- var_dump: documentation ( source)
<?php
$currentDate = new DateTime();
$targetDate = new DateTime('2015-03-05 11:11:11');
$interval = $currentDate->diff($targetDate);
// var_dump($interval); // Uncomment and isset will give the expected response
var_dump($interval->y);
var_dump($interval->m);
var_dump(isset($interval->y));
var_dump(isset($interval->m));