- var_dump: documentation ( source)
<?php
var_dump(\DateTimeImmutable::createFromFormat('Y-m-d', '2012-12-12'));
var_dump(\DateTimeImmutable::createFromFormat('Y-m-d', '2012'));
var_dump(\DateTimeImmutable::createFromFormat('Y-m-d', '0'));
var_dump(\DateTimeImmutable::createFromFormat('Y-m-d', '2000-0-0'));