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Seeks on a file pointer (PHP 4, PHP 5)
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.



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


The offset.

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


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.


Example 648. fseek() example


= fopen('somefile.txt', 'r');

// read some data
$data = fgets($fp, 4096);

// move back to the beginning of the file
// same as rewind($fp);
fseek($fp, 0);




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.


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).