REM FILEDEMO.ASI

REM This is an ASIC demo program which illustrates how to perform various file
REM operations.

REM Part I - Creates an ASCII file easily readable by GWBASIC/BASICA and others 
REM Part II - Reads an ASCII file with strings delimited by CR/LF
REM Part III - Creates a 5 record random file and allows you to display and
REM            update any record.
REM Part IV - Appends a record using the OPEN statement with Append option
REM Part V  - Appends a record to a file OPEN in random I/O mode ("R")
REM           and then lists all records in the file.

REM Note:  This sample code does not check the ERROR system variable after
REM        most OPEN/CLOSE/INPUT#/PRINT# statements.  However, when writing
REM        "real" programs you should always add a statement to check for
REM        errors, such as "IF ERROR>0 THEN PROCESSERROR:" after EVERY
REM        OPEN/CLOSE/INPUT#/PRINT# statement.


REM Part I - Creating a file readable by GWBASIC/BASICA and other programs.
REM Write file FILEDEMO.001 with a string and integer delimited by comma,
REM with a carriage return/line feed sequence at the end
CR$=CHR$(13)
LF$=CHR$(10)
CRLF$=CR$+LF$
OPEN "O", 1,"FILEDEMO.001"
APPLES=100
PRINT #1, "Apples" NONULL
APPLES$=STR$(APPLES)
PRINT #1,"," NONULL
PRINT #1, APPLES$ NONULL
PRINT #1, CRLF$ NONULL
CLOSE 1

REM Part II - Reading a "normal" ASCII DOS file (CR/LF delimited).
REM Reads FILEDEMO.001 which was written in part I, and displays it's contents. 
OPEN "I", 1, "FILEDEMO.001"
INPUT #1,APPLES$ CRLF
PRINT APPLES$
CLOSE 1

REM PART III - Using a random file
REM  Create a file FILEDEMO.002
OPEN "O",1,"FILEDEMO.002"
REM Create five "records" with a single integer field, set initial values 1-5.
REM File is written in normal ASIC format for integers (2 binary bytes).
FOR I=1 TO 5
   PRINT #1,i
NEXT I
CLOSE 1
REM Process FILEDEMO.002 randomly
REM Prompt for a record to modify, show the current value, accept a new value
REM from the user, and then write the new value.
OPEN "R",1,"FILEDEMO.002"
GETRECNO:
   PRINT "ENTER RECORD # TO MODIFY";
   INPUT RECNO
   IF RECNO<1 THEN
       PRINT "RECORD # MUST BE GREATER THAN 0"
       GOTO GETRECNO:
   ELSE
       IF RECNO>5 THEN
           PRINT "RECORD # MUST BE LESS THAN 5"
           GOTO GETRECNO:
       ENDIF
   ENDIF
FILEOFFSET=RECNO*2
FILEOFFSET=FILEOFFSET - 2
REM FILEOFFSET NOTES:  In this example, each record contains one integer field
REM that is two bytes long.  Must subtract two since first record starts at
REM offset=0.
NEWPOS=FILEPOS(1,FILEOFFSET)
INPUT #1, VALUE
PRINT "CURRENT VALUE IS ";
PRINT VALUE
PRINT "ENTER NEW VALUE ";
INPUT VALUE
NEWPOS=FILEPOS(1,FILEOFFSET)
PRINT #1, VALUE
CLOSE 1

REM PART IV - Append a record to the random file FILEDEMO.002
REM Append option 1 - Use OPEN with the "A" option if the file is not open.
REM Add record #6 with a value of 99
OPEN "A",1,"FILEDEMO.002"
PRINT #1, 99
CLOSE 1

REM Append option 2 - If file is already open random ("R"), use the file pos to 
REM move to the end of the file, and then write the record
REM add record # 7
OPEN "R",1,"FILEDEMO.002"
X=FILEPOS(1,EOF)
PRINT #1, 999

REM Now position file to beginning, and display all values by reading file
REM sequentially
NEWPOS=FILEPOS(1,0)
RECNO=0
READALL:
   INPUT #1,VALUE
   IF ERROR>0 THEN
       PRINT "File Status = ";
       PRINT ERROR
       PRINT "Records Read = ";
       PRINT RECNO
       CLOSE 1
       GOTO EXIT:
   ENDIF
   RECNO=RECNO+1
   PRINT "Record # ";
   PRINT RECNO;
   PRINT " ";
   PRINT VALUE
   GOTO READALL:
EXIT: REM clean up disk
   PRINT "Do you want to delete the work files created by this program"
   print "'FILEDEMO.001 and FILEDEMO.002' (Y/N)";
   INPUT x$
   x$=UCASE$(x$)
   IF x$="Y" THEN
       KILL "filedemo.001"
       KILL "filedemo.002"
       PRINT "Work files deleted"
   ENDIF
   END