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Purpose |
Set the position in a file for the next input or output operation. |
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Syntax |
SEEK [#] filenum&, position&& |
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Remarks |
SEEK sets the file pointer position of file filenum& to position&&. position&& is a Quad-integer variable, constant, or expression. The next GET$ or PUT$ performed on the file filenum& will occur position&& bytes (or records) deep into the file. If file filenum& was opened in binary or sequential mode, position&& indicates the new file position in bytes; for random-access files, position is in records. The first byte position (for binary and sequential files) or record position (for random-access files) may be 0 or 1, depending on the BASE option used when the file was initially Opened. If no BASE was specified, the default position is 1. Use the SEEK function to determine a binary file's current pointer position, and LOF to determine its length. Seeking past the end of a file does not produce an error, but no data can be read from beyond the true end of the file. |
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See also |
EOF, FILEATTR, GET$, LOC, LOF, OPEN, PUT$, SEEK function, SETEOF |
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Example |
SUB CreateFile ' Open a binary file and writes 75 chars to it. LOCAL I& OPEN "SEEK.DTA" FOR BINARY AS #1 FOR I& = 48 TO 122 PUT$ 1, CHR$(I&) NEXT I& END SUB
FUNCTION ReadIt$(Start&&, qSize&&) ' SEEK to the correct position in the file, ' which was previously opened in the CreateFile SUB. SEEK 1, Start&& I&& = 1 TempStr$ = "" ' Read in the indicated data - don't read past end of file. WHILE (ISFALSE EOF(1)) AND (I&& <= qSize&&) GET$ 1, 1, Char$ TempStr$ = TempStr$ + Char$ INCR I&& WEND ReadIt$ = TempStr$ ' assign function's result END FUNCTION |