类访问的动态绑定

/*

**test28.cpp : Defines the entry point for the console application.

**系统winXP SP3 32位.

**类访问的动态绑定

*/

#include "stdafx.h"

#include "iostream.h"

class A{

public:

virtual void f(){

cout<<"A::fA1()"<

};

};

class B:public A{

public:

void f(){

cout<<"B::fB1()"<

};

};

class C:public B{

public:

void f(){

cout<<"C::fC1()"<

};

};

class D{

public:

virtual ~ D(){}

virtual void output(){};

};

class E:public D{

public:

E():eNum(0){}

virtual ~E(){}

virtual void output(int){

cout<<"E::fE1(int)"<

}

virtual void output(){

cout<<"E::fE1()"<

}

private:

int eNum;

};

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

{

A* pa = NULL;

A a;

B b;

C c;

a.f(); //fA1()

b.f(); //fB1()

c.f(); //fC1()

pa = &a;

pa->f(); //fA1()

pa = &b;

pa->f(); //fB1(),程序会根据动态绑定来确定具体调用的函数，若上面的父类A中函数不为virtual型，则此处调用的是fA1()

int iNum = 0;

D d;

D* pd= &d;

//pd->output(iNum); //错误

pd->output(); //空白输出

E* pe = new E;

pe->output(); //E::fE1()

pe->output(iNum); //E::fE1(int)

return 0;

}

Tips1：派生类的函数或成员变量会遮蔽掉父类中的同名函数或成员变量。