PHP calculates current program execution time

$pagestartime=microtime();
?>

Web page content
...
...

$pageendtime = microtime();
$starttime = explode(" ",$pagestartime);
$endtime = explode(" ",$pageendtime);
$totaltime = $endtime [0]-$starttime[0]+$endtime[1]-$starttime[1];
$timecost = sprintf("%s",$totaltime);
echo "Page running time: $timecost seconds";
 ?>

Source: PHP Chinese website