多态对象模型

一、多态
多态即多种形态，在c++中分为静态多态和动态多态，
静态多态：重载，编译期间决议确定。
动态多态：通过继承重写基类的虚函数实现的多态。
二、多态对象模型
单继承：

#include <iostream>using namespace std;class Base{public:    virtual void func1()    {        cout << "Base::fun1()" << endl;    }    virtual void func2()    {        cout << "Base::fun1()" << endl;    }public:    int a;};class Derive:public Base{public:    virtual void func1()    {        cout << "Derive::fun1()" << endl;    }    virtual void func3()    {        cout << "Derive::fun3()" << endl;    }    virtual void func4()    {        cout << "Derive::fun4()" << endl;    }public:    int b;};typedef void(*V_FUNC)();void PrintVTable(int* vtable){    printf("虚函数表:[%p]\n",vtable);    for (size_t i = 0; vtable[i]; ++i)    {        printf("vfunc[%d]:%p->", i, vtable[i]);        V_FUNC f = (V_FUNC)vtable[i];        f();    }    cout << "====================" << endl;}int main(){    Base b;    Derive d;    int* VTable = (int*)(*((int*)(&d)));    PrintVTable(VTable);    PrintVTable((int*)(*((int*)&b)));    b.func1();    b.func2();    d.func1();    d.func2();    d.func3();    d.func4();    system("pause");    return 0;}

多继承：

#include <iostream>using namespace std;class Base1{public:    virtual void f1()    {        cout << "Base1::f1()" << endl;    }    virtual void f2()    {        cout << "Base1::f2()" << endl;    }};class Base2{public:    virtual void f1()    {        cout << "Base2::f1()" << endl;    }    virtual void f2()    {        cout << "Base2::f2()" << endl;    }};class Derive :public Base1, public Base2{public:    virtual void f1()    {        cout << "Derive::f1()" << endl;    }    virtual void f3()    {        cout << "Derive::f3()" << endl;    }};typedef void(*V_FUNC)();void PrintVTable(int* vtable){    printf("虚函数表:[%p]\n", vtable);    for (size_t i = 0; vtable[i]; ++i)    {        printf("vfunc[%d]:%p->", i, vtable[i]);        V_FUNC f = (V_FUNC)vtable[i];        f();    }    cout << "====================" << endl;}int main(){Base1 b1;    Base2 b2;    Derive d;    int* VTable = (int*)(*((int*)(&b1)));    PrintVTable(VTable);    PrintVTable((int*)(*((int*)&b2)));    PrintVTable((int*)(*((int*)&d)));    system("pause");    return 0;}