#include <iostream>
using namespace std;
class Base
{
public:
    Base()
    {
        cout <<"constructor base\n";
    }
    virtual ~Base()
    {
        cout <<"Destructor base \n";
    }

};

class Derived:public  Base
    {
public:
    Derived()
    {
        cout <<"constructor Derived\n";

    }
   ~Derived() override
    {
        cout <<"Destructor Derived\n";
    }


};

int main()
{

Base * base  = new Base();
delete base;
cout <<"---------------"<<endl;
Derived *derived  = new Derived();
delete derived;
cout <<"---------------"<<endl;
Base* poly =  new Derived();
//注意当析构函数前面不加virtual keyword，析构时的第三种情况
delete poly;
return 0;
/**
 * output: base class 析构函数不加virtual
constructor base
Destructor base
---------------
constructor base
constructor Derived
Destructor Derived
Destructor base
---------------
constructor base
constructor Derived
Destructor base
 *
 */



}