- var_dump: documentation ( source)
<?php
// Works
$date = new DateTime('2013-12-27', new DateTimeZone('GMT'));
var_dump($date);
var_dump($date->modify('+1 day'));
// Doesn't work
$date = new DateTime('2013-12-27');
var_dump($date);
var_dump($date->modify('+1 weekday'));