SEEK statement

Purpose

Set the position in a file for the next input or output operation.

Syntax

SEEK [#] filenum&, position&&

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.

See also

EOF, FILEATTR, GET$, LOC, LOF, OPEN, PUT$, SEEK functionSETEOF

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