프로그램 실행 시간을 계산하는 PHP 클래스

/**
* 计算程序运行时间
* filename: js_runtime.php
*/
class Timer {
private $StartTime = 0;//程序运行开始时间
private $StopTime = 0;//程序运行结束时间
private $TimeSpent = 0;//程序运行花费时间
function start(){//程序运行开始
$this->StartTime = microtime();
}
function stop(){//程序运行结束
$this->StopTime = microtime();
}
function spent(){//程序运行花费的时间
if ($this->TimeSpent) {
return $this->TimeSpent;
} else {
list($StartMicro, $StartSecond) = explode(" ", $this->StartTime);
list($StopMicro, $StopSecond) = explode(" ", $this->StopTime);
$start = doubleval($StartMicro)   $StartSecond;
$stop = doubleval($StopMicro)   $StopSecond;
$this->TimeSpent = $stop - $start;
return substr($this->TimeSpent,0,8)."秒";//返回获取到的程序运行时间差
}
}
}
$timer = new Timer();
$timer->start();
//...程序运行的代码
$timer->stop();
echo "程序运行时间为:".$timer->spent();
?>