浅析C++中的重载,隐藏和覆盖

class Base
{
public:
	Base(int data=10):ma(data){
	   cout<<"Base"<<endl;
        }
	void show(){cout<<"Base Show()"<<endl;}
	void show(int){cout<<"Base Show(int)"<<endl;}
	~Base(){cout<<"~Base()"<<endl;}
protected:
	int ma;
};

class Derive : public Base
{
	public:
	Derive(int data=20):Base(data),mb(data){
	      cout<<"Derive"<<endl;
	}
        ~Derive(){cout<<"~Derive()"<<endl;}
	private:
        int mb;
};

int main(){

     Derive d(20); 
     d.show(); //正常调用基类show()
     d.show(100); //正常调用基类show(int)
     return 0;

}

class Base
{
public:
        Base(int data=10):ma(data){
	   cout<<"Base"<<endl;
        }
	void show(){cout<<"Base Show()"<<endl;}
	void show(int){cout<<"Base Show(int)"<<endl;}
	~Base(){cout<<"~Base()"<<endl;}
protected:
	int ma;
};

class Derive : public Base
{
	public:
	   Derive(int data=20):Base(data),mb(data){
	      cout<<"Derive"<<endl;
	   }
	void show(){cout<<"Derive Show()"<<endl;}
        ~Derive(){cout<<"~Derive()"<<endl;}
	private:
        int mb;
};

int main(){

     Derive d(20);
     d.show();   //调用子类show()
     d.show(100);//调用报错 报错信息 "Derive::show()函数不接受1个参数"
     // 即 Derive中的show()方法把Base中的show()和show(int)都给隐藏掉了
     // 所以d.show()没问题,调用的是派生类的show(),但是d.show(100)报错了,因为
     // 父类的show()和show(int)都被隐藏了,而派生类Derive中没有 show(int)方法所以报错了
     // 如果想调用父类的show(int) 要这样写 d.Base.show(100);
     return 0;

}

class Base
{
public:
        Base(int data=10):ma(data){
	   cout<<"Base"<<endl;
        }
	void show(){cout<<"Base Show()"<<endl;}
	void show(int){cout<<"Base Show(int)"<<endl;}
	~Base(){cout<<"~Base()"<<endl;}
protected:
	int ma;
};

class Derive : public Base
{
     public:
	Derive(int data=20):Base(data),mb(data){
	      cout<<"Derive"<<endl;
	}
	void show(){cout<<"Derive Show()"<<endl;}
        ~Derive(){cout<<"~Derive()"<<endl;}
	private:
        int mb;
};

int main(){
Base   b(10);
Derive d(20);
Base  *pb =&d;
pb->show();    //调用的是基类的 show 
pb->show(100);//调用的是基类的 show(int)

（(Derive *）pb)->show();    //强转后 调用的是派生类的 show 


}

#include <iOStream>
using namespace  std;

class Base{

public:
  Base(){
     cout<<"Base()"<<endl;
  }
  void show(){
     cout<<"Base show()"<<endl;
  }
  void show(int x){
     cout<<"Base show(int x)"<<endl;
  }
  ~Base(){
     cout<<"~Base()"<<endl;
  }

private:
     int ma;

};


class Derive :public Base{

public:
  Derive(){
     cout<<"Derive()"<<endl;
  }

  void show(){
     cout<<"Derive show()"<<endl;
  }

  ~Derive(){
     cout<<"~Derive()"<<endl;
  }

private:
     int ma;

};

int main(){

    Derive d;
    Derive *pd=&d;
    d.show();
    d.show(100);  //编译报错, Derive 的void show()方法把Base 的void show() void show(int x) 都隐藏了
    pd->show(100);//编译报错  Derive 的void show()方法把Base 的void show() void show(int x) 都隐藏了
    return 0;
}

#include <iostream>

using namespace  std;

class Base{

public:
  Base(){
     cout<<"Base()"<<endl;
  }

  virtual void show(){
     cout<<"Base show()"<<endl;
  }
  void show(int x){
     cout<<"Base show(int x)"<<endl;
  }
  ~Base(){
     cout<<"~Base()"<<endl;
  }

private:
     int ma;

};



class Derive :public Base{

public:
  Derive(){
     cout<<"Derive()"<<endl;
  }

  virtual void show(){
     cout<<"Derive show()"<<endl;
  }

  ~Derive(){
     cout<<"~Derive()"<<endl;
  }

private:
     int ma;

};



int main(){

    Derive *pd=new Derive();
    pd->show(100); //编译报错,Derive 中的show() 函数,只要名字与Base中有相同名字的函数的,就会隐藏掉Base中所有的show方法(不管加不加virtual),包括void show() void show(int x)

    return 0;

}