typedef  int (__stdcall *CallbackFunction)(int nValue);
  

  

  class __declspec(dllexport) CXXX
  

  {
  

  public:
  

  XStitching( void );
  

  

  ~XStitching(void);
  

  private:
  

  CallbackFunction m_callback;
  

  };
 

  CXXX::CXXX()
  

  {
  

  m_callback = NULL;
  

  }
  

  

  CXXX::~CXXX()
  

  {
  

  if(m_callback != NULL)
  

  m_callback = NULL;
  

  

  }
 

  CXXX *cls=new CXXX();
  

  delete cls;