Use Virtual Functions to change the method behaviour : virtual function « Class « C++ Tutorial

1. C++ Tutorial
2. Class
3. virtual function

#include <iostream>  
using namespace std;
class Base {  
public:  
  virtual void who(void) {
    cout << "Base\n";  
  }  
};  
     
class first_d : public Base {  
public:  
  void who(void) { // define who() relative to first_d  
    cout << "First derivation\n";  
  }  
};  
     
class second_d : public Base {  
public:  
  void who(void) { // define who() relative to second_d  
    cout << "Second derivation\n";  
  }  
};  
     
int main(void)  
{  
  Base base_obj;  
  Base *p;  
  first_d first_obj;  
  second_d second_obj;  
     
  p = &base_obj;  
  p->who();  // access Base's who  
     
  p = &first_obj;  
  p->who(); // access first_d's who  
     
  p = &second_obj;  
  p->who();  // access second_d's who  
     
  return 0;  
}