virtual 析构函数作用

析构函数不使用virtual的情况：

class base{public:base(){cout<<"construct base"<<endl;}~base(){cout<<"destroy base"<<endl;}};class derived:public base{public:derived(){cout<<"construct derived"<<endl;}~derived(){cout<<"destroy derived"<<endl;}};int main(){derived* d = new derived;delete d;cout<<endl;base* b = new derived;delete b;return 1;}

输出：

析构函数使用virtual的情况：

class base{public:base(){cout<<"construct base"<<endl;}virtual ~base(){cout<<"destroy base"<<endl;}};class derived:public base{public:derived(){cout<<"construct derived"<<endl;}~derived(){cout<<"destroy derived"<<endl;}};int main(){derived* d = new derived;delete d;cout<<endl;base* b = new derived;delete b;return 1;}

输出：

总结：

在多态中，不使用virtual时，子类在释放时不会调用父类的析构函数，会造成内存泄露。