- date_diff: documentation ( source)
- print_r: documentation ( source)
- strtotime: documentation ( source)
<?php
$t1 = strtotime('2013-10-01 00:00:00');
$t2 = strtotime('2013-11-01 00:00:00');
$i = date_diff(DateTime::createFromFormat('U', $t1), DateTime::createFromFormat('U', $t2), true);
print_r($i);