list1005.cpp

teach yourself C++ in 21 days 第五版

// Listing 10.5 - 
// Copy constructors

#include <iostream>
using namespace std;

class Cat
{
  public:
    Cat();              // default constructor
    Cat (const Cat &);  // copy constructor
    ~Cat();             // destructor
    int GetAge()   const   { return *itsAge; }
    int GetWeight() const  { return *itsWeight; }
    void SetAge(int age)   { *itsAge = age; }

  private:
    int *itsAge;
    int *itsWeight;
};

Cat::Cat()
{
   itsAge = new int;
   itsWeight = new int;
   *itsAge = 5;
   *itsWeight = 9;
}

Cat::Cat(const Cat & rhs)
{
   itsAge = new int;
   itsWeight = new int;
   *itsAge = rhs.GetAge();  // public access
   *itsWeight = *(rhs.itsWeight); // private access
}

Cat::~Cat()
{
   delete itsAge;
   itsAge = 0;
   delete itsWeight;
   itsWeight = 0;
}

int main()
{
   Cat Frisky;
   cout << "Frisky's age: " << Frisky.GetAge() << endl;
   cout << "Setting Frisky to 6...\n";
   Frisky.SetAge(6);
   cout << "Creating Boots from Frisky\n";
   Cat Boots(Frisky);
   cout << "Frisky's age: " <<     Frisky.GetAge() << endl;
   cout << "Boots' age: " << Boots.GetAge() << endl;
   cout << "setting Frisky to 7...\n";
   Frisky.SetAge(7);
   cout << "Frisky's age: " <<     Frisky.GetAge() << endl;
   cout << "boot's age: " << Boots.GetAge() << endl;
   return 0;
}