1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
21 * Modified by the GLib Team and others 1997-1999. See the AUTHORS
22 * file for a list of people on the GLib Team. See the ChangeLog
23 * files for a list of changes. These files are distributed with
24 * GLib at ftp://ftp.gtk.org/pub/gtk/.
46 GDate *d = g_new0 (GDate, 1); /* happily, 0 is the invalid flag for everything. */
52 g_date_new_dmy (GDateDay day, GDateMonth m, GDateYear y)
55 g_return_val_if_fail (g_date_valid_dmy (day, m, y), NULL);
66 g_assert (g_date_valid (d));
72 g_date_new_julian (guint32 j)
75 g_return_val_if_fail (g_date_valid_julian (j), NULL);
84 g_assert (g_date_valid (d));
90 g_date_free (GDate *d)
92 g_return_if_fail (d != NULL);
98 g_date_valid (GDate *d)
100 g_return_val_if_fail (d != NULL, FALSE);
102 return (d->julian || d->dmy);
105 static const guint8 days_in_months[2][13] =
106 { /* error, jan feb mar apr may jun jul aug sep oct nov dec */
107 { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
108 { 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } /* leap year */
111 static const guint16 days_in_year[2][14] =
112 { /* 0, jan feb mar apr may jun jul aug sep oct nov dec */
113 { 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
114 { 0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
118 g_date_valid_month (GDateMonth m)
120 return ( (m > G_DATE_BAD_MONTH) && (m < 13) );
124 g_date_valid_year (GDateYear y)
126 return ( y > G_DATE_BAD_YEAR );
130 g_date_valid_day (GDateDay d)
132 return ( (d > G_DATE_BAD_DAY) && (d < 32) );
136 g_date_valid_weekday (GDateWeekday w)
138 return ( (w > G_DATE_BAD_WEEKDAY) && (w < 8) );
142 g_date_valid_julian (guint32 j)
144 return (j > G_DATE_BAD_JULIAN);
148 g_date_valid_dmy (GDateDay d,
152 return ( (m > G_DATE_BAD_MONTH) &&
154 (d > G_DATE_BAD_DAY) &&
155 (y > G_DATE_BAD_YEAR) && /* must check before using g_date_is_leap_year */
156 (d <= (g_date_is_leap_year (y) ?
157 days_in_months[1][m] : days_in_months[0][m])) );
161 /* "Julian days" just means an absolute number of days, where Day 1 ==
165 g_date_update_julian (GDate *d)
170 g_return_if_fail (d != NULL);
171 g_return_if_fail (d->dmy);
172 g_return_if_fail (!d->julian);
173 g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
175 /* What we actually do is: multiply years * 365 days in the year,
176 * add the number of years divided by 4, subtract the number of
177 * years divided by 100 and add the number of years divided by 400,
178 * which accounts for leap year stuff. Code from Steffen Beyer's
182 year = d->year - 1; /* we know d->year > 0 since it's valid */
184 d->julian_days = year * 365U;
185 d->julian_days += (year >>= 2); /* divide by 4 and add */
186 d->julian_days -= (year /= 25); /* divides original # years by 100 */
187 d->julian_days += year >> 2; /* divides by 4, which divides original by 400 */
189 index = g_date_is_leap_year (d->year) ? 1 : 0;
191 d->julian_days += days_in_year[index][d->month] + d->day;
193 g_return_if_fail (g_date_valid_julian (d->julian_days));
199 g_date_update_dmy (GDate *d)
205 guint32 A, B, C, D, E, M;
207 g_return_if_fail (d != NULL);
208 g_return_if_fail (d->julian);
209 g_return_if_fail (!d->dmy);
210 g_return_if_fail (g_date_valid_julian (d->julian_days));
212 /* Formula taken from the Calendar FAQ; the formula was for the
213 * Julian Period which starts on 1 January 4713 BC, so we add
214 * 1,721,425 to the number of days before doing the formula.
216 * I'm sure this can be simplified for our 1 January 1 AD period
217 * start, but I can't figure out how to unpack the formula.
