- error_reporting: documentation ( source)
- date: documentation ( source)
- strtotime: documentation ( source)
<?php
error_reporting(~0);
$timestamp_initial = strtotime('2013-12-17 10:08:00');
$timestamp_final = strtotime('2013-12-17 15:02:00');
$horas_transcurridas = date('H:i:s', $timestamp_final - $timestamp_initial);
echo $horas_transcurridas;