list1204.cpp

teach yourself C++ in 21 days 第五版

//Listing 12.4 Overloading constructors in derived classes
#include <iostream>
using namespace std;

enum BREED { GOLDEN, CAIRN, DANDIE, SHETLAND, DOBERMAN, LAB };

class Mammal
{
  public:
    // constructors
    Mammal();
    Mammal(int age);
    ~Mammal();

    //accessors
    int GetAge() const { return itsAge; }
    void SetAge(int age) { itsAge = age; }
    int GetWeight() const { return itsWeight; }
    void SetWeight(int weight) { itsWeight = weight; }

    //Other methods
    void Speak() const { cout << "Mammal sound!\n"; }
    void Sleep() const { cout << "shhh. I'm sleeping.\n"; }


  protected:
    int itsAge;
    int itsWeight;
};

class Dog : public Mammal
{
  public:

    // Constructors
    Dog();
    Dog(int age);
    Dog(int age, int weight);
    Dog(int age, BREED breed);
    Dog(int age, int weight, BREED breed);
    ~Dog();

    // Accessors
    BREED GetBreed() const { return itsBreed; }
    void SetBreed(BREED breed) { itsBreed = breed; }

    // Other methods
    void WagTail() const { cout << "Tail wagging...\n"; }
    void BegForFood() const { cout << "Begging for food...\n"; }

  private:
    BREED itsBreed;
};

Mammal::Mammal():
itsAge(1),
itsWeight(5)
{
   cout << "Mammal constructor..." << endl;
}

Mammal::Mammal(int age):
itsAge(age),
itsWeight(5)
{
   cout << "Mammal(int) constructor..." << endl;
}

Mammal::~Mammal()
{
   cout << "Mammal destructor..." << endl;
}

Dog::Dog():
Mammal(),
itsBreed(GOLDEN)
{
   cout << "Dog constructor..." << endl;
}

Dog::Dog(int age):
Mammal(age),
itsBreed(GOLDEN)
{
   cout << "Dog(int) constructor..." << endl;
}

Dog::Dog(int age, int weight):
Mammal(age),
itsBreed(GOLDEN)
{
   itsWeight = weight;
   cout << "Dog(int, int) constructor..." << endl;
}

Dog::Dog(int age, int weight, BREED breed):
Mammal(age),
itsBreed(breed)
{
    itsWeight = weight;
    cout << "Dog(int, int, BREED) constructor..." << endl;
}
 
Dog::Dog(int age, BREED breed):
Mammal(age),
itsBreed(breed)
{
    cout << "Dog(int, BREED) constructor..." << endl;
}
 
Dog::~Dog()
{
    cout << "Dog destructor..." << endl;
}
int main()
{
    Dog Fido;
    Dog rover(5);
    Dog buster(6,8);
    Dog yorkie (3,GOLDEN);
    Dog dobbie (4,20,DOBERMAN);
    Fido.Speak();
    rover.WagTail();
    cout << "Yorkie is " << yorkie.GetAge() 
         << " years old" << endl;
    cout << "Dobbie weighs ";
    cout << dobbie.GetWeight() << " pounds" << endl;
    return 0;
}