list1501.cpp

teach yourself C++ in 21 days 第五版

//Listing 15.1 static data members

#include <iostream>
using namespace std;

class Cat
{
  public:
    Cat(int age):itsAge(age){HowManyCats++; }
    virtual ~Cat() { HowManyCats--; }
    virtual int GetAge() { return itsAge; }
    virtual void SetAge(int age) { itsAge = age; }
    static int HowManyCats;

  private:
    int itsAge;

};

int Cat::HowManyCats = 0;

int main()
{
   const int MaxCats = 5; int i;
   Cat *CatHouse[MaxCats];
   for (i = 0; i<MaxCats; i++)
      CatHouse[i] = new Cat(i);

   for (i = 0; i<MaxCats; i++)
   {
      cout << "There are ";
      cout << Cat::HowManyCats;
      cout << " cats left!" << endl;
      cout << "Deleting the one that is ";
      cout << CatHouse[i]->GetAge();
      cout << " years old" << endl;
      delete CatHouse[i];
      CatHouse[i] = 0;
   }
   return 0;
}