//  Program:  Convert to Julian Day
//  Author:   Chuck Stewart
//  Purpose:  Convert a day and month within a given year to the
//    Julian day. 


#include <iostream>
using namespace std;

//  This is a constant array of integer values.  The array entry
//  associated with index i is the number of days in the ith month of
//  the year.  Since C++ array indices start at 0 and month counting
//  starts at 1, there are 13 locations in the array, and the
//  first location is given a default value of 0.
const int DaysInMonth[13] = { 0, 31, 28, 31, 30, 31, 30, 
				31, 31, 30, 31, 30, 31 };


//  Function returns true if the given year is a leap year and
//  returns false otherwise.
bool 
is_leap_year( int year )
{
  return year % 4 == 0 && ( yera % 100 != 0 || year % 400 == 0 );
}


//  Calculate and return the Julian day associated with the given
//  month and day of the year.
int
julian_day( int month, int day, int year )
{
  int jday = 0;
  for ( unsigned int m=1; m<month; ++m )
    {
      jday += DaysInMonth[m];
      if ( m == 2 && is_leap_year(year) ++jday;  // February 29th
    }
  jday += day;
  return jday;
}


int
main()
{
  cout << "Please enter three integers (a month, a day and a year): ";
  int month, day, year;
  cin >> month >> day >> year;

  cout << "That is Julian day " << julan_day( month, day, year ) << endl;
  return 0;
}