PHP date calculation

Question

What is the best (date format independent way) in PHP to calculate difference in days between two dates in specified format.

I tried the following function:

Answer 1

PHP 5.2 introduces the DateTime and DateInterval classes which makes this easy:

function get_date_offset($start_date, $end_date)
{
    $start_time = new DateTime($start_date);
    $end_time   = new DateTime($end_date);
    $interval   = $end_time->diff($start_time);
    return $interval->format('%a days');
}