locked The format is READL file channel varl Once you lock the record with READL use WRITE to rewrite the record to the file WRITE automatically unlocks the record when it is done If you use READL without later using WRITE you must use the UNLOKR statement to unlock the record 15 9 15READ READ ONLY Unlike READ it allows you to examine data even if another program has the data locked Where READ returns a File Record in use message READ READ ONLY lets you read the data READ READ ONLY is useful if you need the data immediately and if you don t care if the data may be slightly old the program that has the lock may be updating the data as you are reading it You can not update the record and write it back to the file if you use READ READ ONLY AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 21 15 9 16UNLOKR UNLOKR allows you to unlock a record locked with a READL statement The format is UNLOKR file channel If you do not use a WRITE statement to unlock records after their use you must use the UNLOKR statement so other users can access those records 15 9 17WRITE The WRITE statement is used to write a selected logical record t
271. n executed AlphaBASIC PLUS User s Manual Rev 02 Mapping Variables Page 14 5 Since these mapped arrays are assigned memory at compile time and not at run time the subscripts must be decimal numbers or constants instead of variables 14 2 3Type The type is a single character code which specifies the type of variable mapped binary unsigned numeric variable floating point variable integer variable true binary signed numeric string variable unformatted absolute data variable xn TU If no type code is entered AlphaBASIC PLUS assumes an unformatted variable Variable types are described in Chapter 6 14 2 3 1Unformatted Data Unformatted variables are used to group together any variables mapped below them It might help to think of an unformatted variable as the file folder holding all the information stored in the variables below it You usually define an unformatted variable so you can refer to a group of other variables as one unit The contents of unformatted data variables should only be moved to other unformatted data variables In the example above the variables PATIENT INFO NAME and ADDRESS are unformatted variables since nothing is specified they default to unformatted An unformatted variable is like a storage area for all the variables mapped below it in the case of NAME the variables LAST and FIRST This allows these groups of information to be moved as a unit simply by using the unformatted varia
272. n t know how to handle this condition Determine which line of your code is causing the problem and correct it TO expected 2TO or SUB expected Adjust your code so the expected condition is fulfilled 2Too many arguments to function Check the function format and reduce the number of arguments 2Too many errors The compiler reported its limit of errors When you have fixed the ones displayed re compile for possible further messages 2Too many files open There are too many files open at this point The program needs to be modified 2Too many parameters You have passed too many parameters to a system defined or user defined function 2Too many parameters to function You have passed too many parameters to a system defined or user defined function Transfer address out of range Try again using the A switch with COMPLP Translation table not found in memory The required translation table was not found in memory Locate it load it into system or user memory and rerun the program Unable to find INCLUDE file filespec Make sure you used the correct name or make sure the proper file exists or is created AlphaBASIC PLUS User s Manual Rev 02 Page A 20 Appendix A Unbalanced parenthesis You are missing a or a Add the appropriate parenthesis Undefined array in XCALL You have specified an array to an XCALL which has not yet been allocated in memory This means that either 1 the array was not MAPed 2 the array
273. n the computer world A few minutes spent making your source file clear and easy to read may save many hours of work for someone at a later time and helps to minimize errors It is also easier for you because the program is easier to debug and easier to modify later You should practice writing your programs in good program form so your programs are always easy to understand and follow It may take a few extra minutes when writing but it saves much more time over the lifetime of the program Let s look at some examples Which of these program lists is easier to read 11 INPUT INPUT THREE NUMBERS A B C 13 D A B C 3 20 ANSWER D 33 INPUT Do you want to try again ES 40 If ES Y then goto 11 43 END AlphaBASIC PLUS User s Manual Rev 02 Programming Hints Page C 3 or This program takes three numbers as input and averages them MAP1 ANSWER F MAP FIRST F MAP SECOND F MAP THIRD F MAP1 QUERY S 1 NPUT NUMBERS INPUT Input three numbers FIRST SECOND THIRD CALCULATE ANSWER ANSWER FIRST SECOND THIRD 3 PRINT PRINT The average is ANSWER PRINT DO IT AGAIN PRINT Would you like to average INPUT more numbers Y or N QUERY IF UCS QUERY Y THEN GOTO INPUT NUMBERS END
274. n the range 0 65535 lllegal command line Check your syntax and try again Illegal expression The specified expression is not valid Check your syntax and spelling AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 9 lllegal function name Check your syntax and or change the name lllegal function value The specified value is not valid for the particular function See the instructions for that function to see what type and number of arguments it takes and the valid values for its arguments lllegal GOTO or GOSUB The format of the GOTO or GOSUB statement is invalid Check the label or line number it refers to lllegal IF construct Check the format of the IF statement and try again lllegal in immediate mode You cannot use whatever you entered in interactive BASIC only in a program file lllegal ISAM sequence The sequence of commands used for the ISAM file were executed in the wrong order for the File Locking system Illegal key number You have specified an illegal key number one that does not exist in an ISAM PLUS statement lllegal line number number The specified line number is invalid Line numbers must be positive integers less than 65 535 lllegal MAP level Correct the MAP level to a legal number 1 16 lllegal NEXT variable The variable in the NEXT statement is invalid it does not equal the variable in any previous FOR statement Check your variable AlphaBASIC PLUS User s Manual
275. n use AlphaBASIC PLUS in two different ways either as an interactive system interactive mode or as a disk file compiler system Your choice of how you use AlphaBASIC PLUS depends on several factors eThe amount of memory you have in your user partition eWhat stage of development your program is in eThe physical form of your program eThe size of your program eYour personal preference Chapters 3 and 4 tell you more about the Interactive mode and Chapter 5 explains how to use AlphaXED the compiler and the run time package together 1 7EXTENSIONS USED WITH ALPHABASIC PLUS As with all AMOS files your AlphaBASIC PLUS programs can have names made up of from 1 to 6 alphanumeric characters The default file extension for AlphaBASIC PLUS source programs is BP If your source program has this extension you don t need to specify the extension when you compile the program The COMPLP program automatically creates a file with the same name as your source file but with a RP extension This extension is the default for the RUNP program Other extensions you may use with AlphaBASIC PLUS include BPI an include file SPG a compiled external subprogram and XBR an assembly language subroutine These are discussed later in this manual 1 8WHAT DOES AN ALPHABASIC PLUS PROGRAM LOOK LIKE Here is a small sample program written in AlphaBASIC PLUS RINT Hello INPUT Type in a number you would like squared NUMBER ANSWER NUMBER N
276. named subroutine is located in memory and then called 18 2AUTOMATIC SUBROUTINE LOADING When an AlphaBASIC PLUS program calls a subroutine by using an XCALL statement AlphaBASIC PLUS attempts to locate the subroutine in user or system memory If it cannot it attempts to load the subroutine from the disk following the search pattern outlined in Chapter 2 If an AlphaBASIC PLUS program fetches a subroutine from the disk AlphaBASIC PLUS loads the subroutine into memory only for the duration of its execution The subroutine is loaded as a standard AMOS module in the area reserved by MINF at the top of your memory partition See Appendix H for details Once the subroutine has completed its execution it is removed from memory Therefore if a subroutine is to be called a large number of times it is wise to load it into memory using the monitor LOAD command to avoid the overhead of fetching the subroutine from disk m Subroutines loaded into memory by use of the monitor LOAD command remain in memory until you reset the system or until you use the monitor command DEL to delete them AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 19 USING ISAM PLUS FILES This chapter is a quick reference guide to using ISAM PLUS from AlphaBASIC PLUS and discusses eWhat ISAM PLUS is eThe ISAM PLUS file structure eUpdating ISAM PLUS files eCreating an ISAM PLUS file eRetrieving statistics of an ISAM PLUS file eError processing 19 1WHAT IS
277. nction or a command file from an AlphaBASIC PLUS program If the extension of the file in the CHAIN statement is not RP AlphaBASIC PLUS assumes the file is a system command program or system command file a LIT DO or CMD file In this case the AlphaBASIC PLUS run time package creates a dummy command file at the top of the current user partition and transfers control to the monitor command processor AlphaBASIC PLUS User s Manual Rev 02 Chaining and Subprograms Page 16 3 The monitor then interprets this dummy command file as a direct command and executes it Note the dummy command file created by the run time package is merely the one line name specified in the CHAIN statement It is not the command file being chained to itself which is the target function desired You can also include parameters for that program or command file Some valid examples are CHAIN TEST1 CMD CHAIN DSKO BACKUP CMD 2 2 CHAIN SEE DO 110 0 MEMO TXT Note that if you CHAIN to RUNP to execute another RP file the existing instance of RUNP will commit suicide by executing an EXIT monitor call after performing END processing A new instance of RUNP will be initialized This has the side effect of deleting all temporary memory modules in the user s position and causing the target RP and BPR file to be read and processed If the device and account are not specified the search path is 1System memory 2User memory 3 The account
278. nd then run under a version of RUNP that does not have compatibility option functionality that is a version earlier than 1 0 267 the file will be executed without complaint All selected options are irrelevant to such a version of RUNP Therefore if you run a program compiled under COMPLP 10 0 600 with the ABC option set RUNP 1 0 250 will execute it ignoring the option setting Rule 5 lIf you CHAIN to another program that program is independent of the exiting program The chaining program does not hand on any compatability option requirements to the chainee RUNP will check the chained to program s header and determine if it can execute the chained to program as it loads the file If it cannot execute the file RUNP will fail with a non trappable error If you build PROG1 RP with COMPLP 10 0 606 with the ABC option selected and that CHAINs to PROG2 RP built with COMPLP 10 0 606 with the ABC and XYZ options slected all is well if PROG1 RP is run under RUNP 10 0 606 If you use RUNP 10 0 600 PROG1 RP will execute and start CHAINing to PROG2 RP But PROG2 RP will not execute as option XYZ is not understood by RUNP 10 0 600 and it will abort with a non trappable error eRule 6 If you make a SUBCALL to a subprogram that s internal to your main RP file that subprogram will execute using the selected options However a separately compiled subprogram is an entity completely isolated from the calling RP or SPG program The calli
279. ndix J for option values and definitions Once selected an option cannot be deselected WIN Any PRAGMA options set in a INCLUDEd file will be active on return to the 3 program that contained the 4 INCLUDE statement Each of the above PRAGMA settings except for FEATURE takes a single parameter to tell the compiler to either turn the option on or off The following case insensitive values are recognized To turn the option on ON 1 TRUE Yes string and Yes character make it active each within double quotes defined in the LDF file of the job doing the compilation To turn the option off OFF 0 FALSE No string and No character make it inactive each within double quotes defined in the LDF file of the job doing the compilation PRAGMA settings take effect immediately and last for the rest of the source file including any subprograms see Chapter 16 defined in the file If you specify both a PRAGMA setting and its corresponding command line switch at compile time the command line switch will override any and all corresponding PRAGMA commands This allows a default condition to be set up in the source file which can be overridden on an as needed basis by the command line 5 4 3 2Setting String Work Area Size The string work area is a runtime memory allocation which is used by RUNP s string processing The size of this area can be set automatically by the compiler but there are occasions where you nee
280. ned in the OPEN statement 15 9 11 10PEN Modes The mode specifies how the file is to be OPENed INPUT Opens an existing sequential file for input operations File Lock access shared OUTPUT Opens an existing sequential file for output operations File Lock access exclusive Will create the file APPEND Opens an existing sequential file so you can add data to the end of the file Creates the file if it doesn t exist Access is exclusive RANDOM Opens an existing random file for random read write Access is exclusive RANDOM FORCED Opens an existing random file for random read write Access is shared INDEXED Opens ISAM or ISAM PLUS data and primary index file Access is shared See note below INDEXED EXCLUSIVE Opens ISAM or ISAM PLUS data and primary index file Access is exclusive ISAM INDEXED Same as INDEXED for ISAM only ISAM INDEXED EXCLUSIVE ISAMP INDEXED ISAMP INDEXED EXCLUSIVE Same as INDEXED EXCLUSIVE for ISAM only Same as INDEXED for ISAM PLUS only Same as INDEXED EXCLUSIVE for ISAM PLUS only AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 19 INDEXED and INDEXED EXCLUSIVE normally open ISAM PLUS files If you use the X switch at compile time they open ISAM files instead ISAMP INDEXED EXCLUSIVE and ISAMP INDEXED always open files as ISAM PLUS files whether X is used during compilation or not Similarly ISAM INDEXED and ISAM INDEXED INCLUSIVE always open files
281. ng The format string must begin with one symbol followed by a series of Zs The total size of the formatted string is the number of Zs plus the one symbol For example READY PRINT 123 USING 22222 EUR 000123 12 2 9Add a Trailing Minus Sign to a Number You may cause the sign of a number to be printed following the number by ending a numeric field in a format string with a minus sign If the number is positive AlphaBASIC PLUS prints a blank after the number if it is negative AlphaBASIC PLUS prints a minus sign after the number For example AlphaBASIC PLUS User s Manual Rev 02 Page 12 8 Chapter Twelve READY MAP1 MASK S 26 V 7 N SSHHH HH H REUN C Credit REUN D Debit REUN PRINT USING MASK C 35 67 D 57 89 C 10 89 D 356 33 ET Credit 35 67 Debit 57 89 Credit 10 89 Debit 356 33 12 2 10Printing Numbers as Exponents 4444 You may specify exponential format by following the numeric field in a format string with four carets These define the spaces taken up by the E nn exponent characters AlphaBASIC PLUS left justifies the significant digits adjusting the exponent as necessary As with other numeric formats AlphaBASIC PLUS allows any decimal point arrangement For example READY PRINT USING 100 2345 66 5000 0004 ey 10000E 03 23457E 04 50000E 04 40000E 03 12 3FORMATTING EXAMPLES AND HINTS All of our examples
282. ng AlphaVUE When a local variable hides the value of a global variable This can occur in AlphaBASIC PLUS inside a function defintion If you have a FORMAL PARAMETER with the same variable name as a variable in your main program the value of that variable is different within the function than in the main program While in the function definition the formal parameter variable has the value assigned to it in the definition When the definition is finished the variable again has the value assigned to it in the main program AlphaBASIC PLUS User s Manual Rev 02 Page 8 SIGNIFICANCE SOURCE SPOOLING STRING STRING LITERAL SUBROUTINE SUBSCRIPTS SUBSTRING SWITCH SYSTEM MEMORY Glossary How many digits are used to represent a number Normally numbers are given in 6 digit significance but can be set from 1 to 15 by the SIGNIFICANCE statement A file containing the original text or code In AlphaBASIC PLUS the source file is the file containing the AlphaBASIC PLUS code the file usually has a BP extension Sending a file to a printer queue so it can await printing An ASCII character or a group of ASCII characters ASCII characters include letters numbers punctuation marks and special symbols see Appendix C for a complete list A string enclosed in quotation marks to indicate it is as it appears as opposed to being a variable For example This is a literal string of characters A section o
283. ng program does not hand on its compatibility AlphaBASIC PLUS User s Manual Rev 03 Compiler and Runtime Options Page J 5 option requirements to its callee As it loads the called program RUNP will check the callee s header and determine if it can execute it If not it will fail with a non trappable error Always minimize the number of compatibility options you specify at compile time because that allows the executable file to run under more versions of RUNP To assist with this COMPLP 1 0 269 2 and later will make reasonable efforts to tell you if a compatibility option was invoked but never triggered in the source lines For example assume the ABC option was something to do with the SIGNIFICANCE statement If you specified the ABC option but never wrote a SIGNIFICANCE statement in the file you have probably specified an option in error and COMPLP will warn you about it J 6DEFINED OPTIONS Number First Added Description 1 1 0 269 2 If set DELETE RECORD maintains the functionality of versions before 1 0 269 2 The only error reported is Record Not Locked and for that error you have to inspect the file s status variable to see if the error occurred If this option is not set DELETE RECORD can report the full set of errors setting the file status variable and throwing a standard AlphaBASIC PLUS trappable error This new behavior the default from version 1 0 269 2 onwards may break programs that do not expect DELETE REC
