析构函数和虚析构函数

 1 #include <iostream>
 2
 3
 4 using namespace std;
 5
 6 class A
 7 {
 8 public:
 9     A() { cout << "构造A!" << endl; };
10     virtual ~A() { cout << "析构A!" << endl; };
11
12     virtual void DoSomething() { cout << "A的DoSomething!" << endl; };
13 };
14
15 class B : public A
16 {
17 public:
18     B() { cout << "构造B!" << endl; };
19     ~B() { cout << "析构B!" << endl; };
20
21     void DoSomething() { cout << "B的DoSomething!" << endl; };
22 };
23
24 int main()
25 {
26     A *Test1 = new A;
27     cout << "**************" << endl;
28     Test1->DoSomething();
29     cout << "**************" << endl;
30     delete Test1;
31     cout << "**************" << endl;
32     B *Test2 = new B;
33     cout << "**************" << endl;
34     Test2->DoSomething();
35     cout << "**************" << endl;
36     delete Test2;
37     cout << "**************" << endl;
38     A *Test3 = new B;
39     cout << "**************" << endl;
40     Test3->DoSomething();
41     cout << "**************" << endl;
42     delete Test3;
43     return 0;
44 }

运行结果：

修改代码，删除virtual

 1 #include <iostream>
 2
 3
 4 using namespace std;
 5
 6 class A
 7 {
 8 public:
 9     A() { cout << "构造A!" << endl; };
10      ~A() { cout << "析构A!" << endl; };
11
12     virtual void DoSomething() { cout << "A的DoSomething!" << endl; };
13 };
14
15 class B : public A
16 {
17 public:
18     B() { cout << "构造B!" << endl; };
19     ~B() { cout << "析构B!" << endl; };
20
21     void DoSomething() { cout << "B的DoSomething!" << endl; };
22 };
23
24 int main()
25 {
26     A *Test1 = new A;
27     cout << "**************" << endl;
28     Test1->DoSomething();
29     cout << "**************" << endl;
30     delete Test1;
31     cout << "**************" << endl;
32     B *Test2 = new B;
33     cout << "**************" << endl;
34     Test2->DoSomething();
35     cout << "**************" << endl;
36     delete Test2;
37     cout << "**************" << endl;
38     A *Test3 = new B;
39     cout << "**************" << endl;
40     Test3->DoSomething();
41     cout << "**************" << endl;
42     delete Test3;
43     return 0;
44 }

运行结果：

如果是是

B b;

结果：