220 A = d->julian_days + 1721425 + 32045;
221 B = ( 4 *(A + 36524) )/ 146097 - 1;
222 C = A - (146097 * B)/4;
223 D = ( 4 * (C + 365) ) / 1461 - 1;
224 E = C - ((1461*D) / 4);
225 M = (5 * (E - 1) + 2)/153;
227 m = M + 3 - (12*(M/10));
228 day = E - (153*M + 2)/5;
229 y = 100 * B + D - 4800 + (M/10);
231 #ifdef G_ENABLE_DEBUG
232 if (!g_date_valid_dmy (day, m, y))
234 g_warning ("\nOOPS julian: %u computed dmy: %u %u %u\n",
235 d->julian_days, day, m, y);
247 g_date_weekday (GDate *d)
249 g_return_val_if_fail (d != NULL, G_DATE_BAD_WEEKDAY);
250 g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_WEEKDAY);
254 g_date_update_julian (d);
256 g_return_val_if_fail (d->julian, G_DATE_BAD_WEEKDAY);
258 return ((d->julian_days - 1) % 7) + 1;
262 g_date_month (GDate *d)
264 g_return_val_if_fail (d != NULL, G_DATE_BAD_MONTH);
265 g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_MONTH);
269 g_date_update_dmy (d);
271 g_return_val_if_fail (d->dmy, G_DATE_BAD_MONTH);
277 g_date_year (GDate *d)
279 g_return_val_if_fail (d != NULL, G_DATE_BAD_YEAR);
280 g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_YEAR);
284 g_date_update_dmy (d);
286 g_return_val_if_fail (d->dmy, G_DATE_BAD_YEAR);
292 g_date_day (GDate *d)
294 g_return_val_if_fail (d != NULL, G_DATE_BAD_DAY);
295 g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_DAY);
299 g_date_update_dmy (d);
301 g_return_val_if_fail (d->dmy, G_DATE_BAD_DAY);
307 g_date_julian (GDate *d)
309 g_return_val_if_fail (d != NULL, G_DATE_BAD_JULIAN);
310 g_return_val_if_fail (g_date_valid (d), G_DATE_BAD_JULIAN);
314 g_date_update_julian (d);
316 g_return_val_if_fail (d->julian, G_DATE_BAD_JULIAN);
318 return d->julian_days;
322 g_date_day_of_year (GDate *d)
326 g_return_val_if_fail (d != NULL, 0);
327 g_return_val_if_fail (g_date_valid (d), 0);
331 g_date_update_dmy (d);
333 g_return_val_if_fail (d->dmy, 0);
335 index = g_date_is_leap_year (d->year) ? 1 : 0;
337 return (days_in_year[index][d->month] + d->day);
341 g_date_monday_week_of_year (GDate *d)
347 g_return_val_if_fail (d != NULL, 0);
348 g_return_val_if_fail (g_date_valid (d), 0);
352 g_date_update_dmy (d);
354 g_return_val_if_fail (d->dmy, 0);
356 g_date_clear (&first, 1);
358 g_date_set_dmy (&first, 1, 1, d->year);
360 wd = g_date_weekday (&first) - 1; /* make Monday day 0 */
361 day = g_date_day_of_year (d) - 1;
363 return ((day + wd)/7U + (wd == 0 ? 1 : 0));
367 g_date_sunday_week_of_year (GDate *d)
373 g_return_val_if_fail (d != NULL, 0);
374 g_return_val_if_fail (g_date_valid (d), 0);
378 g_date_update_dmy (d);
380 g_return_val_if_fail (d->dmy, 0);
382 g_date_clear (&first, 1);
384 g_date_set_dmy (&first, 1, 1, d->year);
386 wd = g_date_weekday (&first);
387 if (wd == 7) wd = 0; /* make Sunday day 0 */
388 day = g_date_day_of_year (d) - 1;
390 return ((day + wd)/7U + (wd == 0 ? 1 : 0));
394 g_date_clear (GDate *d, guint ndates)
396 g_return_if_fail (d != NULL);
397 g_return_if_fail (ndates != 0);
399 memset (d, 0x0, ndates*sizeof (GDate));
402 G_LOCK_DEFINE_STATIC (g_date_global);
404 /* These are for the parser, output to the user should use *
405 * g_date_strftime () - this creates more never-freed memory to annoy
406 * all those memory debugger users. :-)
409 static gchar *long_month_names[13] =
411 "Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
414 static gchar *short_month_names[13] =
416 "Error", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
419 /* This tells us if we need to update the parse info */
420 static gchar *current_locale = NULL;
422 /* order of these in the current locale */
423 static GDateDMY dmy_order[3] =
425 G_DATE_DAY, G_DATE_MONTH, G_DATE_YEAR
428 /* Where to chop two-digit years: i.e., for the 1930 default, numbers
429 * 29 and below are counted as in the year 2000, numbers 30 and above
430 * are counted as in the year 1900.
