int mdays ( int m )
//
//  Purpose:
//
//    MDAYS returns the number of days in any month in 2012.
//
//  Parameters:
//
//    Input, int M, the index of a month, between 1 and 12.
//
//    Output, int MDAYS, the number of days in the month.
//
{
  int days;

  if ( m == 1 || 
       m == 3 ||
       m == 5 ||
       m == 7 ||
       m == 8 ||
       m == 10 ||
       m == 12 )
  {
    days = 31;
  }
  else if ( m == 2 )
  {
    days = 29;
  }
  else if ( m == 4 ||
            m == 6 ||
            m == 9 ||
            m == 11 )
  {
    days = 30
  }
  else
  {
    printf ( "\n" );
    printf ( "MDAYS - Fatal error!\n" );
    printf ( "  The input month index M = %d is illegal\n", m );
    days = 0;
  }

  return days;
}