Question

class Player
{

protected:

  string type;
  int rank;

public:

  virtual void printType()
  {
      cout<<"Calling Class Player, type is: general Player"<<endl;
  }

};


//class FootballPlayer: Derived from Player

class FootballPlayer: public  Player 
{

protected:

public:

  virtual void printRank()
  {
    cout<<"Calling Class FootballPlayer, Rank is: Football Player rank"<<endl;

  }  

  void printType()
  {
    cout<<"Calling Class FootballPlayer, type is: Football Player"<<endl;
  }
};

class MaleFootballPlayer: public FootballPlayer  
{
public:

  void printType()
  {
    cout<<"Calling Class MaleFootballPlayer, type is: Male Football Player"<<endl;
  }


  void printRank()
  {
    cout<<"Calling Class MaleFootballPlayer, Rank is: Male Player rank"<<endl;

  }

};

//class CricketPlayer: Derived from Player

class CricketPlayer: public Player
{

protected:

public:

  void printType()
  {
    cout<<"Calling Class CricketPlayer, type is: Cricket Player"<<endl;
  }
};


int  main(int argc, const char * argv[])
{

  FootballPlayer fbplayer;
  CricketPlayer crplayer;
  MaleFootballPlayer malefbplayer;


  FootballPlayer *fbplayerPtr;
  fbplayerPtr=&malefbplayer;
  fbplayerPtr->printType();


  return 0; 
}

当我运行程序时，我得到的输出是，

调用类MaleFootballPlayer，输入是：男子足球运动员

我正在创建一个基类指针（footballplayer）并分配给派生类对象（malefootballplayer），它应该调用属于基类的函数（因为它不是虚拟的），输出应该是'调用类FootBallPlayer ，类型是：足球运动员'。

希望清除我的概念。

感谢。

Answer 1

由于MaleFootballPlayer对象的地址包含在FootballPlayer类型指针中，而printType（）方法在基本实现中声明为virtual，因此派生类MaleFootballPlayer函数会覆盖它。这就是为什么会这样。虚拟表包含两个类的两个printType（）函数的指针，但运行时选择了派生类printType（）函数指针。

多级继承与多态

1 个答案: