Play的构造方法中这句代码:

$this->height = $height;

相当于给player增加了一个height属性...

class Human{

    private   $height;

    public function setHeight($h){

    $this->height=$h;

    }

    public function printHeight(){

    echo "Human height:".$this->height;

    }

}

class Player extends Human {

    protected $age;

    function __construct($name,$height){ 

         $this->name = $name;

         $this->height = $height;

         }

}

$joden=new Player('joden','25');

echo 'Player Heihgt:'.$joden->height;

echo '<br>';

echo '调用 Human 方法设置Human 的私有height:<br>';

echo $joden->setHeight(30);

echo $joden->printHeight();

echo '<br>';

echo '再次打印Player的Heihgt:'.$joden->height;