C++析構函數需要加virtual

 1 #include<iostream>  
 2 using namespace std;  
 3 
 4 class Base  
 5 {  
 6 public:  
 7     Base() 
 8     {
 9         cout << "base" << endl;
10     } //Base的構造函數  
11     virtual ~Base() //Base的析構函數  
12     {  
13         cout << "~Base!" << endl;  
14     } 
15 };  
16 
17 class Derived : public Base  
18 {  
19 public:  
20     Derived() 
21     {
22         cout << "drived" << endl;
23     } //Derived的構造函數  
24     ~Derived() //Derived的析構函數  
25     {  
26         cout << "~Derived!" << endl;  
27     }   
28 };  
29 /*基類要用virtual的原因*/
30 int main()  
31 {  
32     Derived *pTest1 = new Derived(); //Derived類的指針  
33     delete pTest1;  
34 
35     cout << endl;  
36 
37     Base *pTest2 = new Derived(); //Base類的指針  
38     delete pTest2;  
39 
40     return 0;  
41 }