虚析构函数的作用

 1 #include<iostream>
 2 using namespace std;
 3 class P
 4 {
 5 public:
 6     P(){}
 7     virtual ~P(){cout<<"调用了基类的析构函数！"<<endl;}
 8     virtual void show()
 9     {
10         cout<<"调用了P类的输出函数"<<endl;
11     }
12 };
13 
14 class Q:public P
15 {
16 public:
17     Q(){}
18     ~Q(){cout<<"调用了派生类的析构函数！"<<endl;}
19         void show()
20     {
21         cout<<"调用了Q类的输出函数"<<endl;
22     }
23 };
24 void callshow(P *obj)
25 {
26     obj->show();
27 }
28 void main(void)
29 {
30     P *s=new Q;
31     callshow(s);
32     delete s;
33     system("pause");
34 }