c++类的函数重载、重写示例

1、文件cls.h
头文件cls.h实现了基类Base1、Base2，和子类Derived1、Derived2。

#pragma once#include <iostream>using namespace std;class Base1{public:    Base1() { cout << "Constrution Base1" << endl; }    //~Base1() { cout << "Destrution Base1" << endl; }    virtual ~Base1() { cout << "Destrution Base1" << endl; }    virtual void f() { cout << "Base1::f" << endl; }    virtual void g() { cout << "Base1::g" << endl; }    virtual void h() { cout << "Base1::h" << endl; }    void func(){ cout << "Base1::func" << endl; }};class Base2{public:    Base2() { cout << "Constrution Base2" << endl; }    //~Base2() { cout << "Destrution Base2" << endl; }    virtual ~Base2() { cout << "Destrution Base2" << endl; }    virtual void f() { cout << "Base2::f" << endl; }    virtual void g() { cout << "Base2::g" << endl; }    virtual void h() { cout << "Base2::h" << endl; }    void func() { }};class Derived1 :public Base1{public:    Derived1() { cout << "Constrution Derived1" << endl; }    ~Derived1() { cout << "Destrution Derived1" << endl; }    virtual void f() { cout << "Derived1::f" << endl; }   // virtual可写可不写    virtual void g1() { cout << "Derived1::g1" << endl; }    virtual void h1() { cout << "Derived1::h1" << endl; }    void func() { cout << "Derived1::func" << endl; }};class Derived2 :public Base2, public Base1{public:    Derived2() { cout << "Constrution Derived2" << endl; }    ~Derived2() { cout << "Destrution Derived2" << endl; }    virtual void f()  { cout << "Derived2::f" << endl;  }    virtual void g1() { cout << "Derived2::g1" << endl; }    virtual void h1() { cout << "Derived2::h1" << endl; }};

2、主函数
测试函数的派生、虚函数重写、重载等示例。

#include "cls.h"int main(){    Base1 b1;    Base2 b2;    Derived1 d1;    Derived2 d2;    // 大小与函数列表有关    cout << "sizeof(Base1) = " << sizeof(Base1) << " sizeof(b1) = " << sizeof(b1) << endl;    cout << "sizeof(Base2) = " << sizeof(Base2) << " sizeof(b2) = " << sizeof(b2) << endl;    cout << "sizeof(Derived1) = " << sizeof(Derived1) << " sizeof(d1) = " << sizeof(d1) << endl;    cout << "sizeof(Derived2) = " << sizeof(Derived2) << " sizeof(d1) = " << sizeof(d1) << endl;    Derived1 d;  // d 能直接调用Derived1的所有函数、Base1的非虚函数，间接调用base1的虚函数    d.f();        // Derived::f    d.g1();       // Derived::g1    d.Base1::f(); // Base1::f     d.func();    Derived1 *d = new Derived1(); // 同上    d->f();          // Derived::f    d->g1();         // Derived::g1    d->Base1::f();   // Base1::f    d->func();       // Derived1::func   重载    d->Base1::func();// Base1::func      间接调用，显示调用    Base1 *b = new Derived1(); // b 只能调用Base1的函数，但是虚函数会被动态绑定    b->f();     // Derived1::f     b->g();     // Base1::g    b->func();  // Base1::func    Base1 *b = new Base1(); // 显然只能调用base1的函数    b->f();   // Base1::f    b->g();   // Base1::g    b->func();// Base1::func    Base1 *b = new Base1();     delete b; // 不论基类析构函数是否为虚函数，都会执行函数体    Base1 *b = new Derived1();     delete b; // 当基类析构函数为虚时，才会析构父类;    否则，只执行基类的析构函数    Derived1 *d = new Derived1();    delete d;   // 不论基类析构函数是否为虚函数，都会执行函数体    Derived2 d2;//直接调用Derived2的函数，间接调用父类函数    d2.f();         // Derived2::f    d2.Base1::f();  // Base1::f    d2.Base2::f();  // Base2::f    Derived2 *d2 = new Derived2();//直接调用Derived2的函数，间接调用父类函数    d2->f();        // Derived2::f    d2->Base1::f(); // Base1::f    d2->Base2::f(); // Base2::f    delete d2;    Base1 *d2 = new Derived2();// 调用base1的函数和Derived2重写的函数，    d2->f();            // 子类重写 Derived2::f    d2->Base1::f();   // 间接调用父类虚函数 Base1::f        d2->g();            // 直接调用父类虚函数 Base1::g        d2->func();     // 直接调用父类非虚函数 Base1::func    delete d2;        //其中一个父类析构函数必须为虚函数    return 0;}