Listing 10 Hides the Date's data in an incomplete type

// date4.h

struct DateRep:

struct Date
{
   Date(int, int, int);
   ~Date();
   char *format(char *) const;
   int compare(const Date &) const;

private:
   struct DateRep *drep;

   static const char * month_text[13];
};

/* End of File */