虚析构函数

#include <iostream>

using namespace std;

class A
{
public:
    A()
    {
        cout << "A create" << endl;
    }
    virtual ~A()
    {
        cout << "A delete" << endl;
    }
};


class B:public A
{
public:
    B()
    {
        cout << "B create" << endl;
    }
    ~B()
    {
        cout << "B delete" << endl;
    }
};

int main()
{
   A *p = new B;  
//因为这里的p是基类的指针.但指向子类的对象.所以.
//对p操作首先就是操作子类的相关成员,因此delete p首先就是调用子类的析构函数.一旦调用子类的析构函数.也是首先调用父类的析构函数.由此避免内存泄漏
   delete p;
    cin.get();
    return 0;
}