433 static GDateYear twodigit_start_year = 1930;
435 /* It is impossible to enter a year between 1 AD and 99 AD with this
438 static gboolean using_twodigit_years = FALSE;
440 struct _GDateParseTokens {
446 typedef struct _GDateParseTokens GDateParseTokens;
450 /* HOLDS: g_date_global_lock */
452 g_date_fill_parse_tokens (const gchar *str, GDateParseTokens *pt)
454 gchar num[4][NUM_LEN+1];
458 /* We count 4, but store 3; so we can give an error
461 num[0][0] = num[1][0] = num[2][0] = num[3][0] = '\0';
465 while (*s && pt->num_ints < 4)
469 while (*s && isdigit (*s) && i <= NUM_LEN)
471 num[pt->num_ints][i] = *s;
478 num[pt->num_ints][i] = '\0';
482 if (*s == '\0') break;
487 pt->n[0] = pt->num_ints > 0 ? atoi (num[0]) : 0;
488 pt->n[1] = pt->num_ints > 1 ? atoi (num[1]) : 0;
489 pt->n[2] = pt->num_ints > 2 ? atoi (num[2]) : 0;
491 pt->month = G_DATE_BAD_MONTH;
493 if (pt->num_ints < 3)
498 strncpy (lcstr, str, 127);
503 if (long_month_names[i] != NULL)
505 const gchar *found = strstr (lcstr, long_month_names[i]);
514 if (short_month_names[i] != NULL)
516 const gchar *found = strstr (lcstr, short_month_names[i]);
530 /* HOLDS: g_date_global_lock */
532 g_date_prepare_to_parse (const gchar *str, GDateParseTokens *pt)
534 const gchar *locale = setlocale (LC_TIME, NULL);
535 gboolean recompute_localeinfo = FALSE;
538 g_return_if_fail (locale != NULL); /* should not happen */
540 g_date_clear (&d, 1); /* clear for scratch use */
542 if ( (current_locale == NULL) || (strcmp (locale, current_locale) != 0) )
544 recompute_localeinfo = TRUE; /* Uh, there used to be a reason for the temporary */
547 if (recompute_localeinfo)
550 GDateParseTokens testpt;
553 g_free (current_locale); /* still works if current_locale == NULL */
555 current_locale = g_strdup (locale);
559 g_date_set_dmy (&d, 1, i, 1);
561 g_return_if_fail (g_date_valid (&d));
563 g_date_strftime (buf, 127, "%b", &d);
564 g_free (short_month_names[i]);
566 short_month_names[i] = g_strdup (buf);
570 g_date_strftime (buf, 127, "%B", &d);
571 g_free (long_month_names[i]);
573 long_month_names[i] = g_strdup (buf);
578 /* Determine DMY order */
580 /* had to pick a random day - don't change this, some strftimes
581 * are broken on some days, and this one is good so far. */
582 g_date_set_dmy (&d, 4, 7, 1976);
584 g_date_strftime (buf, 127, "%x", &d);
586 g_date_fill_parse_tokens (buf, &testpt);
589 while (i < testpt.num_ints)
594 dmy_order[i] = G_DATE_MONTH;
597 dmy_order[i] = G_DATE_DAY;
600 using_twodigit_years = TRUE; /* FALL THRU */
602 dmy_order[i] = G_DATE_YEAR;
605 /* leave it unchanged */
611 #ifdef G_ENABLE_DEBUG
613 g_message ("**GDate prepared a new set of locale-specific parse rules.");
619 g_message (" %s %s", long_month_names[i], short_month_names[i]);
623 if (using_twodigit_years)
626 g_message ("**Using twodigit years with cutoff year: %u", twodigit_start_year);
634 switch (dmy_order[i])
637 strings[i] = "Month";
652 g_message ("**Order: %s, %s, %s", strings[0], strings[1], strings[2]);
653 g_message ("**Sample date in this locale: `%s'", buf);
659 g_date_fill_parse_tokens (str, pt);
663 g_date_set_parse (GDate *d,
