clean up g_date_time_get_week_day()

No functionality changes here.

Vastly simplify the algorithm for calculating the day of the week.

Fix the documentation (which is incorrectly stating that 1 means
Sunday) and clarify that the number we return is in line with ISO 8601
week day numbering.
This commit is contained in:
Ryan Lortie 2010-09-26 18:51:23 -04:00
parent e77faeb920
commit 1a0dbff236

View File

@ -1608,8 +1608,8 @@ g_date_time_get_week_of_year (GDateTime *datetime)
* g_date_time_get_day_of_week: * g_date_time_get_day_of_week:
* @datetime: a #GDateTime * @datetime: a #GDateTime
* *
* Retrieves the day of the week represented by @datetime within the gregorian * Retrieves the ISO 8601 day of the week represented by @datetime (1 is
* calendar. 1 is Sunday, 2 is Monday, etc. * Monday, 2 is Tuesday... 7 is Sunday).
* *
* Return value: the day of the week * Return value: the day of the week
* *
@ -1618,27 +1618,9 @@ g_date_time_get_week_of_year (GDateTime *datetime)
gint gint
g_date_time_get_day_of_week (GDateTime *datetime) g_date_time_get_day_of_week (GDateTime *datetime)
{ {
gint a, y, m,
year = 0,
month = 0,
day = 0,
dow;
g_return_val_if_fail (datetime != NULL, 0); g_return_val_if_fail (datetime != NULL, 0);
/* return (datetime->days - 1) % 7 + 1;
* See Calendar FAQ Section 2.6 for algorithm information
* http://www.tondering.dk/claus/cal/calendar29.txt
*/
g_date_time_get_ymd (datetime, &year, &month, &day);
a = (14 - month) / 12;
y = year - a;
m = month + (12 * a) - 2;
dow = ((day + y + (y / 4) - (y / 100) + (y / 400) + (31 * m) / 12) % 7);
/* 1 is Monday and 7 is Sunday */
return (dow == 0) ? 7 : dow;
} }
/* Day of year getter {{{1 */ /* Day of year getter {{{1 */