#include <iostream>
  
class Mammal
{
public:
    Mammal():age(1) {  }
    ~Mammal() { }
    virtual void speak() const { std::cout << "Mammal speak!\n"; }
protected:
    int age;
};
  
class Dog : public Mammal
{
public:
    void speak() const { std::cout << "Woof!\n"; }
};
  
class Cat : public Mammal
{
public:
    void speak()const { std::cout << "Meow!\n"; }
};
  
void valueFunction(Mammal);
void ptrFunction(Mammal*);
void refFunction(Mammal&);
  
int main()
{
    Mammal* ptr=0;
    int choice;
    while (1)
    {
        bool fQuit = false;
        std::cout << "(1) dog (2) cat (0) quit: ";
        std::cin >> choice;
        switch (choice)
        {
        case 0: 
            fQuit = true;
            break;
        case 1: 
            ptr = new Dog;
            break;
        case 2: 
            ptr = new Cat;
            break;
        default: 
            ptr = new Mammal;
            break;
        }
        if (fQuit)
        {
            break;
        }
        ptrFunction(ptr);
        refFunction(*ptr);
        valueFunction(*ptr); 
    }
    return 0;
}
  
void valueFunction(Mammal mammalValue)  // This function is called last
{
    mammalValue.speak();
}
  
void ptrFunction (Mammal *pMammal)
{
    pMammal->speak();
}
  
void refFunction (Mammal &rMammal)
{
    rMammal.speak();
}