284. ng the value of zero The format of each 10 byte block describing one argument is Entry 1 One word containing a variable type code Bits 0 3 contain the type code for the specific variable unformatted string AMOS floating point binary integer IEEE floating point O0 A BNO 1 All other values are currently unassigned Other bits in the type code word are meaningless Entry 2 One longword containing an absolute address of a variable in a user impure area This address is the first byte of the variable no matter its type or size Entry 3 One longword containing the size of the variable in bytes Note the above descriptions also apply to the expression arguments except that the results are located above the address specified by A5 instead of below it The argument list is built in free memory directly above the currently allocated user impure area A4 points to the word immediately following the last word in the argument list You may scan the argument list and determine its end either by decrementing the count word at the base of the list or by scanning until the scan index reaches the address in A4 E 3CONVERTING ARGUMENTS TO BINARY FORMAT A standard subroutine GTARG is provided in the system subroutine library SYSLIB LIB to assist in converting floating point and string arguments to binary format for processing within an AlphaBASIC PLUS subroutine For further information see your AMOS Monitor Calls M
285. ning your own functions is a feature of AlphaBASIC PLUS that can be very useful in your programs It can save space and time by replacing repetitive sections of code and it can help you organize and clarify your programs The object of a defined function is to write a section of program to do a task your program must do a number of times Once defined the instructions in that defined section of code can be done by just plugging in the function name User definable functions allow you to return a value in an expression where a GOSUB routine does not 20 2SINGLE LINE FUNCTIONS The format is DEF FN name formal parameter 1list expression The name of the function must begin with FN or FN and contain valid variable name characters The formal parameter list is a list of variables separated by commas which indicate the formal parameters to the function The expression is what computes the value of the function For example AlphaBASIC PLUS User s Manual Rev 02 Page 20 2 Chapter Twenty Jg EF FN Multiply a b a b INPUT Input a number Number Input INPUT Input a number to multiply it by Multiplier Answer FN Multiply Number Input Multiplier PRINT The answer is Answer The above example defines a function to multiply two numbers together When the function name is used the variables in this case Number Input and Multiplier are plugged into the equation defined in the function
286. not based on a fixed beginning value set by the system If you want to generate a random number greater than or equal to number A and less than number B use the expression B A RND 0 A The INT function can be used when generating random integer numbers to give you an integer number For example to generate a random integer greater than or equal to 5 and less than 31 use the expression INT 26 RND 0 5 B A 26 AlphaBASIC PLUS User s Manual Rev 03 Page 10 4 Chapter Ten 10 1 10RNDN X Returns the result of rounding the number to the nearest integer Numbers with a decimal fraction of 0 5 or larger are rounded to the next higher integer in absolute value those with a smaller decimal fraction are rounded down For example READY PRINT RNDN 50 4685 i RNDN 50 876 REUN ae RNDN 50 486 Pune RNDN 750 876 51 10 1 11SGN X Tells you the sign of the number X If X is a negative number SGN X generates a 1 If X is 0 SGN X is O If X is a positive number SGN X is 1 10 1 12SQR X Returns the square root of the argument X The square root is the number when multiplied by itself gives you X For example READY PRINT SQR 25 5 10 1 13VAL A Returns the numeric value of the string variable or literal A converted to floating point under normal AlphaBASIC PLUS format rules For example VAL 13 returns 13 10 2TRIGONOMETRIC FUNCTIONS The following trigonometric fun
287. nt is reasonably easy to predict for a given RES and MEM configuration As you know which modules are already loaded and which AMOS calls are made setting the size of this area is straightforward The STACK requirement is most heavily affected by the level of nesting of control structures The default is a reasonable number Increase it if you have deeply nested structures The MINS and MAXS factors are the hardest to predict especially as it is not possible to do memory compaction within the Heap of any C program The Heap can therefore get fragmented and the degree of fragmentation can be heavily dependent on the order of statement execution You can use the MEM function to probe some of the Heap and Stack allocations but it is more of an art than a science H 2 6COMPLP and RUNP C Settings You can also set the same parameters for interactive AlohaBASIC PLUS by including them in a file called BASICP PRM in the account you want to run your program in You can create a file called COMPLP PRM for the COMPLP program itself that defines the MAXS MINS and MINF parameters The default for MINF with COMPLP is 4096 all the other defaults are the same as above AlphaBASIC PLUS User s Manual Rev 02 APPENDIX THE STRING WORK AREA AlphaBASIC PLUS allocates memory in the Heap see Appendix H for a work area in which to do string operations such as concatentation substring operations and printing variables This area is known
288. nual Rev 02 Program Statements Page 9 31 0 2 statements CASE CASE Cl FI Matches on 0 or 2 only 9 49THEN See IF THEN and ELSE above 9 50TO See FOR TO NEXT and STEP above 9 51 UNTIL See DO UNTIL above 9 52USING See PRINT USING above 9 53WHILE See DO WHILE above 9 54XCALL The format is XCALL routine argument s Executes an external assembly language subroutine Assembly language subroutines are discussed in detail in Chapter 18 For information on the assembly language subroutines available for use with AlphaBASIC PLUS programs see your AlphaBASIC XCALL Subroutine User s Manual AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 10 FUNCTIONS Functions compute and return a value A function either operates on or is controlled by the argument which is enclosed in parentheses This chapter discusses these types of functions eNumeric eTrigonometric eString eMiscellaneous Functions are different from program statements in that they return a value In order to see or use that value you must include the function in a program statement that evaluates the expression the function call is a part of For example SQR 16 doesn t display a value You must either assign the value returned by the function to a variable or display the value using a PRINT statement if you want to use or see the value returned For example ROOT SOR 16 RESULT ROOT SOR NUMBER 24
289. o an open random file The logical record which is transferred is the one whose record number corresponds to the current value of the record number variable WRITE automatically unlocks the record after it is done if you are sharing the file RANDOM FORCED or INDEXED modes The format of the WRITE statement is WRITE ffile channel variable For example if your OPEN statement is OPEN 1 STOCK DAT OUTPUT rec size rec num and your WRITE statement is WRITE 41 PART NUMBER then the data in PART NUMBER is written to the record that corresponds to the variable rec numin the file STOCK DAT The variable in the WRITE statement list may be in any format but it should match the designated record format The data is written into the logical record from the user variables as unformatted bytes without regard to variable type If the record is longer than the variable list specifies all excess data in the record is not modified If you try to transfer more data than is in the logical record size you get an error message The most efficient use of random files comes when the variable or variables used are mapped by a MAP statement to the exact picture of the record format in use AlphaBASIC PLUS User s Manual Rev 02 Page 15 22 Chapter Fifteen 15 9 18WRITEL WRITEL is a special form of the WRITE statement allowing you to write a new record if you are in RANDOM FORCED or INDEXED modes Normal
290. o changes to the source code are made You can retrieve the compiler version number and time stamp information using the VER function Changes the default XCALL extension from XBR to SBR This is for compatibility purposes for systems running both AlphaBASIC and AlphaBASIC PLUS It lets you place one XCALL subroutine in memory which can be called by both AlphaBASIC and AlphaBASIC PLUS programs Displays each line of your source program as it scans it If a problem occurs during compilation T shows you the line where the problem occurs You can also use T to see how fast different statements compile Program uses traditional ISAM not ISAM PLUS Displays command line usage for COMPLP AlphaBASIC PLUS User s Manual Rev 03 Page 5 6 5 4COMPILATION CONTROL Chapter Five AlphaBASIC PLUS has a number of commands that begin with These commands let you control how your program compiles COMPLP supports all the following commands while BASICP supports only the INCLUDE command The commands are INCLUDE file option ERROR string IF constant expression ELSE ELIF ENDIF lIFDEF variable IFNDEF symbol MESSAGE string PRAGMA setting value Brings another program into the program at the point of the command See the section Including Other Files in Your Program below for details Causes a compilation error to print and the compilation to stop This is useful if used within an
291. o further for example it has reached an END statement Can t open file BASICP couldn t find the file you tried to load Check your syntax and or your file directory CASE DEFAULT or ENDSWITCH without SWITCH Add a SWITCH statement Channel expected Adjust your code so the expected condition is fulfilled Channel number in use Use a different file channel number Channel 0 is illegal for random files You may not specify file channel 40 when accessing a random file Change the file channel number to a positive integer or use a sequential file channel 40 equals your terminal if you are using sequential files Character translation table not found The file you specified in COMPLP s command line cannot be located COMPLP does not support the requested P option You specified an option number that this version of COMPLP does not support Use a later version of COMPLP Constant definition buffer overflow definition ignored You have specified one or more constants on COMPLP s command line but the length of COMPLP s internal buffer for storage is too small for all of the definition s Reduce the size and or the number of definitions A space takes up one byte of internal buffer storage AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 5 Constant expected Adjust your code so the expected condition is fulfilled Copying from program name The program you are compiling contains an INCLUDE command This message
292. o glance through sections 2 through 4 to familiarize yourself with the syntax and features of AlphaBASIC PLUS As you program you will probably find the AlphaBASIC PLUS Quick Reference Card to be helpful to remind you of commands and syntax AlphaBASIC PLUS User s Manual Rev 02 Page 1 2 Chapter One If you are new to or relatively inexperienced with the BASIC language you should read Part before beginning to use AlphaBASIC PLUS You may also want to read a tutorial on BASIC and or a tutorial about programming concepts 1 2WHAT IS BASIC The acronym BASIC stands for Beginners All purpose Symbolic Instruction Code BASIC is a higher level programming language created to be a versatile tool for learning computer programming and also to provide a relatively simple language for a wide variety of applications But today BASIC is more than that Most programming on small interactive systems is done in BASIC One of the reasons is BASIC is so much like the English language Over the years since its inception BASIC has been added to and modified as new concepts of programming have emerged Some versions of BASIC are more extensive than others the use of extended versions provides the programmer with a wider range of applications greater ease in programming and greater efficiency and speed 1 3HOW IS ALPHABASIC PLUS SPECIAL AlphaBASIC PLUS is an extended version of the BASIC language with several features not found in other BASIC impl
293. o makes it easy to quickly test a program by altering lines or data within the program Using disk files the compiler and a run time package is more useful for programs which are to be put into production use or for testing programs which are too large to fit in memory in the interactive mode Using AlphaBASIC PLUS in this way you create the program file using the AlphaXED or AlphaVUE program editor or use a disk file saved from an interactive mode session then you compile the program at monitor level using the COMPLP program Finally you use the run time package the RUNP program to execute the program One of the advantages of using AlphaBASIC PLUS in this way is AlphaXED makes it easy to write and edit your program See Chapter 5 for more information about creating and editing programs with AlphaXED During the actual running of the compiled program only the object code and the run time execution package are in memory This conserves memory on the computer The compiler and the run time package are both written as re entrant programs This means that in a timesharing environment any or all users who are running or debugging programs may share one copy of the compiler and the run time package The way to do this is to load COMPLP LIT the compiler program and RUNP LIT the run time package into system memory optionally along with the files COMPLP RTI and RUNP RTI See your System Operators Guide for information on loading files
294. ogical record locking is done That is when a logical record is locked there is no impact on the ability of another user to access the file or lock different logical records even in the same physical record each physical record can contain more than one logical record Variables used to hold status conditions returned by ISAMP are defined in the file BP ISAMP BPI Your programs should have a INCLUDE ISAMP statement to include this definition file AlphaBASIC PLUS User s Manual Rev 03 Using ISAM PLUS Files Page 19 3 19 3 10PEN Statement for ISAM PLUS Files The OPEN statement opens a pair of ISAM PLUS files for processing The format is OPEN ffile channel filespec mode relrecno filstat END FILE WAIT RECORD WAIT FILE READ ONLY where filstat is a floating point variable that holds the resulting status condition and END FILE opens the file with the file pointer positioned past the last record based on the primary key When used with GET PREV it allows reverse scanning of an indexed file The other options are the same as explained in Chapter 15 The three optional parameters may be specified in any order The mode must be INDEXED INDEXED EXCLUSIVE ISAM INDEXED ISAM INDEXED EXCLUSIVE ISAMP INDEXED OR ISAMP INDEXED EXCLUSIVE To use ISAM instead of ISAM PLUS use ISAM INDEXED or ISAM INDEXED EXCLUSIVE or use the X switch
295. oll box down one line Select jump scroll Select fast smooth scroll Select medium fast smooth scroll Select medium slow smooth scroll Select slow smooth scroll Start underscored blinking field End underscored blinking field Start underscored reverse field End underscored reverse field Start underscored reverse blinking field End underscored reverse blinking field Start underscored text without space End underscored text without space Start reverse text without space End reverse text without space Start reverse blinking text without space End reverse blinking text without space Start underscored blinking text without space End underscored blinking text without space Start underscored reverse text without space End underscored reverse text without space AlphaBASIC PLUS User s Manual Rev 02 Page D 4 TCRT CODE 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 Appendix D FUNCTION Start underscored reverse blinking text without space End underscored reverse blinking text without space Start blink without space End blink without space Set cursor to blinking block Set cursor to steady block Set cursor to blinking underline Set cursor to steady underline Reserved Reserved Reserved Reserved Select
296. ompile time expression that must evaluate to a value between 2MB ytes and 2MB ytes The syntax of the expression must follow that for the DEFINE statement in Chapter 9 AlphaBASIC PLUS User s Manual Rev 02 Page l 2 Appendix I As COMPLP processes each source line it estimates the size of the SWA required to execute the statement It also remembers the largest value encountered so far It is this value that COMPLP would use to set the size of the SWA if no PRAGMAs were encountered Assume that there are four variables COMPLP SWA SIZE STMT SWA SIZE SETSWA SIZE and EXTRA SWA SIZE maintained internally by COMPLP COMPLP manipulates them as follows COMPLP SWA SIZE EXTRA SWA SIZE SET_SWA_SIZE while there s a line to compile STMT SWA SIZE SWA requirement for this line COMPLP SWA SIZE COMPLP SWA SIZE max STMT SWA SIZE end while O OO SET SWA SIZE and EXTRA SWA SIZE can be changed by PRAGMA lines as follows SET_STRWRK SWA SIZE SET_STRWRK value EXTRA SWA SIZE 0 EXTRA STRWRK EXTRA SWA SIZE EXTRA STRWRK value ADD_EXTRA_STRWRK EXTRA SWA SIZE EXTRA SWA SIZE ADD EXTRA STRWRK value At the end of the compilation the SWA size is set if SET SWA SIZE gt 0
