C++ Class Definition Add forward declaration of class

 
#include <iostream>
#include <iomanip>
using namespace std;
// forward declaration of class Intdate
class Intdate;/*from  www .j a va  2 s .  c  o  m*/
// declaration section for Date
class Date
{
   private:
   int month, day, year;
   public:
   Date(int = 7, int = 4, int = 2012);  // constructor
   operator Intdate();  // conversion operator from Date to Intdate
   void showDate();
};
class Intdate
{
   private:
   long yyyymmdd;
   public:
   Intdate(long = 0);    // constructor
   operator Date();  // conversion operator from Intdate to Date
   void showint();
};
// implementation section for Date
Date::Date(int mm, int dd, int yyyy)  // constructor
{
   month = mm;
   day = dd;
   year = yyyy;
}
// conversion operator function converting from Date to Intdate class
Date::operator Intdate()   // must return an Intdate object
{
   long temp;
   temp = year * 10000 + month * 100 + day;
   return(Intdate(temp));
}
// member function to display a Date
void Date::showDate()
{
   cout << setfill('0') << setw(2) << month << '/' << setw(2) << day << '/' << setw(2) << year % 100;
   return;
}
// implementation section for Intdate
Intdate::Intdate(long ymd)  // constructor
{
   yyyymmdd = ymd;
}
// conversion operator function converting from Intdate to Date class
Intdate::operator Date()   // must return a Date object
{
   int mo, da, yr;
   yr = int(yyyymmdd/10000.0);
   mo = int((yyyymmdd - yr * 10000.0)/100.0);
   da = int(yyyymmdd - yr * 10000.0 - mo * 100.0);
   return(Date(mo,da,yr));
}
// member function to display an Intdate
void Intdate::showint()
{
   cout << yyyymmdd;
   return;
}
int main()
{
   Date a(4,1,2012), b;      // declare two Date objects
   Intdate c(20121215L), d;  // declare two Intdate objects
   b = Date(c);      // cast c into a Date object
   d = Intdate(a);   // cast a into an Intdate object
   cout << " a's date is ";
   a.showDate();
   cout << "\n   as an Intdate object this date is ";
   d.showint();
   cout << "\n c's date is ";
   c.showint();
   cout << "\n   as a Date object this date is ";
   b.showDate();
   cout << endl;
   return 0;
}