C++ Class Inheritance calls to the base class and derived class who() functions

 
#include <string>
#include <iostream>
using std::string;
 
class Animal/* w w w  . ja va 2 s  .  c om*/
{
private:
  string name;                         // Name of the animal
  int weight;                          // Weight of the animal
public:
  Animal(string aName, int wt);        // Constructor
  void who() const;                    // Display name and weight
};
 
class Lion: public Animal
{
public:
  Lion(string aName, int wt) : Animal(aName, wt) {}
  void who() const;                    // Public member to access protected base function
};
 
class Fish: public Animal
{
public:
  Fish(string aName, int wt) : Animal(aName, wt){}
  void who() const;                    // Public member to access protected base function
};
using std::string;
 
// Constructor
Animal::Animal(string aName, int wt): name(aName), weight(wt) {}
 
// Identify the animal
void Animal::who() const {
  std::cout << "My name is " << name << " and I weigh " << weight << "lbs." << std::endl;
}
 
// Identify the Lion
void Lion::who() const {
  std::cout << "I am a lion.\n";
  Animal::who();                       // Call base function
}
 
// Identify the Fish
void Fish::who() const {
  std::cout << "\nI am an aardvark.\n";
  Animal::who();                       // Call base function
}
 
int main()
{
  Lion myLion("Leo", 400);
  Fish myFish("Algernon", 50);
  std::cout << "Calling derived versions of who():\n";
  myLion.who();
  myFish.who();
 
  std::cout << "\nCalling base versions of who():\n";
  myLion.Animal::who();
  myFish.Animal::who();
}