- var_dump: documentation ( source)
- date_default_timezone_set: documentation ( source)
<?php
date_default_timezone_set('WST');
$d = new DateTime('2008-03-01');
$a = new DateTime('2018-03-01');
var_dump($d->diff($a)->y);
date_default_timezone_set('Europe/Amsterdam');
$d = new DateTime('2008-03-01');
$a = new DateTime('2018-03-01');
var_dump($d->diff($a)->y);