667 guint m = G_DATE_BAD_MONTH, day = G_DATE_BAD_DAY, y = G_DATE_BAD_YEAR;
669 g_return_if_fail (d != NULL);
674 G_LOCK (g_date_global);
676 g_date_prepare_to_parse (str, &pt);
678 #ifdef G_ENABLE_DEBUG
680 g_message ("Found %d ints, `%d' `%d' `%d' and written out month %d",
681 pt.num_ints, pt.n[0], pt.n[1], pt.n[2], pt.month);
686 if (pt.num_ints == 4)
688 G_UNLOCK (g_date_global);
689 return; /* presumably a typo; bail out. */
697 g_assert (pt.num_ints < 4); /* i.e., it is 2 or 3 */
699 while (i < pt.num_ints && j < 3)
701 switch (dmy_order[j])
705 if (pt.num_ints == 2 && pt.month != G_DATE_BAD_MONTH)
708 ++j; /* skip months, but don't skip this number */
717 if (pt.num_ints == 2 && pt.month == G_DATE_BAD_MONTH)
720 ++j; /* skip days, since we may have month/year */
730 if (using_twodigit_years && y < 100)
732 guint two = twodigit_start_year % 100;
733 guint century = (twodigit_start_year / 100) * 100;
751 if (pt.num_ints == 3 && !g_date_valid_dmy (day, m, y))
758 if (using_twodigit_years && y < 100)
759 y = G_DATE_BAD_YEAR; /* avoids ambiguity */
762 else if (pt.num_ints == 1)
764 if (pt.month != G_DATE_BAD_MONTH)
766 /* Month name and year? */
773 /* Try yyyymmdd and yymmdd */
775 m = (pt.n[0]/100) % 100;
779 /* FIXME move this into a separate function */
780 if (using_twodigit_years && y < 100)
782 guint two = twodigit_start_year % 100;
783 guint century = (twodigit_start_year / 100) * 100;
793 /* See if we got anything valid out of all this. */
794 /* y < 8000 is to catch 19998 style typos; the library is OK up to 65535 or so */
795 if (y < 8000 && g_date_valid_dmy (day, m, y))
802 #ifdef G_ENABLE_DEBUG
804 g_message ("Rejected DMY %u %u %u", day, m, y);
806 G_UNLOCK (g_date_global);
810 g_date_set_time (GDate *d,
816 g_return_if_fail (d != NULL);
818 #ifdef HAVE_LOCALTIME_R
819 localtime_r (&t, &tm);
822 struct tm *ptm = localtime (&t);
824 memcpy ((void *) &tm, (void *) ptm, sizeof(struct tm));
830 d->month = tm.tm_mon + 1;
832 d->year = tm.tm_year + 1900;
834 g_return_if_fail (g_date_valid_dmy (d->day, d->month, d->year));
840 g_date_set_month (GDate *d,
843 g_return_if_fail (d != NULL);
844 g_return_if_fail (g_date_valid_month (m));
846 if (d->julian && !d->dmy) g_date_update_dmy(d);
851 if (g_date_valid_dmy (d->day, d->month, d->year))
858 g_date_set_day (GDate *d,
861 g_return_if_fail (d != NULL);
862 g_return_if_fail (g_date_valid_day (day));
864 if (d->julian && !d->dmy) g_date_update_dmy(d);
869 if (g_date_valid_dmy (d->day, d->month, d->year))
876 g_date_set_year (GDate *d,
879 g_return_if_fail (d != NULL);
880 g_return_if_fail (g_date_valid_year (y));
882 if (d->julian && !d->dmy) g_date_update_dmy(d);
887 if (g_date_valid_dmy (d->day, d->month, d->year))
894 g_date_set_dmy (GDate *d,
899 g_return_if_fail (d != NULL);
900 g_return_if_fail (g_date_valid_dmy (day, m, y));
912 g_date_set_julian (GDate *d, guint32 j)
914 g_return_if_fail (d != NULL);
915 g_return_if_fail (g_date_valid_julian (j));
924 g_date_is_first_of_month (GDate *d)
926 g_return_val_if_fail (d != NULL, FALSE);
927 g_return_val_if_fail (g_date_valid (d), FALSE);
931 g_date_update_dmy (d);
933 g_return_val_if_fail (d->dmy, FALSE);
