//
// This is example code from Chapter 10.9 "User-defined input operators" of
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//

#include <iostream>

using namespace std;

//------------------------------------------------------------------------------

enum class Month {
   jan=1, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec
      };

class Date {
public:
   Date() {}                                               // default constructor
   Date(int yy, Month mm, int dd) : y(yy), m(mm), d(dd) {} // constructor
   Month month() const { return m; }
   int   day()   const { return d; }
   int   year()  const { return y; }

private:
   int y;
   Month m;
   int d;
};

//------------------------------------------------------------------------------

istream& operator>>(istream& is, Date& dd)
{
   int y, m, d;
   char ch1, ch2, ch3, ch4;
   is >> ch1 >> y >> ch2 >> m >> ch3 >> d >> ch4;
   if (!is) return is;
   if (ch1!='(' || ch2!=',' || ch3!=',' || ch4!=')') {    // oops: format error
      is.clear(ios_base::failbit);
      return is;
   }
   dd = Date(y,Month(m),d);    // update dd
   return is;
}

//------------------------------------------------------------------------------

ostream& operator<<(ostream& os, const Date& d)
{
   return os << '(' << d.year()
             << ',' << int(d.month())
             << ',' << d.day() 
             << ')';
}

//------------------------------------------------------------------------------

int main()
{
   Date d;
   cout << "Enter date: ";
   cin  >> d;
   cout << endl << "d is " << d;
}

//------------------------------------------------------------------------------