- var_dump: documentation ( source)
<?php
$foo = DateTime::createFromFormat('Y-m-d H:i:s', '2014-01-29 11:55:00');
var_dump($foo->getTimestamp());
$foo->setTimezone(new DateTimeZone('Europe/Vilnius'));
var_dump($foo->getTimestamp());
$bar = DateTime::createFromFormat('Y-m-d H:i:s', '1970-01-01 11:55:00');
$bar->setTimezone(new DateTimeZone('Europe/Vilnius'));
var_dump($foo, $bar, $foo->diff($bar));