935 if (d->day == 1) return TRUE;
940 g_date_is_last_of_month (GDate *d)
944 g_return_val_if_fail (d != NULL, FALSE);
945 g_return_val_if_fail (g_date_valid (d), FALSE);
949 g_date_update_dmy (d);
951 g_return_val_if_fail (d->dmy, FALSE);
953 index = g_date_is_leap_year (d->year) ? 1 : 0;
955 if (d->day == days_in_months[index][d->month]) return TRUE;
960 g_date_add_days (GDate *d, guint ndays)
962 g_return_if_fail (d != NULL);
963 g_return_if_fail (g_date_valid (d));
967 g_date_update_julian (d);
969 g_return_if_fail (d->julian);
971 d->julian_days += ndays;
976 g_date_subtract_days (GDate *d, guint ndays)
978 g_return_if_fail (d != NULL);
979 g_return_if_fail (g_date_valid (d));
983 g_date_update_julian (d);
985 g_return_if_fail (d->julian);
986 g_return_if_fail (d->julian_days > ndays);
988 d->julian_days -= ndays;
993 g_date_add_months (GDate *d,
999 g_return_if_fail (d != NULL);
1000 g_return_if_fail (g_date_valid (d));
1004 g_date_update_dmy (d);
1006 g_return_if_fail (d->dmy);
1008 nmonths += d->month - 1;
1011 months = nmonths%12;
1013 d->month = months + 1;
1016 index = g_date_is_leap_year (d->year) ? 1 : 0;
1018 if (d->day > days_in_months[index][d->month])
1019 d->day = days_in_months[index][d->month];
1023 g_return_if_fail (g_date_valid (d));
1027 g_date_subtract_months (GDate *d,
1030 guint years, months;
1033 g_return_if_fail (d != NULL);
1034 g_return_if_fail (g_date_valid (d));
1038 g_date_update_dmy (d);
1040 g_return_if_fail (d->dmy);
1043 months = nmonths%12;
1045 g_return_if_fail (d->year > years);
1049 if (d->month > months) d->month -= months;
1053 d->month = 12 - months;
1057 index = g_date_is_leap_year (d->year) ? 1 : 0;
1059 if (d->day > days_in_months[index][d->month])
1060 d->day = days_in_months[index][d->month];
1064 g_return_if_fail (g_date_valid (d));
1068 g_date_add_years (GDate *d,
1071 g_return_if_fail (d != NULL);
1072 g_return_if_fail (g_date_valid (d));
1076 g_date_update_dmy (d);
1078 g_return_if_fail (d->dmy);
1082 if (d->month == 2 && d->day == 29)
1084 if (!g_date_is_leap_year (d->year))
1094 g_date_subtract_years (GDate *d,
1097 g_return_if_fail (d != NULL);
1098 g_return_if_fail (g_date_valid (d));
1102 g_date_update_dmy (d);
1104 g_return_if_fail (d->dmy);
1105 g_return_if_fail (d->year > nyears);
1109 if (d->month == 2 && d->day == 29)
1111 if (!g_date_is_leap_year (d->year))
1122 g_date_is_leap_year (GDateYear year)
1124 g_return_val_if_fail (g_date_valid_year (year), FALSE);
1126 return ( (((year % 4) == 0) && ((year % 100) != 0)) ||
1127 (year % 400) == 0 );
1131 g_date_days_in_month (GDateMonth month,
1136 g_return_val_if_fail (g_date_valid_year (year), 0);
1137 g_return_val_if_fail (g_date_valid_month (month), 0);
1139 index = g_date_is_leap_year (year) ? 1 : 0;
1141 return days_in_months[index][month];
1145 g_date_monday_weeks_in_year (GDateYear year)
1149 g_return_val_if_fail (g_date_valid_year (year), 0);
1151 g_date_clear (&d, 1);
1152 g_date_set_dmy (&d, 1, 1, year);
1153 if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1154 g_date_set_dmy (&d, 31, 12, year);
1155 if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1156 if (g_date_is_leap_year (year))
