- var_dump: documentation ( source)
<?php
$serviceStart = new DateTime('8/20/2012');
$serviceEnd = $serviceStart->modify('+2 years');
$diff = $serviceStart->diff($serviceEnd);
var_dump($diff->format('%a'), $serviceStart, $serviceEnd);
$serviceStart = new DateTime('8/20/2012');
$serviceEnd = (new DateTime('8/20/2012'))->modify('+2 years');
$diff = $serviceStart->diff($serviceEnd);
var_dump($diff->format('%a'), $serviceStart, $serviceEnd);