4.21
1 #include<iostream> 2 using namespace std; 3 class BaseClass 4 { 5 public: 6 BaseClass() 7 { 8 cout<<"构造基类对象"<<endl; 9 } 10 }; 11 class DerivedClass:public BaseClass 12 { 13 public: 14 DerivedClass() 15 { 16 cout<<"构造派生类对象"<<endl; 17 } 18 }; 19 int main() 20 { 21 DerivedClass d; 22 }
1 #include<iostream> 2 using namespace std; 3 class BaseClass 4 { 5 public: 6 int fn1() 7 { 8 cout<<"调用基类的函数fn1()"<<endl; 9 } 10 int fn2() 11 { 12 cout<<"调用基类的函数fn2()"<<endl; 13 } 14 }; 15 class DerivedClass:public BaseClass 16 { 17 public: 18 int fn1() 19 { 20 cout<<"调用派生类的函数fn()1"<<endl; 21 } 22 int fn2() 23 { 24 cout<<"调用派生类的函数fn()2"<<endl; 25 } 26 }; 27 int main() 28 { 29 DerivedClass a; 30 DerivedClass *p1=&a; 31 BaseClass *p2=&a; 32 a.fn1(); 33 a.fn2(); 34 p1->fn1(); 35 p1->fn2(); 36 p2->fn1(); 37 p2->fn2(); 38 }