Calculating the difference between two dates using PHP

To find out the difference between two dates use the class DateTime: 

$startDate = new DateTime( '2007-03-24 15:40:10' );
$endDate = new DateTime( '2009-07-12 17:56:20' );
$interval = $startDate->diff( $endDate );
echo 'Difference: ' . $interval->y . ' years, ' . $interval->m . ' months, ' . $interval->d . ' days, ' . $interval->h . ' hours, ' . $interval->i . ' minutes, ' . $interval->s . ' seconds';

The result:

Difference: 2 years, 3 months, 18 days, 2 hours, 16 minutes, 10 seconds