//
// Program to test "next_date" function.
//

#include <iostream.h>
#include <stdlib.h>

// "error_exit" function.
// Post:  "Bad input" printed; program exited.
// (Yes, this is extremely crude.)
void error_exit(void)
{
  cout << "Bad input\n";
  exit(EXIT_FAILURE);
}

// "next_date" function.
// Pre:  "day", "month", and "year" represent a date, e.g. 1/1/2000.
// Post:  Prints the next date, in month/day/year form.
void next_date(int day, int month, int year)
{
  // check year and month for acceptable values.
  if (year < 1) error_exit();
  if ((month < 1) || (month > 12)) error_exit();

  // calculate days in month.
  int days_in_month;
  // February
  if (month == 2)
    {
      // calculate number of days -- depends on whether a leap year.
      if ( ((year % 400) == 0) || 
	   (((year % 4) == 0) && ((year % 100) != 0)))
	days_in_month = 29;
      else
	days_in_month = 28;
    }
  // 30-day months (order in test based on "30 days hath September" :-) )
  else if ((month == 9) || (month == 4) || (month == 6)
	   || (month == 11))
    days_in_month = 30;
  // 31-day months
  else
    days_in_month = 31;

  // check day for acceptable value.
  if ((day < 1) || (day > days_in_month)) error_exit();

  // compute next day.
  day = day + 1;

  // next month?
  if (day > days_in_month)
    {
      month = month + 1;
      day = 1;
    }

  // next year?
  if (month > 12)
    {
      year = year + 1;
      month = 1;
    }

  // print result.
  cout << "next date, in month/day/year format:  "
       << month << "/" << day << "/" << year << endl;
}

int main(void)
{
  int d, m, y;
  cout << "Enter integers for month, day, year:\n";
  cin >> m >> d >> y;
  next_date(d, m, y);
  return EXIT_SUCCESS;
}