297. on definitions the FORMAL PARAMETERS are local to the function definition AlphaBASIC PLUS words that perform tests of logic on expressions Often used in IF THEN statements so the program can do different things depending on how the logic test turns out For example the statement IF NUMBER lt 1 OR NUMBER gt 100 amp THEN GOTO ILLEGAL NUMBER Performs two tests on the variable NUMBER to see if it is less than 1 or greater than 100 The OR is the logical operator and instructs AlphaBASIC PLUS to GOTO ILLEGAL NUMBER if either of the two tests are true A repetition of the same section of code For example FOR I 1 TO 10 PRINT I NEXT I causes PRINT to be executed 10 straight times and each time the variable is incremented by 1 A variable defined at the start of the program by a MAP statement Mapped variables can be grouped into data structures The process of preparing a disk device for use A variable expression with no value For a number the value is zero 0 For a string it s empty quotation marks Any data coming from an AlphaBASIC PLUS program Output is displayed on the terminal or on paper or is placed in a data file AlphaBASIC PLUS User s Manual Rev 02 Glossary PRECEDENCE QUEUE RANDOM RECORD SAVE SCALING SEQUENTIAL SHADOWING Page 7 What comes first In AlphaBASIC PLUS certain expressions could be
298. on the floating point format and certain values involving decimal fractions that are involved with powers of 1 2 e g 1 2 1 4 etc down to a certain value dependent on the format Outside these values only an approximate value is held This is similar to trying to represent the number 1 3 as an exact decimal fraction the number is approximately 0 333 but not exactly 0 33333 is a better approximation and 0 3333333333 is even better but is still not exact This is relevant when you do arithmetic on real numbers because you can get some surprising results Example 1 If you evaluate the expression 10000 3 3 by hand you would get the answer 10000 But in real arithmetic the floating point division yields 3333 3333333 which cannot be held exactly Doing a floating point multiplication by 3 can give say 9999 9999876 as the answer If this result was assigned to an integer the result would be 9999 not the expected 10000 as integer conversion is done by truncation towards minus infinity see Chapter 7 Example 2 Adding small numbers to an already large real number can result in a loss of accuracy For example adding 1 0 to 1 hundred million million a total of one hundred times may result in a result of 1 hundred million million READY 10 SUM 1E14 20 FOR I 1 TO 100 30 SUM SUM 1 0 40 NEXT 50 IF SUM 1E14 PRINT Loss of precision ELSE PRINT OK RUN Loss of precision AlphaBASIC PLUS User s Manual Rev 02
299. on to run The new program to be executed must be named in the CHAIN statement itself that name may be a full file specification The file named in the statement may be another AlphaBASIC PLUS program compiled only or it may be a system command or command file This allows your program to execute a command file and invoke system commands as well as execute other AlphaBASIC PLUS programs 16 1 1Chaining to another AlphaBASIC PLUS Program CHAIN assumes a default extension of RP If you specify another extension AlphaBASIC PLUS assumes you have specified a command file or system command Therefore if you wish to use CHAIN to run another AlphaBASIC PLUS program the file you specify must be compiled and it must have an RP extension AlphaBASIC PLUS User s Manual Rev 02 Page 16 2 Chapter Sixteen IE If you do not specify a device and account AlphaBASIC PLUS follows the search pattern outlined in Chapter 2 when looking for RP files If you do specify a device and account AlphaBASIC PLUS looks in the specified area Note that CHAINing to another RP file will bypass reading and processing of the target BPR file and certain fields of the target s RP files See Appendix H for details All variables in the new program are first cleared to zero prior to the run Some examples of legal CHAIN statements are CHAIN PAYROL CHAIN PAYROL RP CHAIN DSK1 PAYROL 101 13 Due to the fact programs are compiled and not inte
300. onitor Calls Manual contains conversion tables for these constants 6 2 4 3Floating Point Literals Floating point numbers are defined by having either a decimal point or exponent marker or both embedded in the number Examples 12 12 0 1 05766445E24 1 92373D1 23 11 9992 75F 03 127125 234E29 A number with an exponent marker D E or F is interpreted as the decimal fraction multiplied by ten to the power of the number following the marker 1E3 Lew 943 4 345E 05 4 345 10 5 If an F marker is used the type of the number is forced to be AMOS floating point If a D marker is used the number is forced to be an IEEE double precision value Types in either of the two previous cases are not affected by the I COMPLP switch If an E marker is used the type of the value is dependent on the default floating point type IEEE double precision if l is set otherwise AMOS floating point As AlphaBASIC PLUS does not do any operations in IEEE single precision mode there is no marker for single precisions constants Note that the F modifier is a compile time only feature that only works with literals or constant values It will not work with DATA READ or INPUT statements 6 2 4 4String Literals String constants literals are identified by being enclosed in quotation marks For example NAMES Mortimer T Smith The value of NAMES a string variable is set to the string literal Mortimer T Smith
301. ons on the right side of an assignment statement perform an input or read operation and deliver back a result to be used in the expression evaluation 11 1BYTE X WORD X AND LONG X The BYTE WORD and LONG functions let you inspect and alter any memory locations within the memory addressing range of the computer BYTE and WORD are often called PEEK and POKE statements in other versions of BASIC The BYTE function deals with 8 bits of data in the range of 0 to 255 WORD deals with 16 bits of data on an even address boundary which means the X you specify is rounded up to the next even number in the range of 0 to 65535 inclusive and LONG deals with 32 bits of data on an even address boundary rounded up to the next plus one even number Any unused bits are ignored with no error message These commands are not protected it is possible to cause severe damage to the operating system in memory if you use the commands improperly If you don t understand the computer s internal memory addressing we recommend you not use these commands AlphaBASIC PLUS User s Manual Rev 04 Page 11 2 Chapter Eleven BYTE X expr Writes the low byte of lt expr gt to decimal memory location X WORD X expr Writes the low word of lt expr gt to decimal memory location X LONG X expr Write the low longword of lt expr gt to decimal memory location X A BYTE X Reads decimal memory location X and puts the byte in A A WORD X Reads decimal memory
302. ops Loops may be nested to many levels Each time the outermost loop is incremented or decremented once the loop nested within it is executed from beginning to end During the execution of the second loop the third loop if any is fully executed each time the second variable is incremented And so on for each nested loop in the series For example AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 9 DIM MATRIX 5 5 FOR I 1 TO 5 FOR J 1 TO 5 MATRIX I J 1 J Nested loops PRINT MATRIX I J NEXT J PRINT NEXT 1 It is not recommended to branch out of a loop before its completion for example by using a GOTO statement If a loop is not properly ended AlphaBASIC PLUS continues keeping track of the loop control variables in memory these values could cause errors in future calculations in the program Instead exit the loop by using EXIT or by setting control variable to the terminal value given in the FOR statement For example START LOOP FOR I 1 TO 10 INPUT Enter number of pennies Pennies IF Pennies lt 0 amp PRINT You can t have negative pennies EXIT PRINT You have Pennies 100 dollars NEXT I You may use the REPEAT statement to cause the next iteration of the loop without going all the way to the NEXT statement 9 17GOSUB OR CALL AND RETURN The formats are GOSUB label or line number
303. or the next output appears immediately following the last character of the current PRINT statement if the PRINT statement ends with a semicolon Here are a few examples of the PRINT statement AS HERE A 7 What you see PRINT A blank line PRINT A 7 PRINT AS HERE PRINT 1 2 3 PRINT ANY TEXT ANY TEXT PRINT NOTE THE SPACE AS NOTE THE SPACE HERE YOU ARE NUMBER A YOU ARE NUMBER 7 YOU ARE A IN CLASS YOU ARE 7 IN CLASS PRINT THERE ARE Semicolon suppresses CR LF PRINT A DAYS LEFT THERE ARE 7 DAYS LEFT You may also use PRINT for writing data to sequential files see Chapter 15 9 33PRINT USING The formats are variable expression USING format string PRINT USING format string expression list PRINT expression USING format string PRINT USINGi is for formatting output and is described extensively in Chapter 12 AlphaBASIC PLUS User s Manual Rev 02 Page 9 24 Chapter Nine 9 34PROGRAM Lets you specify a revision level for your program The format is PROGRAM Name A B C D where Name A reference name non functional A The major revision number from 0 to 255 B The minor revision number from 0 15 C The revision subscript optional letter from A O D The edit number optional from 0 to 4095 The g
304. orage area using the origin parameter see Chapter 14 However be careful not to forget about the multiple use of the same area AlphaBASIC PLUS User s Manual Rev 02 Page C 2 Appendix C elf you are using line numbers do not assign a line number to lines containing MAP statements or lines having only comments or labels on them eSaving memory is generally good but sometimes using a little extra memory gives you a simpler and easier to maintain program C 2INCREASING EXECUTION SPEED Many of the suggestions in the section above also improve execution speed as well as saving memory Some other hints for improving program execution eUse integer variables in arithmetic operations if possible They are faster than floating point variables Binary variables are slower than floating point so if you can t use integers use floating point eUse the XCALL subroutines if you can rather than writing program code Assembly language routines are faster C 3MAKING YOUR SOURCE PROGRAMS EASIER TO READ One of the considerations you should take into account when you write a program is what happens if somebody else has to update the program Someday someone may have to go into your source file the BP file and make corrections and or additions to it If you are not around to explain your code can that person understand it Can that person find the section he or she needs to work on These questions are becoming increasingly important i
305. orrect now But changing those decisions involves changing the way the compiler and runtime systems work and that may break some existing programs that depend on the current behavior of the products So no changes can be made or so it seems J TRESOLVING THE DILEMMA COMPLP and RUNP version 1 0 267 and later have a feature that can resolve the dilemma At compile time the program developer can specify certain options that cause the compiler and or the runtime system to change their way of operation for that particular file The list of options is processed and acted upon by the compiler and then passed to the runtime system by storing the list inside the object file When RUNP loads the file it reads the option list and alters its actions appropriately Over time the list of options is expected to grow But a given version of COMPLP and RUNP will only understand those options that were defined when they were constructed Later versions may understand more options Part of RUNP s action on loading the file is to check that it can understand and comply with all the requested options If it cannot do so RUNP will abort with a non trappable error J 20PTION SPECIFICATION Options are specified by a number ranging from 1 upwards To request a particular option at compile time type COMPLP filename P optionl option2 For example to select options 1 3 and 6 for MYFILE BP use COMPLP MYFILE P 1 3 6f AlphaBASIC PLUS User s Man
306. ot have a specific size you can OPEN it at whatever size you need Records may by up to 65 535 characters long If you specify a record size you also must use a record variable Record variable A non subscripted numeric variable which must contain the record number of the desired record for READ or WRITE statements when they are executed It must be an integer 6 or 8 byte floating point or 1 4 byte binary variable not a literal number Not used in Sequential files SPAN BLOCKS Optional clause for Random files Allows your records to disregard the 512 byte physical block limit Thus records may be up to 65 535 characters in length and do not need to divide evenly into 512 Files written with SPAN BLOCKS must be read with SPAN BLOCKS and cannot be read by earlier versions of AlphaBASIC that do not support SPAN BLOCKS WAIT FILE Optional clause that causes your program to wait until the specified file is available for use WAIT RECORD Optional clause that causes your program to wait until the specified record is available for use If your program tries to read or write to a file which has not been opened you see an IO to unopened file in line nnn message and the program is aborted If your program tries to read or write to a locked file your program ends and a message is printed informing you the file is in use Of course if you use an error trapping routine you can prevent your program from being aborted READ ON
307. ou may want to save the program on the disk In interactive mode your program is only in temporary memory and it is erased when you leave interactive mode To save a program enter SAVE and a name for the program For example READY SAVE NEWPRG EN READY The command above saves the source program NEWPRG BP as a disk file in the account you are logged into BP is the default extension All program names must be made up of one to six alphanumeric characters All file extensions must be made up of one to three alphanumeric characters Programs are saved as sequential ASCII American Standard Code for Information Interchange files Since this is a standard format you can use the AlphaVUE or AlphaXED text editor to edit your file later If you want to SAVE the program to another account or with a different extension you can specify a full file specification For example READY SAVE NEWPRG SAM 125 3 or AlphaBASIC PLUS User s Manual Rev 02 Page 3 6 Chapter Three E READY SAVE DSK2 PAYROL BP 50 1 You can save the compiled version of that program by specifying the RP extension we discuss compiling programs and RP files later READY SAVE NEWPRG RP If you have not previously compiled the source program or if you have changed the program since the last time you compiled it AlphaBASIC PLUS automatically compiles it for you when you save an RP file to ensure you are saving the most current versio
308. ough it is written on four lines However you may not want to use continuation lines if you want to work on your program in interactive mode Interactive BASICP puts continuation lines back together to form one line Remember also an AlphaBASIC PLUS statement cannot be longer than about 1000 characters even if continuation symbols are used Here is an example of a program using continuation lines indentation and labels and without line numbers STRSIZ 20 Program to print a name in reverse START PRINT INPUT LINE Enter your name NAMES IF LEN NAMES 0 amp THEN GOTO START COUNTER LEN NAMES PRINT LOOP FOR COLUMN COUNTER TO 1 STEP 1 PRINT NAMES COLUMN 1 NEXT PRINT PRINT INPUT Would you like to try another QUERYS IF LCS QUERYS 1 1 y THEN GOTO START amp ELSE PRINT PRINT All done END AlphaBASIC PLUS User s Manual Rev 03 Writing Program Files Page 5 3 5 3COMPILING A PROGRAM Compiling an AlphaBASIC PLUS program is done by using the COMPLP program Compiling a program translates your AlphaBASIC PLUS source program into a language the RUNP program can execute To compile a program make sure you are at AMOS command level then enter COMPLP and the name of your AlphaBASIC PLUS program plus any options you wish For example COMPLP PAYROL EU The default extension
309. our AMOS Terminal System Programmer s Manual See Appendix D for the standard decimal codes in use for the terminal drivers supplied by Alpha Micro AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 13 SCALED ARITHMETIC Whenever a mathematical operation with long decimal numbers is performed the number of significant digits used becomes important AlphaBASIC PLUS uses a floating point format which gives an accuracy of 11 significant digits or 15 if using IEEE format Unfortunately this accuracy is absolute only when dealing with numbers that are total integers with no numbers to the right of the decimal point This is because of the conversions required from ASCII decimal input to the floating point format used to do arithmetic For most business people the range of numbers usually important are those in money format with two digits to the right of the decimal and up to nine digits to the left of the decimal point When the fractional part of the number is converted between decimal and floating point formats a small but significant error is sometimes introduced which may show up when you want to see accurate dollars and cents values As an example in the following statements SIGNIFICANCE 11 PRINT 26 4 INT 26 4 Instead of the expected answer of 4 we see the answer 39999999999 This is NOT an error in AlphaBASIC PLUS but simply represents the side effects of converting a decimal fraction to floating point
310. our calculation Only one subprogram in a subprogram file Place the extra subprogram s in separate files Only one SUBPROGRAM of a main program allowed in BASICP Use only one SUBPROGRAM Operand expected Adjust your code so the expected condition is fulfilled Operator interrupt This message appears when you use Control C to interrupt a program run AlphaBASIC PLUS User s Manual Rev 02 Page A 16 Appendix A Out of data Your program tried to READ data after the data in all of the DATA statements had been used You have to add more data to your DATA statements execute a RESTORE statement or examine your program to determine why it is doing too many READ operations if the amount of your data is correct Out of memory See your System Operator about allocating more memory to your job and or see Appendix C about making your program more memory efficient Appendix H contains details about altering certain RUNP memory allocations Out of memory Compilation aborted COMPLP is telling you it does not have enough free memory to finish compiling your program See your System Operator about allocating more memory to your job and or check your memory partition to see if you have any programs there that can be removed 2PARAMETER statements can only follow SUBPROGRAM statements Place the PARAMETER statement right below the SUBPROGRAM statement PPN not found Your program tried to access a file in a non existent account Check th
