A class for testing the running time of php programs

class runTime {
private $starTime;//Start time
private $stopTime;//End time
private function getMicTime(){
$mictime=microtime();//Get time Stamp and microseconds
list($usec,$sec)=explode(" ",$mictime);//Split the microseconds into arrays and convert them into variables for processing
return (float)$usec+(float)$sec ;//Force the converted data to be processed with floating point points
}
public function star(){//Get the start time
$this->starTime=$this->getMicTime();
}
public function stop(){//Get the end time
$this->stopTime=$this->getMicTime();
}
public function spent(){//Calculate the program duration
return round($this-> stopTime-$this->starTime)*1000;//Get the number of milliseconds
}
}
//Example
$time=new runTime();
$time->star();
for ($i= 1;$i<=1000;$i++){
echo("a");
}
$time->stop();
echo $time->spent();
?>