- var_dump: documentation ( source)
<?php
//Source: https://bugs.php.net/bug.php?id=67634
$date = new DateTimeImmutable('first day of next month midnight - 1 second');
var_dump($date->format('c'));
var_dump($date->format('U'));
var_dump($date->getTimestamp());
var_dump($date->format('c'));
var_dump($date->format('U'));