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Seeks on a file pointer


fseek

(PHP 4, PHP 5)

fseekSeeks on a file pointer

Description

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

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 and set whence to SEEK_END.

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.

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

  • ftell() - Returns the current position of the file read/write pointer
  • rewind() - Rewind the position of a file pointer

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