【C++】 --- 虚析构函数

1. #define _CRT_SECURE_NO_WARNINGS
2. #include <iostream>
3. using namespace std;
4. 
5. class A
6. {
7. public:
8.  A()
9.  {
10.     p = new char[20];
11.     strcpy(p, "obja");
12.     cout << "A" << endl;
13.   }
14.    virtual ~A()
15.   {
16.     delete[] p;
17.     cout << "~A" << endl;
18.   }
19. 
20. private:
21.   char *p;
22. };
23. 
24. class B :public A
25. {
26. public:
27.   B()
28.   {
29.     p = new char[20];
30.     strcpy(p, "objb");
31.     cout << "B" << endl;
32.   }
33.   ~B()
34.   {
35.     delete[] p;
36.     cout << "~B" << endl;
37.   }
38. protected:
39. 
40. private:
41.   char *p;
42. };
43. 
44. class C :public B
45. {
46. public:
47.   C()
48.   {
49.     p = new char[20];
50.     strcpy(p, "objc");
51.     cout << "C" << endl;
52.   }
53.   ~C()
54.   {
55.     delete[] p;
56.     cout << "~C" << endl;
57.   }
58. protected:
59. 
60. private:
61.   char *p;
62. };
63. 
64. void howtoDelete(A *base)
65. {
66.   delete base;    //不会变现出多态的属性
67. }
68. 
69. int main()
70. {
71.   A *p = new C();
72.   delete p;
73. 
74.   C *p1 = new C();
75.   howtoDelete(p1);
76. 
77. 
78.   system("pause");
79. }
80.