php测试程序运行速度和页面执行速度的代码

 <?php
class timer {    
var $StartTime = 0;    
var $StopTime = 0;    
var $TimeSpent = 0;    
function start(){    
$this->StartTime = microtime();    
}    
 
function stop(){    
$this->StopTime = microtime();    
}    
 
function spent() {    
if ($this->TimeSpent) {    
return $this->TimeSpent;    
} else {    
$StartMicro = substr($this->StartTime,0,10);    
$StartSecond = substr($this->StartTime,11,10);    
$StopMicro = substr($this->StopTime,0,10);    
$StopSecond = substr($this->StopTime,11,10);    
$start = floatval($StartMicro) + $StartSecond;    
$stop = floatval($StopMicro) + $StopSecond;    
$this->TimeSpent = $stop - $start;    
return round($this->TimeSpent,8).'秒';    
}  
} // end function spent();    
 
} //end class timer;  
 
//$timer = new timer;//实例化测试类  
//$timer->start();//放在代码开始执行的测试点

//$timer->stop();   //放在代码执行结束的测试点
//print_r('</br>运行时间为: '.$timer->spent()) ;
//unset($timer);