This module is part of the original MMBasic library. It is reproduced here with kind permission of Hugh Buckle and Geoff Graham. Be aware it may reference functionality which has changed or is deprecated in the latest versions of MMBasic.¶
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RANDOM.BAS
' Demonstration of random file access.
' Geoff Graham July 2013
'
' Using this program you can append to a file (to add some data in the first place)
' then read/write records using random record numbers. The first record in
' the file is record number 1, the second is 2, etc.
RecLen = 64
OPEN "test.dat" FOR RANDOM AS #1
DO
abort: PRINT
PRINT "Number of records in the file =" LOF(#1)/RecLen
INPUT "Command (r = read,w = write, a = append, q = quit): ", cmd$
IF cmd$ = "q" THEN CLOSE #1 : END
IF cmd$ = "a" THEN
SEEK #1, LOF(#1) + 1
ELSE
INPUT "Record Number: ", nbr
IF nbr < 1 or nbr > LOF(#1)/RecLen THEN PRINT "Invalid record" : GOTO abort
SEEK #1, RecLen * (nbr - 1) + 1
ENDIF
IF cmd$ = "r" THEN
PRINT "The record = " INPUT$(RecLen, #1)
ELSE
LINE INPUT "Enter the data to be written: ", dat$
PRINT #1,dat$ + SPACE$(RecLen - LEN(dat$));
ENDIF
LOOP