一目了然c++虚基类！

 1 #include <IOSTREAM.H>  
 2 //基类  
 3 class CBase  
 4 ...{  
 5 protected:  
 6     int a;  
 7 public:  
 8     CBase(int na)  
 9     ...{  
10         a=na;  
11         cout<<"CBase constructor! ";  
12     }  
13   
14     ~CBase()...{cout<<"CBase deconstructor! ";}  
15 };  
16   
17 //派生类1(声明CBase为虚基类)  
18 class CDerive1:virtual public CBase  
19 ...{  
20 public:  
21     CDerive1(int na):CBase(na)  
22     ...{  
23         cout<<"CDerive1 constructor! ";  
24     }  
25       
26     ~CDerive1()...{cout<<"CDerive1 deconstructor! ";}  
27   
28     int GetA()...{return a;}  
29 };  
30   
31 //派生类2(声明CBase为虚基类)  
32 class CDerive2:virtual public CBase  
33 ...{  
34 public:  
35     CDerive2(int na):CBase(na)  
36     ...{  
37         cout<<"CDerive2 constructor! ";  
38     }  
39     ~CDerive2()...{cout<<"CDerive2 deconstructor! ";}  
40     int GetA()...{return a;}  
41 };  
42   
43 //子派生类  
44 class CDerive12:public CDerive1,public CDerive2  
45 ...{  
46 public:  
47     CDerive12(int na1,int na2,int na3):CDerive1(na1),CDerive2(na2),CBase(na3)  
48     ...{  
49         cout<<"CDerive12 constructor! ";  
50     }  
51     ~CDerive12()...{cout<<"CDerive12 deconstructor! ";}  
52 };  
53 void main()  
54 ...{  
55     CDerive12 obj(100,200,300);  
56     //得到从CDerive1继承的值  
57     cout<<" from CDerive1 : a = "<<obj.CDerive1::GetA();  
58     //得到从CDerive2继承的值  
59     cout<<" from CDerive2 : a = "<<obj.CDerive2::GetA()<<endl<<endl;  
60 }