311. ped variables are allocated in the fixed storage area while all DYNAMIC arrays are allocated in the array storage area As dynamic arrays are dimensioned their positions may shift relative to one another and relative to the dynamic storage area base Variables in the fixed storage area never change position relative to each other or to the storage area base Array location information given is only pertinent to the base of the array itself which is the location of the first element within the array The actual range of locations used by the array may or may not be contiguous in memory depending on whether overlapped dimensioning techniques are being used in the MAP statements Simple non array variables are defined as a location range which tells exactly where the entire variable lies within the storage area Keep in mind this command is to assist you in following the allocation of variables particularly in more complex mapping schemes A few minutes at the terminal with direct MAP statements followed by commands can help you see how the mapping scheme works 14 6 1Examples Given the sample MAP statements below MAP1 CUSTOMER ID MAP2 NAME MAP3 FIRST S 15 MAP3 LAST S 15 MAP2 ADDRESS MAP3 STREET S 15 MAP3 CITY S 10 MAP3 STATE S 2 MAP2 PHONE MAP3 HOME B 3 MAP3 BUSINESS B 3 MAP2 TRANSACTIONS 12 MAP3 BALANCE F 6 MAP3 CREDIT F 6 MAP3 YTD F
312. piled with D The format is CHAIN filename 22 5 28Break at Subprogram SUBPROGRAM causes the program to execute until the specified SUBPROGRAM call is found This lets you debug a subprogram without having to step through the whole main program Since DB executes all external subprograms up to the specified filename all external subprograms encountered must be compiled with D The format is AlphaBASIC PLUS User s Manual Rev 02 Page 22 10 Chapter Twenty Two SUBPROGRAM filename 22 6DEBUGGING A SUBPROGRAM The RUNP program gives you a way to run a program up to a CHAIN statement and then debugs from that point This means you don t have to compile all the preceeding subprograms as with the CHAIN statement above The format is RUNP D subprogram filename source filename DB runs the source file as RUNP would until the subprogram is encountered then goes into debug mode for the rest of the program The subprogram file and any subsequent subprograms must be compiled with D AlphaBASIC PLUS User s Manual Rev 02 APPENDIX A MESSAGES Below is a complete list of all messages output by the AlphaBASIC PLUS system BASICP RUNP and COMPLP and a brief explanation of each message HHH Your program is using a PRINT USING statement and it could not process the data given it Check the syntax of the line against the rules for PRINT USING in Chapter 11 or expected Adjust your code so the expected condition is f
313. postrophe Quote Opening Parenthesis Closing Parenthesis Minus Sign Period Slash Page F 4 Appendix F Char Also Octal Decimal Hex ISO IEC 10646 1 1993 E Also Known As Type See acter Called Value Value Value and Unicode 2 0 Name Note 111 73 49 Latin Capital Letter Lu J 112 74 4A Latin Capital Letter J Lu K 113 75 4B Latin Capital Letter K Lu L 114 76 4C Latin Capital Letter L Lu M 115 77 4D Latin Capital Letter M Lu N 116 78 4E Latin Capital Letter N Lu O 117 79 4F Latin Capital Letter O Lu P 120 80 50 Latin Capital Letter P Lu Q 121 81 51 Latin Capital Letter Q Lu R 122 82 52 Latin Capital Letter R Lu S 123 83 53 Latin Capital Letter S Lu T 124 84 54 Latin Capital Letter T Lu U 125 85 55 Latin Capital Letter U Lu V 126 86 56 Latin Capital Letter V Lu W 127 87 57 Latin Capital Letter W Lu X 130 88 58 Latin Capital Letter X Lu Y 131 89 59 Latin Capital Letter Y Lu Z 132 90 5A Latin Capital Letter Z Lu 133 91 5B Left Square Bracket Opening Square Bracket Ps 1 134 92 5C Reverse Solidus Backslash Po 1 135 93 5D Right Square Bracket Closing Square Bracket Pe 1 A 136 94 5E Circumflex Accent Spacing Circumflex Caret Lm 1 a 137 95 5F Low Line Spacing Underscore So Underscore 140 96 60 Grave Accent Spacing Grave Lm 1 a 141 97 61 Latin Small Letter A LI b 142 98 62 Latin Small Letter B LI C 143 99 63 Latin Small Letter C LI d 144 100 64 Latin Small Letter D LI e 145 101 65 Latin Small Letter E LI f
314. programs is some tasks are too awkward or even impossible to do from within a higher level language Assembly language programs are uniquely suitable for applications requiring that you work more closely with the hardware or operating system than is convenient or possible in BASIC Although you may want to write your own assembly language subroutines see Appendix E for further information note we do provide a set of existing assembly language subroutines in the AlphaBASIC PLUS Library Account BP DSKO 7 35 These files have an XBR extension For information on these subroutines see your AlphaBASIC XCALL Subroutine User s Manual AlphaBASIC PLUS User s Manual Rev 02 Page 18 2 Chapter Eighteen In addition a set of business oriented assembly language subroutines is available from your Alpha Micro dealer To call an assembly language subroutine from an AlphaBASIC PLUS program use the XCALL statement The syntax for this statement is XCALL routine argumentl argumentN For example XCALL BASORT 3 0 3 0 80 0 XCALLs in AlphaBASIC PLUS assume an integer value unless a number is specified with a decimal point as in the example above If the statement is XCALL BASORT 3 3 80 BASORT uses the numbers as integers The routine to be called is an assembly language program which has been assembled using the machine language assembler When the XCALL statement is executed by the AlphaBASIC PLUS run time system the
315. r MAP1 AMOS Floating point size 6 located at 68 73 22 5 3Set a Breakpoint Creates a breakpoint at a specified label Any time a breakpoint is encountered the program halts and waits for a new command You may have up to 16 breakpoints For example gt break loopl sets a breakpoint at loop1 If you don t enter a label it displays all breakpoints set 22 5 4Clear a Breakpoint Clears a breakpoint For example gt clear loop FEA If you don t enter a label all breakpoints are cleared AlphaBASIC PLUS User s Manual Rev 02 The AlphaBASIC PLUS Debugger Page 22 5 22 5 5Execute AMOS Command Executes an AMOS command For example gt AMOS TIME 11 10 15 AM There are some AMOS commands you should not use such as MONTST DSKANA etc any command which could cause data corruption to your currently open file or inconvenience other users Programs that change the job environment such as LOG should also be avoided Also DO NOT erase the file you are currently editing If you see a Memory allocation failed message it means there wasn t enough memory to execute the AMOS command you may want to increase your memory see Appendix H 22 5 6Find a Specific Label Locates a specified label For example gt SEARCH company EWN DB switches to the program display and positions the cursor on the label company 22 5 7Trap a Verb Defines an AlphaBASIC PLUS verb to be used as a tracepoint Whenever the verb is execu
316. r example if NUM 2 then NUM changes the value of NUM to 2 And if you add a minus sign to a positive number it changes the value to negative An area of memory available to one user A name representing a number or character string that can change during the run of the program A symbol that can represent a range of other characters You might want to think of it as a joker in a deck of cards For example if you wanted to erase three files FILEO1 DAT FILEO2 DAT and FILEO3 DAT you could type all this ERASE FILEO1 DAT ERASE FILEO2 DAT ERASE FILEO3 DAT or you could type ERASE FILEO DAT where the question mark symbol represents all characters or ERASE DAT where represents all combinations of characters in this case all filenames Of course you wouldn t use the second command if you had DAT files you wanted to keep An AlphaBASIC PLUS command that runs an external outside the current AlphaBASIC PLUS program subroutine The subroutines XCALL can call are useful programs many people use and thereby save you the time and trouble of writing such a subroutine yourself AlphaBASIC PLUS User s Manual Rev 02 AlphaBASIC PLUS Document History Revision 00 Printed September 1989 New Document Adapted from the AlphaBASIC User s Manual Revised to include the new features of AIphaBASIC PLUS Revision 01 Printed April 1991 Revised Chapters 2 5 7 8 12 16 and 20 to add new feature
317. rapping routine Use RESUME This is because RESUME clears the area of memory used by the error routine GOTO does not which could cause memory errors 17 5CONTROL C TRAPPING When you press c8 J C during the run of an AlphaBASIC PLUS program the program stops at the next statement What happens next depends on whether an ON CTRLC GOTO is defined or whether error trapping is on or off If no ON CTRLC GOTO is defined and if error trapping is off the program stops and the appropriate message is printed on the terminal If an ON CTLRC GOTO is defined control passes to the routine that handles the Control C If no ON CTRLC GOTO is defined and error trapping is on the error trapping routine is entered with the code in ERR 0 being set to 1 You can then decide what your program is going to do when a Control C is encountered If you simply let the program RESUME you have effectively turned off Control C interrupting which may not be a good idea if your program gets into an endless loop you couldn t stop the run except by re setting your computer Control C trapping lets you prevent users of your program from exiting during a critical time such as during a file update The Control C is detected immediately During an error recovery routine no Control C use is allowed so the program cannot be stopped during this important phase 17 64 SAMPLE ERROR RECOVERY ROUTINE In this sample of an error recovery routine we ll take a ca
318. rgument used by the second format may also take on negative values for a more flexible format When the length is a positive value it represents the number of characters from the beginning position and counting to the right A negative length causes the index to move to the left and returns a substring whose last character is the one marked by the beginning position argument A few examples should show the use of substring modifiers If A ABCDEF then AS 2 4 BCD AS 3 2 DE AS 3 2 CDE AS 3 2 BC AS 3 2 CD AS 4 1 p For example A 3 2 tells AlphaBASIC PLUS to return the substring beginning at character position 3 from the left and ends with character position 2 from the right that is to return all characters between C and E inclusive A 3 2 tells AlphaBASIC PLUS to return the substring beginning with character position 3 from the left and extends 2 character positions toward the left that is return all characters starting with C and work backward two positions to B inclusive Any position values or length values which cause the substring to overflow either end of the main string are truncated at the string end For example AS 3 10 CDEF AS 14 34 ABCDEF The main string to which the substring modifier is applied is actually any expression and does not need to be a defined single string variable For example AlphaBASIC PLUS User s Manual Rev 02 Work
319. ride normal allocation processes if you wish to have the variables allocated in a predetermined manner Also the disk I O system requires variables used be in a specific relationship to each other when used in some of the more sophisticated programs The MAP statement has been included in AlphaBASIC PLUS for the purpose of allocating variables in a specific manner MAP statements are non executable at run time but merely direct the compiler in the definition and allocation of the referenced variables Each MAP statement contains a unique variable name to which the statement applies When the compiler encounters this statement it allocates the next contiguous space in working storage as required and assigns it to that variable All variables not defined in a MAP statement are then automatically assigned storage in sequence for total compatibility with existing standards To eliminate potential allocation problems AlphaBASIC PLUS forces all MAP1 level variables to begin on an even memory address This ensures certain binary and floating point variables begin on word boundaries for assembly language subroutine processing The instruction set performs most efficiently when word data is aligned on word boundaries In interactive mode if an error occurs in the syntax of the statement the variable has already been added to the tree in memory This is the reason MAP statements are not useful in interactive mode except for learning and debugging
320. rmat However while on AMOS systems they are very efficient 6 2 1 2 2IEEE Floating Point Numbers IEEE floating point variables have their format and behavior strictly specified by an international standards body the Institute of Electrical and Electronic Engineers This rigorous specification ensures the transportability of floating point numbers between different hardware platforms and the reproducibility of results of mathematical calculations a notoriously difficult aim to achieve with inherently inexact representations IEEE variables may either be slower or faster in operation on your system than AMOS real numbers If your system has an IEEE math chip incorporated either as a separate chip or built into the CPU IEEE variables may be faster than AMOS real numbers for identical CPU clock speeds If not AMOS real numbers are generally faster but this may vary from system to system AlphaBASIC PLUS User s Manual Rev 02 Variables Page 6 7 6 2 1 3Real Number Characteristics AlphaBASIC PLUS real numbers have the following characteristics AMOS Fpt IEEE Single IEEE Double MAP F 6 F 4 F 8 Significant digits 11 6 15 Largest positive number 1 771038 3 4 10 38 1 8 10 307 approx Minimum positive number 2 9 10 39 1 4 10 45 4 9 10 324 approx 6 2 1 4Real Number Mathematics By definition real numbers are approximations to absolute values Real numbers can hold integers exactly up to a maximum value that depends
321. rogram 9 2 GOSUB occa dR edie drt elt hee ve ee 1 4 9 9 GOTO o netos dada deus s A Edd 1 4 9 12 Graphics conventions 1 6 Hexadecimal values F 1 Higher level languages 1 2 VO POS EDT 11 1 to 11 2 IEEE uS E A ER DAD od 5 4 IE esci duque d ho Ed eR et Ame RR Site ind 9 12 INCLUDE statement 19 2 Increasing execution speed C 2 INDENT 55 2 eke te pos ates Ce ead 22 7 INDEXED mode 0005 15 16 Indexed sequential files 19 1 INDEXED EXCLUSIVE mode 15 16 INDEXED STATS cese eR ty Yas 19 8 IPIE An 5 84s de MEAE ro re MC DS 9 14 15 2 15 10 to 15 11 Input from terminal ss 10 12 INPUT LINE 9 os e Rr 9 17 15 2 15 13 INPUT mode su 5 Deer As 15 16 INPUT RAW ees oi das cue NER 9 18 15 2 15 14 Input Output ier LR RR x 11 2 Input output statements 15 2 INSTR X A B osito 10 6 INT A O E od 10 3 Integer data 2 22 cu Rem AR 14 6 Integer part of a number 10 3 AlphaBASIC PLUS User s Guide Index Page Index 10 Interactive BASIC 1 3 1 5 3 1 Interactive compiler options 3 8 Interactive mode Breakpoints 222i yk Rn EE 4 1 Compiling ad emos d 3 7 to 3 8 Continuing the program 4 2 Deleting lines 3 4 Direct statements 3 3 Editing tes aaa ds TENE 3 4 Exiting sra ae 3
322. rograms In assembly language routines you can test for AlphaBASIC PLUS by examining the value of the longword at AO If it equals 2 AlphaBASIC PLUS is operating You write assembly language subroutines in the same manner you write assembly language programs Use the OBJNAM statement to give it an XBR extension indicating it is a subroutine When an XCALL statement is executed by AlphaBASIC PLUS the named subroutine is located in memory and then executed AlphaBASIC PLUS first saves all registers then sets certain parameters into those registers for use by the external subroutine The addresses of the arguments are calculated and entered into an argument list in memory along with their sizes and type codes The base address of this list is then passed to the user routine in register A3 The arguments may be one of two basic forms eA variable name in which case the argument entry in the list references the selected variable within the user impure area This variable is available to the called subroutine for both inspection and modification eAn expression numeric or string in which case the expression is evaluated and the result is placed on the arithmetic stack This result instead of a single variable is then referenced in the argument list entry It is only available for inspection since the stack is cleared when the subroutine exits AlphaBASIC PLUS User s Manual Rev 02 Page E 2 Appendix E You may not use a non
323. roup of characters following the PROGRAM keyword are evaluated when the program is compiled and therefore must be literal characters or numbers not variables AlphaBASIC PLUS checks each of the fields to determine if the proper range of number or letter is specified There must be a least one space after the PROGRAM keyword If part of your revision specification is incorrect you see an error Here is an example of a full PROGRAM statement PROGRAM Test3 1 0b 103 If your AlphaBASIC PLUS program contains a PROGRAM statement the compiled version of that program the RP file contains the version information you specified The AMOS command DIR displays general information about specified disk files If you use the V option with the DIR command you also see version information for any RP files included in that directory display For example DIR V RP REUN MYPROG RP 2 0B 103 DSK2 50 0 RECEIV RP 15 4 2E 50 INVEN RP 102 7 2 Total of 3 files in 119 blocks If the original program file from which the RP file was generated did not contain a PROGRAM statement DIR displays the version number as 0 0 9 35RANDOMIZE The format is RANDOMIZE AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 25 Resets the random number generator seed to begin a new random number sequence starting with the next RND X function call See Chapter 10 for information on the r
