- print_r: documentation ( source)
<?php
$a = new \Datetime("2015-12-03");
$b = new \Datetime("2015-12-12");
print_r($b->diff($a)->format("%y - %m - %d")). "\n";
$now = new DateTime;
$clone = clone $now;
$clone->modify( '-1 day' );
echo $now->format( 'd-m-Y' ), "\n", $clone->format( 'd-m-Y' );