PHP计算页面执行时间

run_time.php  Code:

<?php
class runtime
{
var $StartTime = 0;
var $StopTime = 0;

function get_microtime()
{
list($usec, $sec) = explode(" ", microtime());
return ((float)$usec + (float)$sec);
}

function start()
{
$this->StartTime = $this->get_microtime();
}

function stop()
{
$this->StopTime = $this->get_microtime();
}

function spent()
{
return round(($this->StopTime - $this->StartTime) * 1000, 1);
}

}
?>

return_time_test.php  Code:

<?php
include ("run_time.php");

$runtime = new runtime;
$runtime->start();

$a = 0;
for ($i=0;$i&ltrim(1000000);$i++){
$a += $i;
}
$runtime->stop();
echo "页面执行时间：".$runtime->spent()."毫秒!";
?>