- var_dump: documentation ( source)
- date_default_timezone_set: documentation ( source)
<?php
date_default_timezone_set("UTC");
$dt1 = new DateTime("2012-06-25");
$dt2 = new DateTime("2012-07-27");
$dt3 = new DateTime("2012-07-02");
$iv = $dt1->diff($dt2);
var_dump($iv);
$dt4 = $dt3->add($iv);
echo $dt4->format("c");