class Date {

private:

  int day, month, year;

public:

  // reads a date (in dd mm yyyy format) from the specfied input stream.
  // if an error of any sort (bad read, invalid date) occurs, the input
  // stream is left in the failed state.
  void read (istream &is);

  // writes a date to the specified output stream (in dd/mm/yyyy format)
  void write (ostream &os) const;

  // moves a date the specified number of days forward (positive day
  // values) or backwards (negative day values)
  void move (int days);

};