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 $STime = 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 s(){//程序运行结束
$this->STime = microtime();
}
function spent(){//程序运行花费的时间
if ($this->TimeSpent) {
return $this->TimeSpent;
} else {
list($StartMicro, $StartSecond) = explode(" ", $this->StartTime);
list($SMicro, $SSecond) = explode(" ", $this->STime);
$start = doubleval($StartMicro) + $StartSecond;
$s = doubleval($SMicro) + $SSecond;
$this->TimeSpent = $s - $start;
return substr($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
$timer->s();
echo "程序运行时间为:".$timer->spent();