ISO 8601: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		ISO 8601 is a standard issued by the International Organization for Standardization (ISO) for the date and time. According to ISO 8601, the date is as follows:
2	2
3		-	~~` YYYY-MM-DD`~~
	3	+	```text
	4	+	YYYY-MM-DD
	5	+	```
4	6
5	7		where YYYY is a year in the Gregorian calendar , MM is a month between 01 (January) and 12 (December), and DD is the day of the month between 01 and 31.
6	8
7	9		The time is recorded:
8	10
9		-	~~` HH:MM:SS`~~
	11	+	```text
	12	+	HH:MM:SS
	13	+	```
10	14
11	15		where HH has hours after midnight between 00 and 23. The MM is minutes from the beginning of the previous hour between 00 and 59. The SS is seconds from the beginning of the previous minute between 00 and 59.
12	16
13	17		The combined date and time should be marked with the letter "T":
14	18
15		-	~~` YYYY-MM-DDTHH:MM:SS`~~
	19	+	```text
	20	+	YYYY-MM-DDTHH:MM:SS
	21	+	```
16	22
17	23		But often the intermediate letter "T" can be replaced by a space.
18	24
19	25		The time zone can be indicated by marking the time difference between the coordinated universal time (UTC) as follows:
20	26
21		-	~~` YYYY-MM-DDTHH:MM:SS±HH:MM`~~
	27	+	```text
	28	+	YYYY-MM-DDTHH:MM:SS±HH:MM
	29	+	```
22	30
23	31		## Useful functions
24	32
25	33		\| Function \| Description \| Unit \|
26	34		\|----\|----\|----\|
27	35		\| DayOfTheMonth \| Gives day of month index for a [[TDateTime]] value \| DateUtils \|
28	36		\| DayOfTheWeek \| Gives day of week index for a TDateTime value \| DateUtils \|
29	37		\| DayOfTheYear \| Gives the day of the year for a TDateTime value \| DateUtils \|
30	38		\| FormatDateTime \| Gives a string representation of a TDateTime value with a given format \| SysUtils \|
31	39		\| WeekOf \| Gives the week of the year for a TDateTime value \| DateUtils \|
32	40
33	41		## Example
34	42
35	43		``` pascal
36	44		program iso_8601_project;
37	45
38	46		Uses SysUtils,DateUtils;
39	47
40	48		// Combined date and time in UTC e.g // 2018-09-26T12:18:47Z
41	49		function ISO8601_Combined_date_and_time_in_UTC(a_DateTime: TDateTime; a_Time_zone:string):string;
42	50		begin
43	51		result := FormatDateTime( 'yyyy-mm-dd"T"hh:mm:ss', a_DateTime )+a_Time_zone;
44	52		end;
45	53
46	54		// Week: e.g. 2018-W39
47	55		function ISO8601_week(a_DateTime: TDateTime):string;
48	56		begin
49	57		result := FormatDateTime('yyyy', a_DateTime)+'-W' +
50	58		(WeekOf( a_DateTime )).ToString ;
51	59		end;
52	60
53	61		// Date with week number: e.g. 2018-W39-3
54	62		function ISO8601_Date_with_week_number(a_DateTime: TDateTime):string;
55	63		begin
56	64		result := FormatDateTime('yyyy', a_DateTime)+'-W' +
57	65		(WeekOf(a_DateTime)).ToString + '-' + (DayOfTheWeek(a_DateTime)).ToString ;
58	66		end;
59	67
60	68		// Ordinal date: e.g. 2018-269
61	69		function ISO8601_Ordinal_date(a_DateTime: TDateTime):string;
62	70		begin
63	71		result := FormatDateTime('yyyy', a_DateTime)+ '-'
64	72		+ (DayOfTheYear( a_DateTime )).ToString ;
65	73		end;
66	74
67	75		var
68	76		aDateTime: TDateTime;
69	77		begin
70	78		aDateTime := now;
71	79		WriteLn('Date: '+ FormatDateTime( 'yyyy-mm-dd', aDateTime )); // 2018-09-26
72	80		WriteLn('Combined date and time in UTC: ');
73	81		WriteLn(' ' + ISO8601_Combined_date_and_time_in_UTC(aDateTime,'+00:00')); // 2018-09-26T12:18:47+00:00
74	82		WriteLn(' ' + FormatDateTime( 'yyyymmdd"T"hhmmss', aDateTime )+'Z'); // 20180926T121847Z
75	83		Writeln(' ' + ISO8601_Combined_date_and_time_in_UTC(aDateTime,'Z')); //2018-09-26T12:18:47Z
76	84		WriteLn('Week: '+ ISO8601_week(aDateTime) ); // 2018-W39
77	85		WriteLn('Date with week number: '+ ISO8601_Date_with_week_number(aDateTime)); // 2018-W39-3
78	86		WriteLn('Ordinal date: '+ ISO8601_Ordinal_date(aDateTime)); // 2018-269
79	87		ReadLn;
80	88		end.
81	89		```
82	90
83	91		---
84	92		From the Free Pascal wiki, page "ISO 8601", as it stood on 2019-07-08 after a change by Djzepi, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).

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