5.9

 1 #include<iostream>
 2 using namespace std;
 3 class BaseClass
 4 {
 5 public:
 6     virtual void fn1();
 7     void fn2 ();
 8 };
 9 void BaseClass::fn1()
10 {
11     //cout<<"调用基类的虚函数fn1()"<<endl;
12 }
13 void BaseClass::fn2()
14 {
15     cout<<"调用基类的虚函数fn2()"<<endl;
16 }
17 class DerivedClass:public BaseClass
18 {
19 public:
20     void fn1();
21     void fn2();
22 };
23 void DerivedClass::fn1()
24 {
25     cout<<"调用派生类的函数fn1()"<<endl;
26 }
27 void DerivedClass::fn2()
28 {
29     cout<<"调用派生类的函数fn2()"<<endl;
30 }
31 int main()
32 {
33     DerivedClass aDerivedClass;
34     DerivedClass*pDerivedClass=&aDerivedClass;
35     BaseClass*pBaseClass=&aDerivedClass;
36     pBaseClass->fn1();
37     pBaseClass->fn2();
38     pDerivedClass->fn1();
39     pDerivedClass->fn2();
40 }