Resta fechas en PHP Formato YYYY-MM-DD

gistfile1.php

<?php
function restafechas($startDate,$endDate){

  list($year, $month, $day) = explode("-", $startDate);
	$startDate = mktime(0, 0, 0, $month, $day, $year);

	list($year, $month, $day) = explode("-", $endDate);
	$endDate = mktime(0, 0, 0, $month, $day, $year);	

  $totalDays = ($endDate - $startDate)/(60 * 60 * 24);
	
return $totalDays;
}

?>