16. Two-dimensional Array Example

#include <iostream>

// day_of_year: returns day of year:
int day_of_year( int month, int day, int year )
{
  // Table of the number of days in each month:
  static const int daytab[2][13] = {
    {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
    {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
  };

  int leap =
      year%4 == 0 && year%100 != 0 || year%400 == 0;

  for ( int i = 1; i < month; i++ ) {
      day += daytab[leap][i];
  }
  return day;
}

int main()
{
  for (;;) {
    int month;
    int day;
    int year;

    std::cout << "Enter M D Y: ";
    std::cin >> month;
    std::cin >> day;
    std::cin >> year;

    std::cout
        << "day of year: "
        << day_of_year( month, day, year )
        << std::endl
        ;
  }

  return 0;
}