Forum und email

fseek

(PHP 4, PHP 5)

fseek — Seeks on a file pointer

Description

int fseek ( resource $handle , int $offset [, int $whence ] )

Sets the file position indicator for the file referenced by handle . The new position, measured in bytes from the beginning of the file, is obtained by adding offset to the position specified by whence .

Parameters

handle

A file system pointer resource that is typically created using fopen().

offset

The offset.

To move to a position before the end-of-file, you need to pass a negative value in offset .

whence

whence values are:

  • SEEK_SET - Set position equal to offset bytes.
  • SEEK_CUR - Set position to current location plus offset .
  • SEEK_END - Set position to end-of-file plus offset .

If whence is not specified, it is assumed to be SEEK_SET.

Return values

Upon success, returns 0; otherwise, returns -1. Note that seeking past EOF is not considered an error.

Examples

Example#1 fseek() example

<?php

$fp 
fopen('somefile.txt''r');

// read some data
$data fgets($fp4096);

// move back to the beginning of the file
// same as rewind($fp);
fseek($fp0);

?>

Notes

Note: If you have opened the file in append ("a" or "a+") mode, any data you write to the file will always be appended, regardless of the file position.

Note: May not be used on file pointers returned by fopen() if they use the "http://" or "ftp://" formats. fseek() gives also undefined results for append-only streams (opened with "a" flag).

See Also