324. routine must either resolve the error or exit the program For example if the program above had merely printed an error message and then RESUMEd back to the line where the error occurred the Divide by zero error still exists AlphaBASIC PLUS again transfers control to the error trapping routine and the program is stuck in an infinite loop Instead the program resolves the error by having the user change the value of the second variable and then resuming program execution AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 18 EXTERNAL ASSEMBLY LANGUAGE SUBROUTINES This chapter discusses Why use external subroutines eAutomatic subroutine loading AlphaBASIC PLUS supports the use of external assembly language subroutine programs that can be called from your AlphaBASIC PLUS programs We discuss the details of writing these subroutines in Appendix E For information about assembly language see your Assembly Language Programmer s Manual and your AMOS Monitor Calls Manual 18 1WHY USE ASSEMBLY LANGUAGE SUBROUTINES There are several good reasons why you might want to use an assembly language program to carry out a function rather than using another AlphaBASIC PLUS program or subroutine Assembly language programs are generally much smaller and faster than equivalent BASIC programs when speed and size are important factors you may want to code parts of your program into assembly language Yet another reason for using assembly language
325. rpreted there is no way to execute a program at any entry point other than its physical beginning You may however pass string literals into a program using the CMDLIN function see Chapter 10 or other data by using the AlphaBASIC PLUS assembly language subroutine COMMON to store data in a common memory area COMMON lets you store information either in system memory where programs run by all users on the system can access the information or in your memory partition where only programs run by you can access the information For details on using COMMON see your AlphaBASIC XCALL Subroutine User s Manual In addition to sharing information you can use the common area to pass parameters to the chained program For example the current program can pass a parameter to the new program which it uses in an ON GOTO or SWITCH statement to begin execution at some point in the new program based on the value passed in the parameter Another way to make sure chained programs can share information is the use of disk files The current AlphaBASIC PLUS program can open a data file write the variables it wants to share into it and then close it When the new file is chained in it can open the file and read the necessary information Note that you may not CHAIN out of a user defined function or a subprogram You must return back to the main program first 16 1 2Chaining to System Functions It is sometimes desirable to transfer execution to a system fu
326. rrors see Chapter 17 If you specify WAIT FILE AMOS doesn t report an error if the program tries to access a locked file but instead puts the job using the program to sleep until the file is available 15 7FILE LOCKING FOR RANDOM FILES With Random files you have a choice of how you want to OPEN the files If you OPEN a file using RANDOM mode the monitor OPENS the file for your exclusive use If you specify RANDOM FORCED mode the file is OPENed for shared use The RANDOM FORCED mode is useful because it allows many users to access the same file at the same time without any updating problems When a file is OPENed for shared access AMOS makes certain any records you are working with are locked before they are changed AMOS recognizes if you are trying to WRITE to an unlocked record and halts your program displaying a Record not locked error message unless you handle the error with an error trapping routine The WAIT FILE option applies to Random files also Random files opened in RANDOM FORCED and INDEXED modes have another option called WAIT RECORD which works just like WAIT FILE except it applies to records inside the file 15 8FILE LOCKING FOR ISAM PLUS FILES You can also use ISAM Indexed files in the same manner If you specify INDEXED when you OPEN the file AlphaBASIC PLUS OPENS it for shared use Or you can specify INDEXED EXCLUSIVE when you OPEN the file which opens the file for your exclusive use See Chap
327. ry key is ABCD from the file opened on channel 3 and stores it in varlist If no record in the file has the key ABCD the GET operation returns the record with the next highest key The status variable specified in the OPEN is set to ISAM NF if no key is found greater than or equal ISAM EQ if a key ABCD is found and ISAM GT if key ABCE or greater is found 19 3 3GET NEXT GET NEXT LOCKED and GET NEXT READ ONLY GET NEXT performs sequential access It reads the next record in key order into the record buffer GET NEXTLOCKED locks the record for update and has the same syntax as GETNEXT GET NEXT READ ONLY gets the record for a read only operation and the format is also the same as GET NEXT The key number used is the last GET or FIND operation The format is GET NEXT f ile channel WAIT RECORD varlist GETNEXT GET PREV and their LOCKED and READ ONLY variants return these status values in the status variable ISAM NF 3 Key not found ISAM NA 2 Record not available locked ISAM EQ 0 Key found If the key is found the relative record number variable is updated 19 3 4GET PREV GET PREV LOCKED and GET PREV READ ONLY GET PREV performs reverse sequential access GET PREV LOCKED locks the record for update and has the same syntax as GET PREV GET PREV READ ONLY gets the record for a read only operation and the format is also the same as GET PREV It reads the pre
328. s Base Income and Tax Rate Each of the parameters are unformatted variables having two lower level MAP variables each The calling program might call TaxAda in the following manner map 1 CLIENT BASE INCOME AlphaBASIC PLUS User s Manual Rev 02 Page 16 8 Chapter Sixteen map 2 CL DEDUCTIONS f 6 map 2 CL DEPRECIATION f 6 map 1 CURRENT TAX RATE map 2 TR BASE PERCENTAGE f 6 map 2 TR CL 13 DEDUCTION f 6 CL DEDUCTIONS 1 CL DEPRECIATION 0 25 TR BASE PERCENTAGE 27 8 TR CL 13 DEDUCTION 0 25 SUBCALL TAXADD CLIENT BASE INCOME CURRENT TAX RATE The PARAMETER statements MUST appear immediately after the SUBPROGRAM name except for blank and comment lines You may also use INCLUDE to include the parameter list or part of it AlphaBASIC PLUS allows you to add a P e g INCLUDE PARAM BPI P to the INCLUDE statement so a MAP1 statement in the included file is interpreted as a PARAMETER statement allowing you to include the same file in a main program and a subprogram Each PARAMETER statement defines a formal parameter and defines the types and names of the formal parameters When you SUBCALL a subprogram you specify the name of the subprogram and a list of varia
329. s You may use line numbers only for certain lines in a compiled program if you like just because you use line numbers does not mean all the lines have to have numbers If you have a line number on the line at which an error occurs AlphaBASIC PLUS is able to tell you where that error occurred by displaying that line number Without line numbers it can only report an error occurred but not where You may want to use line numbers in special places when debugging the program to help locate errors A disadvantage of line numbers is they occupy space in memory making your program slightly larger and slower AlphaBASIC PLUS User s Manual Rev 02 Page 2 2 Chapter Two 2 2LABELS AlphaBASIC PLUS allows the use of labels to identify locations in a program The exact rules for label names are described in Chapter 6 Briefly a label must be the first thing on a line apart from an optional line number it must start with a letter contain only alphanumeric chararacters apostrophes and underscores and be terminated by a colon For example ERROR MESSAGE Addition_Routine START It is important to remember you may not place a space between the label and its colon doing so causes AlphaBASIC PLUS to think you have entered a multi statement line rather than a label A label may be followed by a program statement on the same line or it may be the only item on the line The use of labels is similar to the use of line nu
330. s and clarify text Added Chapter 23 to document the new Debugger Revision 02 Printed September 1996 New compiler and runtime switches added PRAGMA rewrote memory handling data types and subprogram sections removed old Chapter 9 added appendices and J added RNDN function added string work area discussion Other editing changes throughout Revision 03 Printed May 1997 Added notes to PX and R switches in Chapter 5 changed ODTIM description in Chapter 10 Chapter 11 updated VER Chapter 19 changed DELETE RECORD In Appendix J added rules about option use and description of option number 1 Revision 04 Printed November 1997 Small changes to ODTIM in Chapter 10 and DATE in Chapter 11 AlphaBASIC PLUS User s Manual Rev 04 AlphaBASIC PLUS User s Guide Index e do dd al ahd E 2 2 12 5 D C OE da dE oe 12 3 15 2 A a o ed Lo t e 12 6 SEESESE Ta ade ando E 4 SOQTARGQ eset A A Ta O A L aa E 3 Oh he E NA 2 3 5 2 2 2 a nd tds aa brat s efus Ah d 12 7 O vorrei pros i age toe eens 8 1 9 22 12 7 A 12 7 PEO irrita 12 5 BP extension esee 3 5 5 3 BP xxm ea a Ba a 1 5 BPR ds das os ls edi 18 1 BPR TE vu a a a went H 2 DAT as ts 15 3 EI extensi N rn as ems 5 3 dI PEOR TEM 1 5 SPG extension llle 16 6 ABR Aye etx dde st race owe 1 5 A MERCEDE RENE 2 2 3 3 SNAM am LM Ee O Di AL DAS i 8 1 9 22 Qc Ra Ma ee M Rc Ml m HI
331. s case sensitive eMust be less than 500 characters long The case sensitivity rule and the rule concerning the apostrophe and underscore mean that AlphaBASIC PLUS treats the following names as referring to different items REC SIZE Rec Siz Rec Size rec siz rec_siz rec size 6 1 1 1Variable Names In addition variable names must follow these additional rules eA variable name cannot start with the characters FN or FN if the F COMPLP option is used otherwise it is interpreted as a user defined function eThe entire variable name cannot be in the list of reserved words in Appendix B This check is done without regard to case eOptionally the last character of the variable name can be either a or a to designate the variable s data type The following variable names are legal CUSTOMERNUMBER CUSTOMER NUMBER CUSTOMER_NUMBER CUSNO CUST1 NO CUST2 NO 3 CUS_NO CUSNO CUSNOS CUST NAMES The following variable names are illegal 1ST NAME Does not start with an alphabetic character _NAME Does not start with an alphabetic character FIRST NAME Space terminates a name FNAME Legal only if the F COMPLP switch is used OUTPUT Is a reserved word Output Is a reserved word check is case insensitive AlphaBASIC PLUS User s Manual Rev 02 Variables Page 6 3 6 1 1 2Label Names Labels follow these rules in addition
332. s is the default condition unless changed by a DIVIDE BY 0 command see above 9 27NOECHO Turns off the keyboard echo The format is NOECHO When the keyboard echo is off no characters are displayed on the terminal as they are entered from the keyboard This is useful for entering passwords or other data you want only the user to see Use the ECHO statement to turn the echo on again Don t turn the ECHO off if you are going to use the AMOS statement to execute AMOS commands because you could hang your job NOECHO is not allowed as a direct statement in interactive mode 9 280N CTRLC GOTO AND RESUME Transfers control if a C is used during the program execution The format is ON CTRLC GOTO line number or label You can change the line number label by specifying a new one by using the statement more than once in a program or turn the GOTO off by specifying 0 as the line number While you use ON CTRLC GOTO Control C is shut off until the RESUME statement is used see the next section for more on RESUME This statement is used in error recovery for more information see Chapter 17 AlphaBASIC PLUS User s Manual Rev 02 Page 9 20 Chapter Nine 9 290N ERROR GOTO AND RESUME Turns error trapping ON and OFF The formats are ON ERROR GOTO 500 ON ERROR GOTO traproutine ON ERROR GOTO In the first two cases if an error occurs the program goes to the specified area In the third case the program ends and th
333. s of operator precedence explained below to determine which part of the expression is done first AlphaBASIC PLUS recognizes the following mathematical operators addition or unary plus equal subtraction or unary minus lt less than multiplication gt greater than division lt gt unequal A raise to power gt lt unequal t raise to power unequal string literal lt less than or equal NOT logical NOT lt less than or equal AND logical AND gt greater than or equal OR logical OR gt greater than or equal DIV integer division MOD integer remainder FMOD floating point remainder EQV logical equivalence USING expression formatting XOR logical XOR MIN minimum value MAX maximum value The difference between division and DIV integer division and between FMOD and MOD are described in the section on Rules for Calculations AlphaBASIC PLUS cannot divide a number by zero If a division by zero occurs an error will occur AlphaBASIC PLUS s handling of such a case can be controlled by the DIVIDE BY ZERO statement described in Chapter 9 AlphaBASIC PLUS automatically evaluates expressions for you For example consider the statement PRINT 32 100 2 MAX 25 30 54 First AlphaBASIC PLUS computes the multiplication operation determining 32 100 equals 3200 Then it computes the division operations determining 3200 2 equals 1600 and 30 54 equals 5556 Next it adds 25 and 5556 to get 25 5556 Fin
334. s own set of parameters on the Arithmetic Stack If there is insufficient room on the Arithmetic Stack RUNP throws a trappable runtime error 33 Stack overflow You can prevent this situation from reoccuring by increasing the STACK setting in the BPR file RUNP can use the free area at the top of the memory partition reserved by the MINF setting in the BPR file for eExecuting the built in AMOS function el oading any XCALL subroutines not already loaded into system or user memory el oading any device drivers that AMOS requires this is more properly thought of as a function of AMOS rather than a function of RUNP You can increase the size of this reserved area by increasing the MINF setting in the BPR file AlphaBASIC PLUS User s Manual Rev 02 Page H 6 Appendix H H 2 5Calculating Runtime Requirements It is hard to predict the minimum requirements for a program Execution order can affect the results It is rare to set DELTA to anything but the 300 byte default Decreasing this value is very risky and increasing it is only indicated in very rare situations where RUNP suddenly had to do a large number of nested calls internally without having to do a memory allocation in the Heap Symptoms of stack heap collision problems would be obtaining erratic results after executing a particularly complex single AlphaBASIC PLUS statement at a deeply nested level when you can guarantee that an XCALL has not run wild The MINF requireme
335. s s 1 4 Conditional statement 9 12 Constants oer iaasa se ree ek eens 6 10 7 4 9 3 Alternative radix o ooo 6 11 Character 42925 ees ao eod et ees 6 10 Defining uoce CRI e ba RR 9 3 Floating point v 24 220 4084 centage ges 6 12 ENING 2s cos staged ee Wali arsihan Pe aie ee Sug 6 12 CONT cts ros 4 2 Continuation lines 2 3 5 2 Continuing an interrupted program 4 2 CONTO Ge is corem eS aid wai READY 4 3 4 5 5 11 AlphaBASIC PLUS User s Manual Rev 02 Page Index 3 AlphaBASIC PLUS User s Guide Index Control G trap idee RR aad aed 9 19 17 4 Control characters ER A Ue ng e 1 7 Control variables o 9 7 Controlling compile 5 5 Converting arguments to binary E 3 Converting numbers to string 10 10 Converting to integer 10 3 Converting to lower case 10 7 Converting to uppercase 10 10 Copying a string ear 10 6 COS X oos n a a PEN Ed 10 4 CREATE RECORD east ds 19 6 Creating a program with AlphaXED 5 1 Creating a record ooo oooooo 19 6 Creating an ISAM PLUS file 19 8 Creating interactive programs 3 4 DAEAULE be coros hehe SERE ALPES RS 9 3 BATA Lune densus a 9 3 9 25 Data Base Mangagement 21 1 Dates audacia anh nor o e d 19 2 Data formats cea Lee EE edes 1 4 Array structures o o o o o
336. se where the user of your program is asked to input two numbers The program then divides the first number by the second number But what if the user enters a zero as the second number Normally BASIC halts the run at that point and prints a Divide by zero error message You can use the DIVIDE BY ZERO statement to turn off the error but then the user gets an answer of zero if they enter a zero as the second number By using an ON ERROR GOTO statement and an error recovery routine the program can handle the error itself AlphaBASIC PLUS User s Manual Rev 02 Error Trapping Page 17 5 ON ERROR GOTO DIVIDE BY ZERO INPUT Enter two numbers A B PRINT A divided by B equals A B END DIVIDE BY ZERO If error is not divide by zero exit the program 1 D ERR 0 10 THEN amp PRINT System Error Detected Exiting END PRINT Division by zero does not work INPUT Please r nter the second number B RESUME Go back to the line where th problem occurred Two sample runs of the program look like this Enter two numbers 2 3 RETUR A divided by B equals 666667 Enter two numbers 25 0 RETURN A divided by B equals Division by zero does not work Please re enter the second number 5 EIR A divided by B equals 5 Note a successful error trapping
337. separator between the hour and the minute values 27 Affects hours output if 12 hour clock suppress any leading zero If 24 hour clock ignored Seconds Options 10 Omit seconds otherwise include seconds preceded by the time separator Punctuation Options 13 Force a colon as the time separator otherwise use the character defined as the time separator in the job s language definition file 17 Do not output separator between the minute and the second AlphaBASIC PLUS User s Manual Rev 04 Page 10 16 Chapter Ten To determine the flag value follow these steps 1Decide which options you want from the tables above and note the number of each option 2For each number in step 1 total the corresponding value in the table below 3 The grand total value is flag value Option Flag Values 0 1 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256 9 512 10 1024 11 2048 12 4096 13 8192 14 16384 15 16 17 18 19 20 21 22 23 24 25 26 27 28 32768 65536 131072 262144 524288 1048576 2097152 4194304 8388608 16777216 33554432 67108864 134217728 268435456 If date is zero any value given for time is ignored and the current time and date are used If date is not zero and time is zero the time is returned as midnight date is interpreted in separated format and time is interpreted in internal format These are the default formats for the DATE and TIME functions see Chapter 11 For convenience a fl
