C++ 虚函数

 1 using namespace std;
 2 #include <iostream>
 3 
 4 using namespace std;
 5 
 6 class A{                                                                                                                                                                                        
 7 public:
 8     virtual void Fun1(){
 9         cout << "A::Func1" << endl;
10     }   
11 
12     virtual void Fun2(){
13         cout << "A::Func2" << endl;
14     }   
15 };
16 
17 class B : public A{
18 public:
19     virtual void Fun1(){
20         cout << "B::Func1" << endl;
21     }   
22 
23     virtual void Fun3(){
24         cout << "B::Func3" << endl;
25     }   
26 };
27 
28 class C : public B{
29 public:
30     virtual void Fun1(){
31         cout << "C::Func1" << endl;
32     }   
33 
34     virtual void Fun4(){
35         cout << "C::Func4" << endl;
36     }   
37 };
38 
39 typedef void(*FUNC)();
40 int main()
41 {
42     A a;
43     cout << "A::虚表" << endl << endl;
44     ((FUNC)(*(long*)(*(long*)(&a))))();
45     ((FUNC)(*((long*)(*(long*)(&a)) + 1)))();
46     cout << "------------------------" << endl;
47 
48     B b;
49     cout << "B::虚表" << endl << endl;
50     ((FUNC)(*(long*)(*(long*)(&b))))();
51     ((FUNC)(*((long*)(*(long*)(&b)) + 1)))();
52     ((FUNC)(*((long*)(*(long*)(&b)) + 2)))();
53     cout << "------------------------" << endl;
54 
55     C c;
56     cout << "C::虚表" << endl << endl;
57     ((FUNC)(*(long*)(*(long*)(&c))))();
58     ((FUNC)(*((long*)(*(long*)(&c)) + 1)))();
59     ((FUNC)(*((long*)(*(long*)(&c)) + 2)))();
60     ((FUNC)(*((long*)(*(long*)(&c)) + 3)))();
61     cout << "------------------------" << endl;
62     return 0;
63 }
虚函数
虚函数表继承替换原则：
有则替换，无则末尾追加。