- print_r: documentation ( source)
<?php
$date_start = new DateTime('2010-03-01');
$date_start->setISODate(2014,5,0);
$date_end = new DateTime('2010-07-29');
$date_end->setISODate(2014,5,3);
$interval = $date_start->diff($date_end);
print_r($interval);