# include <stdio.h>
# include <stdbool.h>
//
//  Program 9.4, Stephen Kochan, Programming in C.
//
struct date
{
  int month;
  int day;
  int year;
};

int main ( void );
struct date dateUpdate ( struct date today );
int numberOfDays ( struct date d );
bool isLeapYear ( struct date d );

int main ( void )
{
  struct date thisDay, nextDay;

  printf ( "Enter today's date (mm dd yyyy): \n" );
  scanf ( "%i%i%i", &thisDay.month, &thisDay.day, &thisDay.year );

  nextDay = dateUpdate ( thisDay );

  printf ( "Tomorrow's date is is %i/%i/%.2i.\n", nextDay.month, nextDay.day,
    nextDay.year % 100 );

  return 0;
}
struct date dateUpdate ( struct date today )
{
  struct date tomorrow;

  if ( today.day != numberOfDays ( today ) )
  {
    tomorrow.day = today.day + 1;
    tomorrow.month = today.month;
    tomorrow.year = today.year;
  }
  else if ( today.month == 12 )
  {
    tomorrow.day = 1;
    tomorrow.month = 1;
    tomorrow.year = today.year + 1;
  }
  else
  {
    tomorrow.day = 1;
    tomorrow.month = today.month + 1;
    tomorrow.year = today.year;
  }
  return tomorrow;
}

int numberOfDays ( struct date d )
{
  int days;
  bool isLeapYear ( struct date d );
  const int daysPerMonth[12] = { 31, 28, 31, 30, 31, 30,
                                 31, 31, 30, 31, 30, 31 };

  if ( isLeapYear ( d ) == true && d.month == 2 )
  {
    days = 29;
  }
  else
  {
    days = daysPerMonth[d.month-1];
  }
  return days;
}
bool isLeapYear ( struct date d )
{
  bool leapYearFlag;

  if ( ( d.year % 4 == 0 && d.year % 100 != 0 ) ||
       ( d.year % 400 == 0 ) )
  {
    leapYearFlag = true;
  }
  else
  {
    leapYearFlag = false;
  }
  return leapYearFlag;
}