Podręcznik PHP
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fseek

(PHP 3, 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, whose values are defined as follows:

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

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

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

Przykład 1. fseek() example

<?php

                

                $fp = 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);

                
?>

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).

Notatka: The whence argument was added after PHP 4.0.0.

Notatka: 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.