<?php   //定义父类   class Stu{    public $name;    protected $age;    protected $grade;    private $address;//私有变量不会被继承        //当一个子类的方法和父类的方法完全一样，称为方法的重写    public function __construct(){      echo "Stu 构造函数";    }    public function showInfo()    {       echo $this->name."||".$this->age;    }   }   Class Pupil extends Stu{ //集成父类用extends关键字，类是单继承的不能多继承    public function tesing()    {       echo "小学生考试。。。。。";    }   }   Class Graduate extends Stu{      public function tesing(){        echo "大学生考试。。。。。";      }   }   //调用父类的成员方式   //1.类名::方法名();   //2.parent::方法名();      $stu1=new Pupil();   $stu1->name="小明";   $stu1->tesing();   $stu1->showInfo();      $stu2=new Graduate();   $stu2->name="大明";   $stu2->tesing();   $stu2->showInfo();?>