// singleton

#include <iostream>

class singleton
{
public:
  static singleton* getInstance()
  {
    ++refCount;
    std::cout << "\n  refCount = " << refCount;
    if(pInstance == 0)
      return (pInstance = new singleton);
    else
      return pInstance;
  }
  void release()
  { 
    if(refCount == 0) return;
    if(--refCount == 0)
    {
      std::cout << "\n  deleting instance";
      delete this;
    }
    std::cout << "\n  refCount = " << refCount;
  }
  void say()
  {
    std::cout << "singleton reference #" << refCount;
  }
private:
  singleton() {}
  ~singleton() { pInstance = 0; }
  static singleton *pInstance;
  static int refCount;
};

singleton* singleton::pInstance = 0;
int        singleton::refCount  = 0;

int main()
{
  singleton *pI1 = singleton::getInstance();
  singleton *pI2 = singleton::getInstance();
  
  std::cout << "\n  address of 1st reference = " << pI1;
  std::cout << "\n  address of 2nd reference = " << pI2;

  pI1->release();
  pI2->release();

  singleton* pI3 = singleton::getInstance();
  std::cout << "\n  address of 3rd reference = " << pI1;
  pI3->release();

  std::cout << "\n\n";
  return 0;
}