The 13th Week "C + + language Basics" program reading-polymorphism and abstract class (3)

1, read the following program, and write the results of the operation
(3) Pure virtual function

#include <iostream>using namespace Std;class base{public:    virtual void who () = 0;}; Class Firstderived:public Base{public:    void Who () {cout<< "F";}}; Class Secondderived:public Base{public:    void Who () {cout<< "S";}}; int main () {    firstderived first_obj;    Secondderived second_obj;    Base &bref=first_obj;    Bref. Who ();    Bref=second_obj;    Bref. Who ();    Base *bp;    bp=&first_obj;    Bp->who ();    bp=&second_obj;    Bp->who ();    return 0;}

Expected operating Result: FSFS

Actual running results:

Error Analysis: Base &bref=first_obj; This sentence means bref for first_obj, and bref=second_obj; Second_obj for First_. obj assignment But there is no data member so there is no confusion. So the output fffs.

The 13th Week "C + + language Basics" program reading-polymorphism and abstract class (3)