Description:
------------
It would be nice to mention that fwrite - here after fopen('w') - moves 
the pointer. So two times writing results in appending what is written, 
not replacing.

Reproduce code:
---------------
<?php
$datei = 'test.txt';
$dh = fopen($datei,'w');
flock($dh,LOCK_EX);
fwrite($dh,'1');
fwrite($dh,'23');
fclose($dh);
?>

Expected result:
----------------
Content of test.txt:

23

Actual result:
--------------
Content of test.txt:

123