OPENIN Function

OPENIN(string-expression)

Opens a file for input (reading only). Returns an integer file handle that must be used with READ$ and CLOSE.

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Examples

REM Open a file for reading
fh = OPENIN("/data/example.txt")
IF fh < 0 THEN
    PRINT "Failed to open file"
    END
ENDIF
 
REPEAT
    line$ = READ$(fh)
    IF EOF(fh) = 0 THEN PRINT line$
UNTIL EOF(fh) = 1
 
CLOSE fh

REM Handle missing file gracefully
fh = OPENIN("/notfound.txt")
IF fh < 0 THEN
    PRINT "File not found"
ELSE
    PRINT "File opened successfully"
    CLOSE fh
ENDIF

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Notes

• Returns a non-negative handle on success, or a negative value on failure.
• File handle must be closed with CLOSE when no longer needed.
• Works with EOF to detect end-of-file during reads.
• Use OPENOUT to create or overwrite files, and OPENUP to append to existing files.

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See also: READ$ · CLOSE · OPENOUT · OPENUP · EOF