108.虚函数表原理(获取虚函数)

//#include <iostream>
//using namespace std;
//
//
//void main()
//{
//    cin.get();
//}

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;

class father
{
public:
    //虚函数表存放在首地址
    virtual void go1()
    {
        cout << "go1" << endl;
    }
    virtual void go2()
    {
        cout << "go2" << endl;
    }
    virtual void go3()
    {
        cout << "go3" << endl;
    }
};

class son :public father
{
public:

    void go1()
    {
        cout << "son go1" << endl;
    }

    void go2()
    {
        cout << "son go2" << endl;
    }

    void go3()
    {
        cout << "son go3" << endl;
    }
};

void main()
{
    father *p = new son;
    cout << sizeof(*p) << endl;
    //对象的地址
    cout << (void*)p << endl;
    //虚函数表的地址
    cout << (void*)(*((int *)p)) << endl;
    //第一个元素的地址 类型转换->读内存->类型转换使得步长为4个字节
    cout << (void*)(   ((int *)*((int *)p) +0)      ) << endl;
    
    //取出函数表中的函数

    auto fun1 = (void*)(   *((int *)*((int *)p) + 0)   );
    auto fun2 = (void*)(   *((int *)*((int *)p) + 1)   );
    auto fun3 = (void*)(   *((int *)*((int *)p) + 2)   );

    typedef void(*P)();

    //函数指针数组
    P pfun[3];
    pfun[0] = (P)fun1;
    pfun[1] = (P)fun2;
    pfun[2] = (P)fun3;

    for (int i = 0; i < 3; i++)
    {
        pfun[i]();
    }
    cin.get();
}