Datetime difference in Hour

datetime_diff.php

<?php
function getTimeDifference($start_time,$stop_time){  $start_time=strtotime($start_time);  $stop_time=strtotime($stop_time);  $seconds=$stop_time - $start_time;  if($seconds > 3600 ){   $hours=floor($seconds / 3600);   $seconds=$seconds % 3600;  }else{   $hours='00';  }  if($seconds > 60 ){   $minutes=floor($seconds / 60);   $seconds=$seconds % 60;  }else{   $minutes='00';  }  return $hours.':'.$minutes.':'.$seconds; }  echo getTimeDifference('2013-05-11 13:24:48','2013-05-12 13:59:49');