020--C++养成之路（多态：虚析构）

笔记：虚析构函数（virtual）

没使用virtual:

#include<iostream> #include<string> using namespace std; //虚析构 class A{ public: A(){ cout<<"A构造"<<endl; } ~A(){ cout<<"A析构"<<endl; } }; class B:public A{ int* p; public: B(){ p=new int(10); cout<<"B构造"<<endl; } ~B(){ if(p){ delete p; } cout<<"B析构"<<endl; } }; int main(){ A* a=new B(); delete a; getchar(); return 0; }

结果：

使用了virtual:

#include<iostream> #include<string> using namespace std; //虚析构 class A{ public: A(){ cout<<"A构造"<<endl; } virtual ~A(){ cout<<"A析构"<<endl; } }; class B:public A{ int* p; public: B(){ p=new int(10); cout<<"B构造"<<endl; } ~B(){ if(p){ delete p; } cout<<"B析构"<<endl; } }; int main(){ A* a=new B(); delete a; getchar(); return 0; }

结果：