- var_dump: documentation ( source)
<?php
$date = new DateTime('first day of previous month 00:00:00', new DateTimeZone('UTC'));
var_dump($date->format('Y-m-d H:i:s')); // string(19) "2013-11-01 00:00:00"
$date = new DateTime('first day of previous month 00:00:00', new DateTimeZone('Europe/Amsterdam'));
var_dump($date->format('Y-m-d H:i:s')); // string(19) "2013-11-01 00:00:00"
$date = new DateTime('midnight first day of previous month', new DateTimeZone('Europe/Amsterdam'));
var_dump($date->format('Y-m-d H:i:s')); // string(19) "2013-11-01 00:00:00"
$date = new DateTime('midnight first day of previous month', new DateTimeZone('UTC'));
var_dump($date->format('Y-m-d H:i:s')); // string(19) "2013-11-01 00:00:00"