1158 g_date_set_dmy (&d, 2, 1, year);
1159 if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1160 g_date_set_dmy (&d, 30, 12, year);
1161 if (g_date_weekday (&d) == G_DATE_MONDAY) return 53;
1167 g_date_sunday_weeks_in_year (GDateYear year)
1171 g_return_val_if_fail (g_date_valid_year (year), 0);
1173 g_date_clear (&d, 1);
1174 g_date_set_dmy (&d, 1, 1, year);
1175 if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1176 g_date_set_dmy (&d, 31, 12, year);
1177 if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1178 if (g_date_is_leap_year (year))
1180 g_date_set_dmy (&d, 2, 1, year);
1181 if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1182 g_date_set_dmy (&d, 30, 12, year);
1183 if (g_date_weekday (&d) == G_DATE_SUNDAY) return 53;
1189 g_date_compare (GDate *lhs,
1192 g_return_val_if_fail (lhs != NULL, 0);
1193 g_return_val_if_fail (rhs != NULL, 0);
1194 g_return_val_if_fail (g_date_valid (lhs), 0);
1195 g_return_val_if_fail (g_date_valid (rhs), 0);
1197 /* Remember the self-comparison case! I think it works right now. */
1202 if (lhs->julian && rhs->julian)
1204 if (lhs->julian_days < rhs->julian_days) return -1;
1205 else if (lhs->julian_days > rhs->julian_days) return 1;
1208 else if (lhs->dmy && rhs->dmy)
1210 if (lhs->year < rhs->year) return -1;
1211 else if (lhs->year > rhs->year) return 1;
1214 if (lhs->month < rhs->month) return -1;
1215 else if (lhs->month > rhs->month) return 1;
1218 if (lhs->day < rhs->day) return -1;
1219 else if (lhs->day > rhs->day) return 1;
1228 if (!lhs->julian) g_date_update_julian (lhs);
1229 if (!rhs->julian) g_date_update_julian (rhs);
1230 g_return_val_if_fail (lhs->julian, 0);
1231 g_return_val_if_fail (rhs->julian, 0);
1235 return 0; /* warnings */
1240 g_date_to_struct_tm (GDate *d,
1245 g_return_if_fail (d != NULL);
1246 g_return_if_fail (g_date_valid (d));
1247 g_return_if_fail (tm != NULL);
1251 g_date_update_dmy (d);
1253 g_return_if_fail (d->dmy);
1255 /* zero all the irrelevant fields to be sure they're valid */
1257 /* On Linux and maybe other systems, there are weird non-POSIX
1258 * fields on the end of struct tm that choke strftime if they
1259 * contain garbage. So we need to 0 the entire struct, not just the
1260 * fields we know to exist.
1263 memset (tm, 0x0, sizeof (struct tm));
1265 tm->tm_mday = d->day;
1266 tm->tm_mon = d->month - 1; /* 0-11 goes in tm */
1267 tm->tm_year = ((int)d->year) - 1900; /* X/Open says tm_year can be negative */
1269 day = g_date_weekday (d);
1270 if (day == 7) day = 0; /* struct tm wants days since Sunday, so Sunday is 0 */
1272 tm->tm_wday = (int)day;
1274 tm->tm_yday = g_date_day_of_year (d) - 1; /* 0 to 365 */
1275 tm->tm_isdst = -1; /* -1 means "information not available" */
1279 g_date_strftime (gchar *s,
1281 const gchar *format,
1287 g_return_val_if_fail (d != NULL, 0);
1288 g_return_val_if_fail (g_date_valid (d), 0);
1289 g_return_val_if_fail (slen > 0, 0);
1290 g_return_val_if_fail (format != 0, 0);
1291 g_return_val_if_fail (s != 0, 0);
1293 g_date_to_struct_tm (d, &tm);
1295 retval = strftime (s, slen, format, &tm);
1298 /* If retval == 0, the contents of s are undefined. We define