- print_r: documentation ( source)
<?php
$di = (new DateTime('2012-10-20'))->diff(new DateTime('2012-12-10'));
print_r($di);
print_r((new DateTime('2015-09-30'))->add($di));
$di2 = (new DateTime('2015-09-30'))->diff(new DateTime('2015-12-06 22:23:00'));
print_r($di2);