while和do while

先判断下能不能打得过，再确定打不打

    public function test1(){
        set_time_limit(0);
        $x =1;
        while($x<=500){
            print str_repeat(' ', 50000);
            echo "数字是：$x <br>";
            ob_flush();
            flush();
            sleep(1);
            $x++;
        }
        echo '结束';
        ob_end_flush();
    }

先打一拳，再确定打不打的过

    public function test2(){
    
        $x =6;
        do {
            print str_repeat(' ', 50000);
            echo "数字是：$x <br>";
            ob_flush();
            flush();
            sleep(1);
        } while ($x <= 5);
        echo '结束';
        ob_end_flush();
    }