doy.c
1.65 KB
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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2011-2012 Free Software Foundation, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General
Public License along with this library. If not, see
<http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <mailutils/datetime.h>
static int month_start[]=
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
/* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
31 28 31 30 31 30 31 31 30 31 30 31
*/
#define leap_year(y) ((y) % 4 == 0 && ((y) % 100 != 0 || (y) % 400 == 0))
/* Compute number of days since January 1 to the given day of year. */
int
mu_datetime_dayofyear (int year, int month, int day)
{
int leap, month_days;
if (year < 0 || month < 1 || month > 12 || day < 1)
return -1;
leap = leap_year (year);
month_days = month_start[month] - month_start[month - 1]
+ ((month == 2) ? leap : 0);
if (day > month_days)
return -1;
if (month <= 2)
leap = 0;
return month_start[month-1] + day + leap;
}