338. sferred by the system I O is the one whose record number corresponds to the record number variable The format of the READ statement is READ file channel variable s AlphaBASIC PLUS User s Manual Rev 02 Page 15 20 Chapter Fifteen For example if your OPEN statement is OPEN 1 STOCK DAT RANDOM rec size rec number and your READ statement is READ 1 PART NUMBER PART NUMBER is filled with the data in whichever record number is currently defined in the variable rec number from the file STOCK DAT The variable in the READ statement may be any format but should match the designated record format The data is read into the variable s as unformatted bytes without regard to variable type Of course if it is transferred into the wrong type of variable you get unexpected results and or errors when you use that variable The data is transferred into the variable s until they are completely filled If you transfer less no error occurs If the record is longer than the variable specified all excess data in the record is not transferred If you try to transfer more data than is in the logical record size you get an error message The most efficient use of random files comes when the variable or variables used are mapped by a MAP statement to the exact picture of the record format in use See Chapter 14 for information on MAP statements 15 9 14READL READL is a form of the READ statement that ca
339. ssage number This can be a literal or an expression For example AlphaBASIC PLUS User s Manual Rev 03 Page 10 12 Chapter Ten READY PRINT ERRMSG 10 Divide by zero or not recommended IF ERRMSG ERR 0 lt gt Divide by zero THEN EXIT Do not rely on the exact text of the error message lt could change from version to version 10 4 5ERR X Returns a status code referring to program status during error trapping For a complete list of these codes and examples of using ERR X see Chapter 17 If X is 0 ERR returns the code of the error detected if X is 1 ERR returns the number of the last program line encountered before the error occurred If X is 2 ERR returns the file number of the last file accessed If X is 3 ERR returns the error status code from the JOBERR field of the Job Control Block this can be used after an AMOS statement to see how the command executed See Appendix G for a list of AMOS error codes 10 4 6FILEBLOCK X Returns the absolute address of the Data set Drive Block DDB corresponding to the OPENed channel specified by X For example FILEBLOCK 1 returns the DDB of the file opened on file channel 1 This is useful to pass a DDB address to an XCALL assembly language subroutine You get an error message if the file is not open or is open on channel 0 10 4 7GETKEY X Reads a character from the terminal The format is GETKEY X translation table filenam
340. statements may be continued on the next line by using the ampersand amp symbol as the last character on the line A comment may come after the ampersand but it must begin with not REM since it is not part of the code For example IF STOCK NUMBER gt 599 THEN amp Compare stock 4 GOTO OVER STOCKED Notice the example above though appearing on two lines in your source file is actually treated as one statement by AlphaBASIC PLUS Therefore do not separate a line AlphaBASIC PLUS User s Manual Rev 02 Page 2 4 Chapter Two being continued from the line before by a label or line number For example this code causes an error IF STOCK NUMBER gt 599 THEN END LOOP GOTO OVER STOCKED You may also use the ampersand symbol after a colon Since any statement line may be indented as you please when your program is a disk file use of continuation lines and indentation plus eliminating line numbers as discussed in the next section allows you to give your source program a more structured look than allowed by more conventional BASICs Here s an example of a structured code format TIME OF DAY TIME 3600 IF TIME OF DAY gt 12 AND TIME OF DAY lt 13 THEN PRINT It s Lunch Time ELSE PRINT The day s journey is half over amp but you still have work to do ENDIF
341. string variable and so reads the symbol as a string concatenation operator In the third line BASIC knows a numeric result is expected because NUMERIC is a numeric variable and so reads the symbol as an addition operator VALUE1 123 VALUE2S 456 STRINGS VALUE1S VALUE2 1 3 NUMERIC VALUE1S VALUE2S 1 3 PRINT NUMERIC NUMERIC STRINGS STRINGS The program above prints NUMERIC 579 STRINGS 123 You may apply substring modifiers to subscripted variables or expressions containing subscripted variables Be careful not to confuse substring modifiers with subscripted variables For example AlphaBASIC PLUS User s Manual Rev 02 Page 8 4 Chapter Eight E AS 2 3 designates a location in array A AS 2 3 designates a substring of string A AS 1 5 2 3 designates a substring in location A 1 5 These are valid uses of the substring modifiers Q AS 1 9 2 5 QS AS 1 B 3 5 3 Substring modifiers return a string value These may be used as part of string expressions For example Q AS BS 2 5 AS 2 2 C 5 3 You may apply substring modifiers to the left side of an assignment in order to alter a substring within a string variable Only that portion of the string defined by the substring modifier is changed The other characters in the string are not altered For example
342. subroutine version The subroutine specified in the XCALL statement is not in the correct format for the processor you are running on You may have to rewrite or re assemble the subroutine Invalid syntax code Check the format for the statement you used and try again Invalid token Contact Alpha Microsystems and report the problem and how it happened 210 to unopened file channel The program tried to write to or from an unOPENed file Check your code and make sure the file is OPEN before you try to use it and check the file s channel number AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 13 ISAM KEY expected Adjust your code so the expected condition is fulfilled Keyword used as variable Change the keyword to a variable name Label is out of scope You tried to transfer to a label within a function or loop from outside Revise the instruction Label or line number out of scope You tried to transfer to a label within a function or loop from outside Revise the instruction Label undefined You referred to a label that doesn t exist in your program Check your syntax or define the label Line number is out of scope Use a smaller line number Line number must be 1 to 65535 Change the line number Line number not found The specified line was not found for a DELETE LIST etc operation Line number undefined You referred to a line that doesn t exist in your program Check your syntax or creat
343. system The stack is built at the top of the memory module allocated for use by RUNP in the user partition and grows downward as items are added to it When the external subroutine is called A5 points to the current stack base Since the arithmetic stack may contain valid data the external subroutine must not use the word indexed by A5 or any words above it E 2ARGUMENT LIST FORMAT The list of arguments specified in the XCALL statement may range from no arguments at all to a number limited only by the space on the command line To pass these arguments to the external subroutine an argument list is built in memory which describes each variable named in the list and tells where it can be located in the user impure area The variables themselves are not actually passed to the subroutine but rather their absolute locations in memory are In this way the subroutine may inspect them and modify them directly in their respective locations This does not apply to expressions which are built on the stack as described previously AlphaBASIC PLUS User s Manual Rev 02 Writing Assembly Language Subroutines Page E 3 A3 points to the first word of the argument list which is a binary count of how many arguments were contained in the XCALL statement Following this count word comes one 5 word descriptor block for each argument specified If there are no arguments in the XCALL statement the argument list consists only of the single count word containi
344. t This means the value of 50 12 is multiplied by the scaling factor of 2 digits 100 and stored as the floating point value of 5012 Since this value is an integer it has absolute accuracy Just before printing AlphaBASIC PLUS divides this number by the scaling factor to reduce it to its intended value of 50 12 Other conversions have been included into the system to handle the subtle effects of storing scaled numbers For example when converting scaled numbers to integer or floating point format AlphaBASIC PLUS must unscale the number first before converting it When AlphaBASIC PLUS multiplies two scaled numbers together the result is a number which must be unscaled once while division of two scaled numbers creates exactly the opposite problem Dealing with scaled numbers for exponential logarithmic and trigonometric functions creates even more exotic problems but AlphaBASIC PLUS handles them all for you AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 14 MAPPING VARIABLES This chapter discusses the following subjects What variable mapping is eThe format of MAP statements eHow to use MAP statements eHow memory is allocated by MAP statements el ocating variables during debugging 14 1WHAT IS VARIABLE MAPPING Mapping variables is a method of grouping variables together The ability to group variables together is useful when those variables contain related information Variable mapping is a powerful tool similar to COBOL data
345. t External Program cosida eee 22 9 22 5 28 Break at Subprogram 2 2 2 0 eee 22 9 22 6 DEBUGGING A SUBPROGRAM 00 0 cee eee eee 22 10 PART FIVE APPENDICES APPENDIX A MESSAGES APPENDIX B RESERVED WORDS APPENDIX C PROGRAMMING HINTS C 1 MANAGING MEMORY eire Seit oie Oat ae ee RR Pede C 1 C 2 INCREASING EXECUTION SPEED 0000 0a eee C 2 C 3 MAKING YOUR SOURCE PROGRAMS EASIER TO READ C 2 APPENDIX D SCREEN HANDLING CODES AlphaBASIC PLUS User s Manual Rev 04 Page x Table of Contents APPENDIX E WRITING ASSEMBLY LANGUAGE SUBROUTINES E 1 REGISTER PARAMETERS vario a E 2 E 2 ARGUMENT LIST FORMAT x g ncsec sated ie E 2 E 3 CONVERTING ARGUMENTS TO BINARY FORMAT E 3 EA FREE MEMORY USAGE so uct et a E LR EA E 4 ES LOCATING OPEN FILES ceire tta hice IRR od RS E 4 E6 PROGRAM HEADERS Ai cse edere oco AS E 4 APPENDIX F CHARACTER SETS APPENDIX G ERR 3 ERROR CODES APPENDIX H MEMORY H 1 MEMORY REQUIREMENTS 2tac reese van a ar a H 1 H 2 MEMORY MANAGEMENT 200 0 eee eee eee H 2 H24 Me BRA 6 oe reete Sir ea ree xev H 2 H 2 2 BPR File Settings iss cos Con Ee M ende RE Ee des H 2 H 2 3 RUNP Memory Partition Layout lle H 3 H 2 4 RUNP S Use of the Stacks Heap and Free Area H 4 H 2 5 Calculating Runtime Requirements 05 H 6 H 2 6 COMPLP and RUNP C Settings o ooo ooooooo H 6 APPENDIX I THE STRING WORK AREA APP
346. t is STRSIZ value The default string size is 10 characters The statement STRSIZ 25 for example causes all newly allocated strings which follow to have a maximum size of 25 characters instead of 10 This includes the allocation of string arrays The size value is evaluated at compilation time and so must be a single positive integer The maximum size you can allocate depends on the amount of memory on your system and on how many variables you use but cannot be greater than 65 535 bytes 9 48SWITCH CASE Selects sections of code based on a comparison of cases The format is SWITCH expression CASE constant statement s CASE constant statements s DEFAULT statement s ENDSWITCH AlphaBASIC PLUS User s Manual Rev 02 Page 9 30 Chapter Nine The constants in each CASE statement must be the same type as the expression in the SWITCH statement and cannot be variables The constant in each CASE statement is compared to the expression in the SWITCH statement If they are equal the statements following the CASE statement are executed Unless an explicit GOTO or EXIT statement is used control passes to the next CASE whether that CASE matched or not Once one match is found the remaining statements in the SWITCH CASE block are executed Therefore if you do not want subsequent CASEs to be executed you must explicitly use a GOTO EXIT or RESUME if the SWITCH is inside an error tr
347. t is best to use random files when your program uses grouped mapped variables Let us take a look at an example defining a logical record Our program probably uses a file containing a large number of logical records in this format each record containing information about a single check In effect MAP statements give us a way to form a template in memory into which you can read information from the random file and transfer information from the program to the file This allows you to quickly and efficiently read in an entire group of information whose elements may be of different types and sizes and to access information in that group simply For example MAP1 CHECK INFO MAP2 CHECK NUMBER F 6 MAP2 DATE S 6 MAP2 AMOUNT F 6 MAP2 TAX DEDUCTIBLE B MAP2 PAYEE S 20 MAP2 CATEGORY S 20 MAP2 BANK ACCOUNTS MAP3 SAVINGS S 20 MAP3 TERM S 20 MAP3 CHECKING S 20 Define a file containing an account balance MAP2 ACCOUNT BALANCE S 22 DSK1 BALANC DAT 200 1 Once these MAP statements have been executed we can access the group of variables as a whole by specifying CHECK INFO or we can access specific sub fields in the record for example BANK ACCOUNTS or CHECKING For example once the program has filled the variables with the specific data for a record we can write it to the file by saying WRITE 1 CHECK INFO
348. t run time for input and output conversions Negative scaling moves the 11 digit window to the left A negative scaling factor takes care of those cases where your numbers are too LARGE rather than too small A few words of caution are in order here Once AlphaBASIC PLUS detects the SCALE statement during compilation AlphaBASIC PLUS scales all subsequent constant values by the scaling factor so they are stored properly If you execute a computation between numbers with different scale factors you get incorrect results For this reason it is a good idea to use the SCALE statement at the beginning of your program before any variables are defined In addition a run time command is generated in the executable program which causes the actual scaling to be performed on INPUT and PRINT values when the program is running very strange results may come out unless you are completely familiar with the m If two or more different SCALE statements are executed in the same program some compile time and run time conversion processes Let s add a SCALE argument to our previous program SCALE 2 SIGNIFICANCE 11 PRINT 26 4 INT 26 4 now it gives us the proper answer 4 If you are using a positive scaling factor to adjust real numbers note SCALE does nothing to prevent inaccuracies if the scale factor is not large enough to cause AlphaBASIC PLUS to handle your data as integers AlphaBASIC PLUS User s Manual Rev 02
349. tart of a subprogram is defined by a SUBPROGRAM statement and the end marked by a SUBEND statement A calling program uses the SUBCALL statement to execute a subprogram lt is the appearance of the SUBPROGRAM statement that makes the compiler produce a subprogram file with a SPG extension lt is not a good idea to give a subprogram the same name as the main program file even though they have different extensions because COMPLP creates an RP file and then renames it to SPG when it finishes if the file is a subprogram This would erase your main program RP file and could cause confusion AlphaBASIC PLUS User s Manual Rev 02 Page 16 6 Chapter Sixteen When a progam SUBCALLs a subprogram the SUBCALL specifies which subprogram to execute as well as the parameters being passed The runtime system will search for the subprogram using the following scheme 1Looking within the same RP file for a subprogram with the same name 2Looking in user memory for a SPG file with the same file name 3Looking in system memory for a SPG file with the same file name 4Looking on disk for a SPG file with the same name The search path for disk searching is aYour log in device drive and PPN dev f p pn b Your library account that is your log in device drive project number and programmer number set to zero dev p 0 c The AlphaBASIC PLUS library account DSKO0 7 35 The ability to generate an external subprogram allows that subpro
350. tected Device does not exist Disk not mounted Redimensioned array Invalid filename Invalid syntax code Invalid subroutine version Record in use File cannot be DELETEd Record not locked LOKSER queue is full Illegal ISAM sequence File not open Remote not responding Illegal key String overflow File is open exclusively Reserved for expansion Too many files open Illegal record size Too many parameters to function Illegal channel number Significance out of range Cannot pass single value to subprogram array Bad symbolic key not mapped in ISAM code 7 Used to resume execution of the program after the error recovery procedure has been performed It also turns Control C detection back on a Control C interrupt is not allowed while AlphaBASIC PLUS processes the error trapping routine It takes on two forms similar to the forms of the ON ERROR GOTO statement The first form specifies a line number or label in the program where the execution is to be resumed RESUME 410 RESUME TRY AGAIN The second form specifies a line number of zero or no line number at all and causes the execution to be resumed at the statement which caused the error to occur AlphaBASIC PLUS User s Manual Rev 02 Page 17 4 Chapter Seventeen RESUME 0 RESUME Both forms cause the error condition to be cleared and turns on error trapping again You should never use the GOTO statement to exit from an error t
351. ted the debugging stops at that point For example gt TRAP if RETA You may TRAP up to 16 verbs at atime If you don t enter a verb it lists all TRAPs currently set IF LOOP and DO loop statements are compiled into assembly code which causes some loops to look the same to TRAP If you TRAP an IF statement execution stops at DO WHILE DO UNTIL LOOP WHILE and LOOP UNTIL Trapping on DO also traps DO WHILE and DO UNTIL Trapping LOOP also traps LOOP WHILE and LOOP UNTIL 22 5 8Turn Off TRAP UNTRAP turns off the TRAP on the specified verb or turns off all TRAPs if no verb is entered For example gt UNTRAP iff RETURN AlphaBASIC PLUS User s Manual Rev 02 Page 22 6 Chapter Twenty Two 22 5 9Send Program Display to Another Terminal The ATTACH command re directs the input output display of the program to a specified terminal if you leave off the name your own terminal is used This is useful so your program s screen displays don t mix with the debugger s output For example gt ATTACH terml ATTACH is not operative when you are using the AMOS command 22 5 10Display File Channel Information The CHANNEL command displays information about a specified file channel number For example gt CHANNEL 2 Channel number 2 DDB display Filespec INVENTORY DAT D ERR O 22 5 11Print Error Value ERR prints the value the ERR function would return For example gt ERR 2 RETURN ERR 2 12 22
