php中计算程序运行时间的类代码

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();