list1502.cpp

teach yourself C++ in 21 days 第五版

//Listing 15.2 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;

void TelepathicFunction();

int main()
{
   const int MaxCats = 5; int i;
   Cat *CatHouse[MaxCats];

   for (i = 0; i < MaxCats; i++)
   {
      CatHouse[i] = new Cat(i);
      TelepathicFunction();
   }

   for ( i = 0; i < MaxCats; i++)
   {
      delete CatHouse[i];
      TelepathicFunction();
   }
   return 0;
}

void TelepathicFunction()
{
   cout << "There are ";
   cout << Cat::HowManyCats << " cats alive!" << endl;
}