Get difference of two times

Question

I use below code to get difference of start time and end time.
$totalTime = strtotime($endTime)-strtotime($startTime);
But some time it return 00:00:00
Why this happens? Please help.

Answer 1

in PHP 5 and up you can use:

<?php
$date = new DateTime('2000-01-20');
$date->sub(new DateInterval('P10D'));
echo $date->format('Y-m-d') . "\n";
?>