(PHP 4, PHP 5)
fseek — Seeks on a file pointer
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.
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 values are:
Upon success, returns 0; otherwise, returns -1. Note that seeking past EOF is not considered an error.
Example #1 fseek() example
$fp = fopen('somefile.txt', 'r');
// read some data
$data = fgets($fp, 4096);
// move back to the beginning of the file
// same as rewind($fp);
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).