求解

#include<iostream>

using namespace std;

class base
{public:
        void who(){cout<<"base class"<<endl;}
};

class derive1:public base
{public:
        void who(){cout<<"derive1 class"<<endl;}
};

class derive2:public base
{public:
        void who(){cout<<"derive2 class"<<endl;}
};     

      
int main()
{
    base obj1,*p;
    derive1 obj2;
    derive2 obj3;
    p=&obj1;
    p->who();
    p=&obj2;
    p->who();
    p=&obj3;
    p->who();
    obj2.who();
    obj3.who();


return 0;
}