- abs: documentation ( source)
- floor: documentation ( source)
- strtotime: documentation ( source)
- printf: documentation ( source)
<?php
$date1 = "2007-03-24";
$date2 = "2009-06-26";
$diff = abs(strtotime($date2) - strtotime($date1));
$days = floor(60*60*24);
printf("%d years, %d months, %d days\n", $years, $months, $days);