PHP test program running time class_PHP tutorial

class runTime {
private $starTime;//Start time
private $ stopTime;//End time
private function getMicTime(){
$mictime=microtime();//Get timestamp and microseconds
list($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 End time
$this->stopTime=$this->getMicTime();
}
public function spent(){//Calculate 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();
?>