- var_dump: documentation ( source)
- time: documentation ( source)
- date: documentation ( source)
- strtotime: documentation ( source)
<?php
$dayZ = "2013-10-25";
$dayZ = strtotime("monday this week", (!empty($dayZ)) ? strtotime($dayZ) : time());
var_dump(date("Y-m-d H:i:s", $dayZ));