Difference Between Two Dates Using PHP

Use this code for the difference between two dates:

$date1 = '2012-12-12';
$date2 = '2012-12-20';

$start_date = strtotime($date1);
$end_date = strtotime($date2);

echo ($end_date - $start_date)/60/60/24;

Simple like that:

$start_date = strtotime('2012-12-12');
$end_date = strtotime('2012-12-20');

echo ($end_date - $start_date)/60/60/24;