1 #include <iostream>
2
3 class A
4 {
5 public:
6 A(){}
7 ~A(){}
8 virtual int data(){return 1;}
9 };
10 class B:public A
11 {
12 public:
13 B(){}
14 ~B(){}
15 int data(){return 2;}
16 };
17
18 class C:public A
19 {
20 public:
21 C(){}
22 ~C(){}
23 int data(){return 3;}
24 };
25
26 class D:public C
27 {
28 public:
29 D(){}
30 ~D(){}
31 int data(){return 4;}
32 };
33
34 int main()
35 {
36
37 std::cout<<"dynamic_cast begin \n";
38 A *a=new A;
39 B *b=new B;
40 C *c=new C;
41 D *d=new D;
42
43 if(dynamic_cast<B*> (a)) //this will fail 派生类不能指向基类
44 {
45 std::cout<<"A *a convert B class ok\n";
46 }
47
48 if(dynamic_cast<A*> (b)) // this will be ok 基类指向派生类 ok
49 {
50 std::cout<<"B *b convert A class ok\n";
51 }
52
53
54 if(dynamic_cast<C*> (a)) // 派生类不能指向基类
55 {
56 std::cout<<"A *a convert C class ok\n";
57 }
58
59 if(dynamic_cast<A*> (c)) //c派生类 所以可以被A指向
60 {
61 std::cout<<"A *a convert C class ok\n";
62 }
63
64 if(dynamic_cast<A*> (d)) // A <- C <- D 基类可以指向派生类 ok
65 {
66 std::cout<<"D *d convert A class ok\n";
67 }
68
69 if(dynamic_cast<D*> (c)) // 派生类不能指向基类
70 {
71 std::cout<<"C *c convert D class ok\n";
72 }
73
74 if(dynamic_cast<C*> (d)) // C基类可以指向派生类D ok
75 {
76 std::cout<<"D *d convert C class ok\n";
77 }
78
79 if(dynamic_cast<D*> (d)) // ok
80 {
81 std::cout<<"d *d convert D class ok\n";
82 }
83
84 std::cin.get();
85 return 0;
86 }