352. ter 19 for information on ISAM files AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 9 15 9FILE STATEMENTS E AlphaBASIC PLUS automatically closes all open files when the program exits or when a CHAIN statement is executed if the files have not already been explicitly closed by use of a CLOSE statement If your program should be terminated abnormally for example by a system crash or power failure and a file was not closed with a CLOSE statement AlphaBASIC PLUS may not have updated the last record However the file is unlocked if it was locked All file statements are valid as direct statements in Interactive Mode but AlphaBASIC PLUS closes any open files before it executes a RUNP command This prevents statements in an executing program from reading or writing to files which were opened by a direct statement Each open file requires about 600 bytes of free memory for buffers and control blocks The following sections in this chapter show you the general format of each of the file statements and give detailed examples of their uses 15 9 1ALLOCATE The ALLOCATE statement marks an area of the disk which you may then open for random processing This area may contain old data you may want to write blank data to the area before using it An attempt to allocate a file which already exists results in an error message A random file need only be allocated once and may then be opened for random read
353. ternal device A whole number That is a number with no decimal part For example 3 Mode of AlphaBASIC PLUS operating in which the computer and the person writing or running a program interact The computer responds directly to every input by the operator Indexed Sequential Access Method A name marking a place in a program so other lines in the program can transfer control to the spot For example if you had a subroutine that adds three numbers you might label it ADD THREE NUMS The label may not contain spaces and must have a colon after it though you do not use the colon when referring to the label In AlphaBASIC PLUS a group of subroutines programs in a special account These subroutines programs can be called by or incorporated in your AlphaBASIC PLUS programs The process of displaying the contents of an AlphaBASIC PLUS program so you can see the lines of code making up the program An actual value rather than a variable For example in AS This is a literal string the quoted material to the right of the equal sign is a literal string whereas A is a string variable AlphaBASIC PLUS User s Manual Rev 02 Page 6 LOCAL VARIABLE LOGICAL OPERATORS LOOP MAPPED VARIABLE MOUNT NULL VALUE OUTPUT Glossary A variable whose value can be accessed only from a limited part of a program In AlphaBASIC PLUS this occurs within function definitions and inside subprograms In functi
354. tes that must exist between the top of the heap and the bottom of the stack at all times If the gap is any smaller RUNP will abort with a non trappable runtime error STACK HEAP COLLISION FATAL MAXS The maximum size of the stack heap area that RUNP allocates AlphaBASIC PLUS User s Manual Rev 02 Memory Page H 3 MINF The minimum size of the user memory partition not used by RUNP This area is left untouched by RUNP The free area can be allocated by GETMEM and GETIMP calls If MINF bytes cannot be left free then RUNP aborts with the error 2STACK HEAP NO MEM MINS The minimum size of the stack heap area that RUNP allocates If RUNP cannot allocate this amount RUNP aborts with the error 2STACK HEAP NO MEM STACK The size of the AlphaBASIC PLUS Arithmetic Stack This is the stack pointed at by Register A5 when an XCALL executes The value item is a decimal number representing the number of bytes for the appropriate setting You can add a K suffix to indicate kilobytes or M to indicate Megabytes H 2 3RUNP Memory Partition Layout As RUNP LIT is a program written in C the memory architecture of the runtime environment is heavily influenced by that required to execute any C program There are three crucial memory areas eThe DSECT area This area is RUNP s impure area for some of its internal variables The size of this area is decided by the programmer who wrote RUNP and cannot be altered The DSECT area is allocated
355. the File Locking queue to hold it You may want to either delete some of the records files in the File Locking queue or increase the size of the queue See your File Locking System User s Manual File not found Check your specification and your directory Make sure the account is correct AlphaBASIC PLUS User s Manual Rev 02 Page A 8 Appendix A File not open Your program attempted to access an unOPENed file Have your program open the file before access is attempted File specification error The file specification you gave in a file operation OPEN LOOKUP etc is in error All file specifications must conform to the system standard devn filename extension p pn File type mismatch Your program tried to perform a sequential operation on a random file or vice versa Make sure you are using the correct files and using the correct file statements First logical unit not mounted The first logical unit on the drive your program was trying to access was not mounted Mount the unit and try your program again Function definitions cannot be nested Move the inner function definition out of the outer one Function undefined You referred to a function that doesn t exist Check your spelling or define the function 2GOTO expected Adjust your code so the expected condition is fulfilled 2GOTO or GOSUB expected Adjust your code so the expected condition is fulfilled lllegal channel number Channel numbers must be i
356. the file USING SEQUENTIAL FILES FOR INPUT 1Use a file for input only if it already exists and contains data You may wish to use a LOOKUP statement to make sure the file exists before trying to open it 2Use the OPEN statement to open the file for INPUT The file is open for shared use other programs can access it while you use it 3Use INPUT LINE INPUT or INPUT RAW statements to read data from the file specifying the file channel number associated with the file by the OPEN statement 4Check the EOF function after each input to make sure you haven t read beyond the end of the file 5 When finished use the CLOSE statement to close the file 15 5RANDOM FILES Random access or direct access files are more complex than sequential files but offer a more flexible method for storing and retrieving data in different formats Random files are written in unformatted or packed data mode Random file disk blocks are contiguously allocated on the disk The major advantages of random files over sequential files are the speed and flexibility with which you may access data in a random file You may only open a sequential file for input OR output but you may open a random file for input and output simultaneously Accessing data in a sequential file requires your program to step through the file record by record In the case of a random file however you may access any record without referring to any other record in that file In additio
357. the size by MAPing the required array variable see Chapter 14 or by using a DIM dimension statement For example to set the array NUMBER to hold 20 values MAP1 NUMBER 20 F 6 or DIM NUMBER 20 One of these statements must precede the use of the array variable in the program You can set each array variable to whatever size you need It is a good idea to set up the array without much overhead Dimensioning an array for more subscripts than you need can use up valuable memory space Once an array has been dimensioned by a MAP or a DIM statement it may not be redimensioned in the same program ol You may not use DIM statements within user defined functions ul You can also make multi dimension arrays For instance a double subscripted array is referred to like this NUMBER 1 3 or NUMBER X Y Arrays may be any number of levels deep within memory limits but practicality dictates a reasonable limit The amount of memory you have dictates how much data you can store in an array At no time may the number of subscripts vary in any of the references to an array For example you cannot define an array as AS 10 20 and then refer to it in this manner READ A 1 2 5 The number of subscripts in each element reference must also match the number of subscripts in the corresponding MAP or DIM statement that defined the array size See Chapter 9 for more information on the DIM stat
358. ting Program Files Page 5 9 DEFINE FLAG 1 IFDEF FLAG section of AlphaBASIC PLUS code ENDIF The section of code following the IFDEF flag is compiled if FLAG is defined as anything 5 4 3 PRAGMA Setting Compiler Options PRAGMA can cause the compiler to set or take a specified option There are two groups of PRAGMA settings command line switch settings and string work area settings 5 4 3 14 PRAGMA and Command Line Switches Instead of specifying certain compiler options on the command line PRAGMA settings can be used from within the source file This can be a lot more convenient during the program s maintenance life cycle The following PRAGMA settings correspond to command line switches PRAGMA Setting Command Line case insensitive Switch ERROR IF NOT MAPPED FORCE FN note apostrophe FORCE IEEE FORCE OLD ISAM FORCE SBR EXT FORCE 24BIT NO LINENUMBERS TIMESTAMP FEATURE LIFESIGN AlphaBASIC PLUS User s Manual Rev 03 Page 5 10 Chapter Five Notes 1 This PRAGMA can be put anywhere in the source file The setting will take effect from that point PRAGMA can be used multiple times in the same file 2 This PRAGMA can only be put in the file once at the top of the file before any object code is generated by the compiler 3 This PRAGMA option takes a list of comma separated decimal values to turn on a particular option See Appe
359. tion oooocoooccoooo 22 4 22 5 3 Set a Breakpoint oie sa0ve ers ess wank do ea 22 4 22 5 4 Clear a Breakpoint 0 00 es 22 4 22 5 5 Execute AMOS Command xiii da 22 5 22 5 6 Find a Specific Label Lct wg RAE ERES 22 5 220 7 Tapia Verb som dica RE AES ERES 22 5 22 5 8 TUMO TRAP dt soit e oi mete d NOME RR ERAS 22 5 22 5 9 Send Program Display to Another Terminal 22 6 22 5 10 Display File Channel Information o o oo 22 6 22 544 Print Error Value iue ee ew Re Rete AR 22 6 22 5 12 Print Information on All File Channels 22 6 22 5 13 Display Function Source Code suslsus 22 7 22 5944 TIndent Texts e iem Cem ie ee ROUES a 22 7 22 5 15 Display List of Labels 2 5 i ce me 22 7 22 5 16 Change a Variable Value ooooooooooooo 22 7 22 5 17 Re Start Debugging sllslseleselleseslssss 22 8 22 5 18 Run Program From Program Pointer 22 8 22 5 19 Exit Debugger 255a eri oie RI em DS M ix 22 8 22020 Cleat ENON aaa PINE tue once d RU 22 8 22 5 21 Clear Error and Resume Execution liuius 22 8 22 59 22 SSCL Scale Factor soc ex etx REM d 22 8 22 5 28 Set Significance Value ooooooooommmmmm o 22 8 22 5 24 Break on Value Change llseslulseseseslsss 22 9 22 5 25 Remove Tracepoint y asse p RES XE PAD 22 9 22 5 26 Display List of Variables o oocooccoocccooooo 22 9 22 5 27 Break a
360. tion from main menu GOSUB DAY END Do End of day Processing GOSUB FINISH UP Finish up close files and exit END The subroutines start here INIT PRINT This section will initialize files AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 11 RETURN MENU PRINT This section will display the main menu and PRINT ask user for selections RETURN DAY END PRINT This section will do day end processing RETURN FINISH UP PRINT This section will close files and clean up final data RETURN You can nest subroutines For example PRINT Main Program GOSUB OUTER MOST OUTERMOST calls PRINT Return from Outermost NEXTMOST and INNERMOST OUTER MOST RETURN PRI GOS PRI NEX CNN NT Outermost subroutine UB NEXT MOST NT Return from Nextmost T MOST RINT Nextmost subroutine OSUB INNER MOST RINT Return from Innermost URN CI R MOST PRINT Innermost subroutine ETURN The program above prints Main Program Ou Re Nex R Ret tur termost subroutine tmost subroutine Innermost subroutine eturn from Innermost urn from Nextmost n from Outermost that subroutine rather than using a GOTO statement m It is good programming form to exit a su
361. tive of the numbers For example if you use B EDIT A 6 it does both 2 and 4 take out spaces tabs and excess Characters AlphaBASIC PLUS User s Manual Rev 03 Page 10 6 Chapter Ten Note AlphaBASIC PLUS processes these in order EDIT 2 first then EDIT 4 Also a string is not considered to have trailing spaces or tabs if a carriage return CR is at the end of the string If you use an odd number it is rounded down to the next even number since there is no EDIT code 1 For example READY STRSIZ 50 ETA Test String This is a string with spaces n PRINT EDIT Test String 2 Thisisastringwithspaces Do not use values above 63 they won t cause any harm but could make your program work incorrectly in the future if the list of EDIT codes is expanded 10 3 3FILL A L Copies an expression or part of an expression to a certain length If a numeric expression is given it is first converted to a string The format is FILLS expression length For example READY SIGNIFICANCE 15 tuy A XX ETA PRINT FILLS A 14 You may need to adjust the String Work Area size if you use FILL See the section Setting the String Work Area in Chapter 8 for details 10 3 4INSTR X A B Performs a search for the substring B within the string A beginning at the Xth character position It returns a numeric value of zero if B is not in A at or after the Xth position or the character position
362. to expand the file record size to 120 bytes and that most of the programs do not have to make use of the extra 20 bytes until some time in the future You write a program which copies the 100 byte record file into a new 120 byte record file and then you update the main parameter file to indicate the new record size for the vendor file is 120 bytes instead of 100 Each program now opens the file using the new 120 byte record size since it is read in from the parameter file at run time but only READs or WRITEs the first 100 bytes of each record due to the variables used by the READ READL WRITE and WRITEL calls 15 5 3Accessing Random Files The following sections show you the normal procedure for using Random files for each type of access USING RANDOM FILES IN RANDOM MODE 1Use the LOOKUP command to see if the file already exists If it does skip down to step 3 21f the file doesn t exist create it First decide the size of the logical records in decimal bytes Then compute the blocking factor as discussed above Use ALLOCATE to create the file with the number of disk blocks needed AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 7 3Use the OPEN statement to open the file for RANDOM processing Specify the size of the logical records in the file and the record number variable holding the number of the logical record you are currently accessing The file is open for exclusive access You may wis
363. to the MAP statement and executing it again remember you can t define the same variable twice in the same program Note if you omit the size parameter such as for floating point variables but you use the value parameter there must be an extra comma to indicate the missing size parameter MAP EI E 341415926535 MAP HOLIDAY S CHRISTMAS The first example preloads the value 3 1415926535 into the floating point variable called PI The second example preloads the letters CHRISTMAS into the string variable called HOLIDAY 14 2 60Origin In some instances it may be desirable to redefine records or array areas of different formats so they occupy the same memory area For instance a file may contain several different record formats with the first byte of the record containing a type code for that record format The origin parameter allows you to redefine the record area in the different formats to be expected When the record is read into the area the type code in the first byte can be used to execute the proper routine for the record type Each different routine can access the record in a different format by the different variable names in that format All record formats actually occupy the same area in memory This feature is much like the REDEFINES verb in the COBOL language data division Using the origin parameter can save large amounts of memory For instance suppose you have three very large variables of 256
364. to the common rules listed above eA label must be the first item on a line apart from an optional line number eA label must be terminated by a colon without any intervening spaces The colon is used when defining the location of the label it is not used when referring to the label 6 1 1 3User Defined Function Names User defined functions are discussed in Chapter 20 A user defined function name must obey the following rule in addition to the common rules listed above eit must begin with the characters FN or FN if the program is compiled with the F switch eOptionally the last character of the user defined function name can be either a or a to designate the type of the return value A dollar sign signifies a string return value a percent sign signifies a four byte true integer return value and neither one being present signifies a floating point return type 6 1 2External Assembly Language Subroutine XCALL Names External assembly language subroutines are discussed in Chapter 19 The name of the routine must obey these rules eThe name must be one to six characters long eThe name can consist of any combination of letters A through Z and the numbers O through 9 eUppercase and lowercase letters are identical 6 1 3Subprogram Names Subprogram names follow the same rules as external assembly language subroutine names AlphaBASIC PLUS User s Manual Rev 02 Page 6 4 Chapter Six 6 2VARIABLE TYPES AlphaBA
