C++虚函数的实现机制示例

C++虚函数的实现机制是通过一个vtable表，指向子类的虚函数地址。

另外，如果不是虚函数，则不能实现用父类引用调用子类方法。

#include <windows.h>
#include <iostream>
using namespace std;

class CBase
{
public:
    void fun()
    {
        cout << "CBase::fun" << endl;
    }

    virtual void vfun1()
    {
        cout << "CBase::vfun1" << endl;
    }

    virtual void vfun2()
    {
        cout << "CBase::vfun2" << endl;
    }
};

class CDerive:public CBase
{
public:
    void fun()
    {
        cout << "CDerive::fun" << endl;
    }

    virtual void vfun1()
    {
        cout << "CDerive::vfun1" << endl;
    }
};

int main(int argc, TCHAR* argv[])
{
    cout << "hello world!" << endl;
    CDerive derive;
    CBase* pBase = (CBase*)(&derive);
    pBase->fun();
    pBase->vfun1();
    pBase->vfun2();

    cout << hex <<  *((int *)(*((int *)&derive))) << endl;
    cout << hex <<  *((int *)(*((int *)&derive)) + 1) << endl;
    
     cin.get();
    return 0;
}