Below is something I try that ofcourse not work because of rsosort. Here is my code: ----------------------- $lagret_dato = $_POST['lagret_dato']; foreach($lagret_dato as $dag){ $dag = explode("/", $dag); rsort($dag); $dag = implode("-", $dag); var_dump($dag); What I want is a way to rewrite contents of a variable like this: >From 24/7/2013 to 2013-07-24 Is there a way in PHP to do this? Thank you very much. Karl