- var_dump: documentation ( source)
- preg_replace: documentation ( source)
<?php
$datetime = '2014-11-10-16.14.18';
$datetime = preg_replace('#(\d+)-(\d+)-(\d+)-(\d+)\.(\d+)\.(\d+)#', '\1-\2-\3-\4 ', $datetime);
var_dump($datetime);