365. top status line without address End status line all kinds Select unshifted status line without address Select shifted status line without address Select black text Select white text Select blue text Select magenta text Select red text Select yellow text Select green text Select cyan text Select black reverse text Select white reverse text Select blue reverse text Select magenta reverse text Select red reverse text Select yellow reverse text Select green reverse text Select cyan reverse text Save a rectangular area Restore a rectangular screen area Enter full graphics mode Exit full graphics mode Draw a box with rounded corners Draw a window style box Draw a box with double lines Enable proportionally spaced text Disable proportionally spaced text Select color palette by RGB value Enable graphics cursor Disable graphics cursor Select graphics cursor shape Include graphics cursor location AlphaBASIC PLUS User s Manual Rev 02 Screen Handling Codes TCRT CODE 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 Page D 5 FUNCTION Define graphics cursor regions Output form feed character Output line feed character Output new line character Output vertical tab character Output plus or minus character Output greater than or equal character Output less than or equal character Output not equal character
366. tre sve bees 16 9 16 2 5 Error Handling in Subprograms o oococcococcc eee ee 16 9 16 2 6 Using Subprogram s s a be 16 10 16 2 7 Saved Runtime Environment oooccoccocooo o 16 11 CHAPTER 17 ERROR TRAPPING 17 1 WHAT IS ERROR TRAPPING lt a ao 17 1 17 2 THE ON ERROR GOTO STATEMENT 000 e eee 17 1 173 BRA FUNCION 2 as teen a a ete 17 2 17 3 1 Error Codes Returned by ERR 0 oooocococcocooo o 17 2 17 4 THE RESUME STATEMENT e nbckneveremr e m ka ie 17 3 17 5 CONTROLE TRAPPING 2 ari e 17 4 17 6 A SAMPLE ERROR RECOVERY ROUTINE oooo oo 17 4 AlphaBASIC PLUS User s Manual Rev 04 Page viii CHAPTER 18 EXTERNAL ASSEMBLY LANGUAGE SUBROUTINES 18 1 WHY USE ASSEMBLY LANGUAGE SUBROUTINES 18 2 AUTOMATIC SUBROUTINE LOADING CHAPTER 19 USING ISAM PLUS FILES 19 4 WHAT IS ISAM PLUS 19 2 ISAM PLUS FILE STRUCTURE 19 3 UPDATING THE RECORDS OF AN ISAM PLUS FILE 19 3 1 OPEN Statement for ISAM PLUS Files 19 3 2 GET GETLOCKED and GETREAD ONLY Table of Contents Vui estu ei a Rua i 19 3 19 3 3 GETNEXT GETNEXT LOCKED and GETNEXT READ ONLY 19 4 19 3 4 GET PREV GETPREV LOCKED and GET PREV READ ONLY 19 4 19 3 5 FIND FIND NEXT and FINDPREV 19 5 19 3 6 UPDATERECORD eee 19 5 19 3 7 CREATERECORD eh 19 6 19 3 8 DELETERECORD seh 19 6 19 3 9 RELEASE RECORD
367. true integer variable In addition to the usual difference of the interpretation of the high order bit as either a numeric value or a sign bit the order of the two words comprising the longword value is swapped from native ordering AlphaBASIC PLUS deals with this difference transparently It is only evident when data is written to an external medium and read by a non AlphaBASIC PLUS or AlphaBASIC program or when data is passed to or from an assembly language subroutine 6 2 1 1 30ther Integer Representations There is also a special format for character constants and alternate radix constants that specify integer constants which is detailed in a section below These constants behave identically to true integers The characteristics of the various integer data types are summarized below AlphaBASIC PLUS User s Manual Rev 02 Page 6 6 Chapter Six Type MAP Signed Minimum Value Maximum Value 255 65 535 16 777 215 4 294 967 295 549 755 813 888 549 755 813 887 Integer 128 127 32 768 32 767 2 147 483 648 2 147 483 647 6 2 1 2Real Numbers Real numbers ones with a decimal fraction come in two styles 6 byte AMOS floating point numbers el byte single precision and 8 byte double precision IEEE floating point numbers 6 2 1 2 1AMOS Floating Point Numbers AMOS floating point numbers are manipulated by software and are generally not comprehensible to non AMOS systems without first being converting to another fo
368. ual Rev 03 Page J 2 Appendix J You can also embed the option list inside the source file by using a PRAGMA command This saves you from having to remember to use the right option switches on the right files at every compilation The PRAGMA statement see Chapter 5 for more details corresponding to the command line is PRAGMA FEATURE 1 3 6 COMPLP will check that it understands and can act on each of those options in turn aborting if it cannot do so It will compile the file taking the appropriate option actions and produce the output object file MYFILE RP The compilation statistics will list the options selected In addition COMPLP will encode and write the option list 1 3 6 into MYFILE RP for RUNP to take action on This allows MYFILE to be invoked without any additional command line switches and is a safety check in case MYFILE RP is transfered to a system that has a version of RUNP that cannot understand one or more of the options When RUNP executes the file it will check to see if options have been selected If so it will check to see if it understands and can take the appropriate action If it cannot RUNP will fail with a non trappable runtime error J 3CHECKING AVAILABILITY OF OPTIONS You can see which options your version of COMPLP understands by using the R switch COMP LP R ETA This lists all the options COMPLP understands RUNP offers the same option RUNP R GETUN You can see which options h
369. ulfilled 2 expected Adjust your code so the expected condition is fulfilled or y expected You left off a comma or a parenthesis Correct the line and try again z expected You left out an equal sign Correct the line and try again expected expected You left out a parenthesis Correct the line and try again Array expected Adjust your code so the expected condition is fulfilled ARRAYS cannot have initializers Check your code and the format for the array and try again AlphaBASIC PLUS User s Manual Rev 02 Page A 2 Appendix A Bad format in conditional compilation directive A IF IFDEF or IFNDEF line is not in the correct format See section 5 3 for the correct format Bad PRAGMA option The word after PRAGMA is not a legal option See section 5 4 for the valid options Bad PRAGMA option value The value you were setting for the option is illegal Each option has its own legal range of values See section 5 4 for details Bad option set number n in PXn option The value on n you supplied is invalid See Appendix for details Bad symbolic key variable not mapped in ISAM code 7 The symbolic key you specified in an ISAM code 7 statement is not a simple variable It must be mapped non subscripted not a parameter and not an expression for example a substring or concatenation Bitmap kaput Your program attempted a file operation OPEN ALLOCATE etc on a device with a
370. uous file in all cases Remember the number returned by LOOKUP is the physical disk blocks used by the file Multiply this number of 512 byte blocks by the file s blocking factor to find out how many logical records the file contains For example after you do LOOKUP PAYROL DAT BLOCKS AlphaBASIC PLUS User s Manual Rev 02 Page 15 16 Chapter Fifteen the variable BLOCKS contains the number of disk blocks in the file PAYROL DAT or a 0 if the file does not exist For example say that BLOCKS 40 and the blocking factor for the file is 4 Multiplying 40 by 4 gives you 160 logical records There are two optional switches with LOOKUP The default switch is O When this switch is in effect LOOKUP searches for the file first in your current account then in your x 0 account For example if you are logged into account 100 3 LOOKUP looks for the file in 100 3 ana if it doesn t find it looks in 100 0 If K is used LOOKUP only searches for the file in the current account This switch is provided to prevent a problem that can occur when using LOOKUP and KILL on the same file Because of the AMOS file protection system KILL can only erase a file from your current account If the file exists only in your x 0 account you could find it with LOOKUP but your program could not KILL the file and you see an error If you are using LOOKUP for the purpose of identifying a file to be erased use K With K any file found by LOOKUP
371. us equals 1 or if you didn t specify status your program ends and you see an AMOS error message explaining the file doesn t exist Some examples R ENAME payrol dat TO payrec old status ENAME NEW DATA REPORTS WAVE LENGTHS FI R ENAME The standard LE Data log TO a status of renan ne AMOS rules apply you can t rename files on different devices or in accounts with a different project number than the one the program is running in There is also a RENAME function see Chapter 11 9 38REPEAT Starts the next iteration of a loop structure REPEAT can be used within FOR NEXT or DO LOOP structures to cause control to pass to the NEXT or DO statement so the loop begins again For example AlphaBASIC PLUS User s Manual Rev 02 Program Statements Page 9 27 DO WHILE X lt 100 X X gt 3 A IF X gt 5 THEN X X B REPEAT ENDIF X X C LOOP In the above case REPEAT causes the statement x x Cto be skipped if x gt 5 9 39RESTORE See READ RESTORE AND DATA above 9 40RESUME See ON ERROR AND RESUME above 9 41RETURN See GOSUB OR CALL AND RETURN above 9 42SCALE The format is SCALE value The scaling factor represents the number of decimal places the digit window is effectively shifted to the right or left in any floating point number SCALE is discussed
372. ust as if the file had been typed in from your terminal If you want to load in a complete program use the NEW command prior to any LOAD command to make sure memory is clear If you don t the contents of a program in memory may mix with the program you are loading Here are two examples of LOAD READY LOAD NEWBAS UN READY LOAD DSK2 PWRS2 BP 50 1 READY AlphaBASIC PLUS User s Manual Rev 02 Page 4 4 Chapter Four 4 5THE SINGLE STEP FEATURE The single step function is a feature not found in many versions of BASIC and is useful in debugging programs and in teaching the principles of BASIC programming to people who are new to BASIC Once you have a program or even part of a program in memory you can use the single step command by pressing J the LINEFEED key sometimes labeled LF When you press J the next line of the program displays on your terminal and then executes Here is an example LIST tUm 10 CONSTANT 7 20 FOR I 1 to 2 30 PRINT INPUT Enter a number NUM 40 VALUE VALUE CONSTANT NUM 1 50 NEXT I 60 PRINT VALUE READY y COMPILING Compile time was 0 21 seconds elapsed time was 1 seconds 10 CONSTANT 7 Vv 20 FOR I 1 to 2 Vv 30 PRINT INPUT Enter a number NUM Enter a number 4 EA bd 40 VALUE VALUE CONSTANT NUM I PRINT VALUE EU 10 v 50 NEXT I bd
373. variable only picks up the first ten characters of the string If STRSIZ is set to 40 you see the second display To read the data above as three separate pieces of string data you must remember to separate the data by explicitly placing commas into the file For example AlphaBASIC PLUS User s Manual Rev 02 The File Input Output System Page 15 13 PRINT 100 HELLO AGE DATE sends this to the file HELLO AGE DATE which are input correctly by the following statement INPUT 4100 A B CS Note the statement PRINT 100 HELLO AGE DATE improperly formats the data in the file because the unquoted commas above cause PRINT to separate the data with spaces as well as commas HELLO AGE T DATE Using semi colons instead of the unquoted commas solves this problem For example PRINT 4100 HELLO AGE DATE 15 9 7INPUT LINE After a sequential file has been opened for input the data can be read from the file by a special form of the INPUT LINE statement which uses a file channel number corresponding to the file channel assigned in the OPEN statement The variable may be either numeric or string but should follow the format of the data in the file being read String variables accept numeric data but if you try to read string data into a numeric variable the numeric variable equals 0 The general format is
374. vice to see if the appropriate buttons are pushed plugs are in etc Disk not mounted The specified disk has not been mounted Mount it by using the MOUNT monitor command or by using the XMOUNT subroutine Division by zero Your program attempted to perform a division by zero Check the values that went into the equation You may want to install a check for zero values or use an error trapping routine to catch zero divisions Duplicate label Your program has defined the same label name more than once Search the BP file for the duplicate labels and change one of them to a unique name Duplicate line number Change one of the duplicate line numbers Duplicate SUBPROGRAM name Change one of the SUBPROGRAM names End of Program You have reached the end of the program during single stepping in Interactive Mode If you press the line feed key again your program restarts at the beginning ENDFN without DEF Add an ENDFN statement to finish the function definition Enter CR to continue You have reached a STOP statement in your program You may continue from the STOP statement by pressing EWN or you may abort the run by pressing c amp J Error during error trapping An error occurred while you were in the error trapping routine Check your routine for incorrect statements or mis spellings AlphaBASIC PLUS User s Manual Rev 02 Messages Page A 7 2Error writing to output file Make sure the disk is
375. vious record in key order into the record buffer The key number used is from the last GET or FIND The format is GET PREV f ile channel WAIT RECORD varlist AlphaBASIC PLUS User s Manual Rev 03 Using ISAM PLUS Files Page 19 5 19 3 5FIND FIND NEXT and FIND PREV These statements are similar to GET and GET NEXT statements The difference is FIND does not transfer data from the file to memory It positions the current record pointer so a GET or GET NEXT retrieves the record specified by the FIND FIND NEXT or FIND PREV statement The FIND statements may also be used to obtain the relative record number associated with a given key The format is FIND file channel ISAM KEY knum rel kval retkey FIND NEXT file channel r FIND PREV file channel r tkey tkey See the GET section above for definitions of the elements of the statement The argument retkey is the variable which contains the key of the located record It is assumed the retkey variable is of the correct type and size to receive the key The status values assigned to the file s status variable are defined as ISAM NF 3 Key not found ISAM LT 1 Found key with lesser value ISAM EQ 0 Found key with equal value ISAM GT 1 Found key with greater value If the key is found the relative record number variable is updated FIND NEXT and FIND PREV return these status values in t
376. x Binary format conversion E 3 Binary variables sist rs rie 14 5 Blank Spaces y musica 10 9 Blocking TACO E nec eee Es 15 5 Bb Mr tere ro El eres A uM de 18 1 Brariching 26k hi litis wey DIA ne 9 21 BREAK Sapo ay aabt died 4 1 22 4 Breakpoint erede A 22 4 Breakpoints 000 eee ee 3 1 4 1 4 5 BYE its ae 3 2 3 9 BYTEDO wr Este vol mE esi hes 11 1 CAUCE La ERROR Ie 9 2 9 9 9 20 Carriage return linefeed 9 23 CASE casa eke a FS PE 9 2 A A Ee vicc WR SER e linde E 9 2 15 9 16 1 22 9 Chaining to system functions 16 2 CHANNEL Aoc s Cte cree e sura de CEA a 22 6 Character constants o o o 6 10 OT A ee ed S laa Sah eld aye at ee 10 5 A A dee 22 4 Clearing interactive memory 3 3 Glock lICKS n er ERES 11 4 CLOSE rgi Ladi bx aul be b de 15 10 19 7 GLOSEK occitano 15 10 19 7 Closing an ISAM PLUS file 19 7 CMDLIN 422 Let adea s t RI eR 10 11 Colon symbol seesslssss 3 3 Comma symbol j ooo o ooooo 8 1 9 22 Command files 16 2 Comments ems o ores LU mE de EE Kc 2 2 COMMON 12522 A5RES ARIS ARBRES SS 9 3 16 2 Compilation control 5 5 Compiler options 5 3 Compiler options interactive mode 3 8 Compiling a program o o o o 3 7 5 8 COMP UR eret ers dr pt Uode 1 5 2 4 5 3 OPIO aora rs 5 3 6 12 GCOMPEPIETE v a Das tara eate tee
377. xecutes again If you single step a statement asking for input from the terminal enter the input and press as we did in the example above Then you may proceed to the next statement by pressing J again AlphaBASIC PLUS User s Manual Rev 02 CHAPTER 5 WRITING PROGRAM FILES In this chapter we discuss eUsing AlphaXED or AlphaVUE to create a program eThe form of an AlphaBASIC PLUS program eCompiling a program eRunning a program Although interactive mode has many good features the true power of AlphaBASIC PLUS is in using AlphaXED COMPLP and RUNP to create compile and run your programs as disk files 5 1CREATING A PROGRAM There are two ways to create a source program using interactive mode to type in the program save the program on disk and then exit BASICP or using AlphaXED or AlphaVUE The easiest way to create a program to be compiled with COMPLP is to use AlphaXED to create the source file which usually has a BP extension AlphaXED is a screen oriented program editor that lets you see your program on the terminal screen as you type it in You can move the cursor around on the screen and change or delete text at the current cursor position It also has unique features designed especially to aid programmers in writing programs See your AlphaXED User s Manual if you are not familiar with AlghaXED AlphaVUE can also be used 5 2PROGRAM FORM The form your program takes may differ somewhat depending on whether you use
378. your record size does not divide evenly into 512 bytes it is a good idea to consider expanding it so it does This leaves you room for future expansion of the data in the record You use the same number of physical disk blocks whether or not you expand the record size so you do not save anything by not doing so When you are opening a random file you must specify the logical record size and the record number in the OPEN statement also specifying RANDOM or RANDOM FORCED mode it is possible to get your data misinterpreted if you do not have the record size correct No logical record size is maintained within the file structure itself This fact does make it nice in one respect a file which is accessed by many programs can have its record size expanded without recompiling all the accessing programs Here is how it works Assume as an example you have a file which is considered the parameter descriptor file for all other files in the entire system This file gives the record size as 100 bytes for the vendor name and address file All programs which refer to the vendor file first read this parameter file to get the size of the vendor file logical record The programs then set the size into a variable and use this variable in the OPEN statement for the record size Each READ READL WRITE or WRITEL statement then manipulates the 100 bytes of data by reading or writing to or from variables whose size totals 100 bytes Let s say you now want

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