yyyymmdd to yyyy-mm-dd php

$date = DateTime::createFromFormat('d/m/Y', "24/04/2012");
echo $date->format('Y-m-d');

<?php
// both lines output 813470400
echo strtotime("19951012"), "\n",
     strtotime("12 October 1995");

// prints 1995 Oct 12
echo date("Y-m-d", strtotime("19951012"));
?>