- date_diff: documentation ( source)
- date_create: documentation ( source)
- date_interval_create_from_date_string: documentation ( source)
- date_sub: documentation ( source)
<?php
$products_date_added = date_create('2015-09-25');
$ndate = date_create();
date_sub($ndate, date_interval_create_from_date_string("30 days"));
echo $ndate->format("Y-m-d");
$diff = date_diff( $products_date_added, $ndate );
echo $diff->format("%a");
?>