EN
C# / .NET - convert DateTime to iso 8601
14 points
In this article, we are going to show how in C# / .NET convert DateTime object to iso 8601 string.
Quick solution:
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using System;2
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public class Program4
{5
public static void Main()6
{7
DateTime time = DateTime.Now;8
DateTime utcTime = DateTime.UtcNow;9
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// when we want local time with offset11
Console.WriteLine(time.ToString("yyyy-MM-ddTHH:mm:sszzz")); // 2020-07-28T08:40:39+00:0012
13
// when we want world global time14
Console.WriteLine(utcTime.ToString("yyyy-MM-ddTHH:mm:ssZ")); // 2020-07-28T08:40:39Z15
}16
}Output:
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2020-07-28T08:40:39+00:002
2020-07-28T08:40:39Z
Look to the below to see full examples:
It is importnant to use invariant culture info to get proper formatted time from ToString() method.
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using System;2
using System.Globalization;3
4
public class Program5
{6
private static CultureInfo culture = CultureInfo.InvariantCulture;7
8
public static void Main()9
{10
DateTime time = DateTime.Now;11
DateTime utcTime = DateTime.UtcNow;12
13
// without time zone infomration14
Console.WriteLine(time.ToString("s", culture)); // 2020-05-22T21:08:4215
Console.WriteLine(utcTime.ToString("s", culture)); // 2020-05-22T21:08:4216
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// with time zone information (+/-HH:MM or Z)18
Console.WriteLine(time.ToString("o", culture)); // 2020-05-22T21:08:42.9082887+00:0019
Console.WriteLine(utcTime.ToString("o", culture)); // 2020-05-22T21:08:42.9082887Z20
}21
}Output:
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2020-05-22T21:08:422
2020-05-22T21:08:423
2020-05-22T21:08:42.9082887+00:004
2020-05-22T21:08:42.9082887ZThere are different formats of iso 8601 times.
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using System;2
3
public class Program4
{5
public static void Main()6
{7
DateTime time = DateTime.Now;8
9
Console.WriteLine(time.ToString("yyyy-MM-ddTHH:mm:sszzz")); // 2019-08-18T07:36:13+01:0010
Console.WriteLine(time.ToString("yyyyMMdd")); // 2019081811
Console.WriteLine(time.ToString("--MM-dd")); // --08-1812
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DateTime utcTime = DateTime.UtcNow;14
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Console.WriteLine(utcTime.ToString("yyyy-MM-ddTHH:mm:ssZ")); // 2019-08-18T06:36:13Z16
Console.WriteLine(utcTime.ToString("yyyyMMddTHHZ")); // 20190818T06Z17
}18
}19
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// ------------------------------------------------------21
// Check other custom formats at the end of this section.22
//Output:
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2019-08-18T07:36:13+01:002
2019-08-18T06:36:13Z3
20190818T06Z4
201908185
--08-18Note: date and time string with Z suffix should be based on DateTime.UtcNow. Check this link for more details.
Other custom formats:
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/*2
3
--[ To use with DateTime.Now ]----------------------4
FORMAT TEXT5
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yyyy-MM-ddTHH:mm:sszzz 2019-08-18T07:36:13+01:007
yyyy-MM-ddTHH:mm:sszz 2019-08-18T07:36:13+018
yyyy-MM-ddTHH:mm:ss 2019-08-18T07:36:139
yyyy-MM-ddTHH:mmzzz 2019-08-18T07:36+01:0010
yyyy-MM-ddTHH:mmzz 2019-08-18T07:36+0111
yyyy-MM-ddTHH:mm 2019-08-18T07:3612
yyyy-MM-ddTHHzzz 2019-08-18T07+01:0013
yyyy-MM-ddTHHzz 2019-08-18T07+0114
yyyy-MM-ddTHH 2019-08-18T0715
yyyy-MM-dd 2019-08-1816
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yyyyMMddTHHmmsszzz 20190818T073613+01:0018
yyyyMMddTHHmmsszz 20190818T073613+0119
yyyyMMddTHHmmzzz 20190818T0736+01:0020
yyyyMMddTHHmmzz 20190818T0736+0121
yyyyMMddTHHzzz 20190818T07+01:0022
yyyyMMddTHHzz 20190818T07+0123
yyyyMMddTHH 20190818T0724
yyyyMMdd 2019081825
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--MM-dd --08-1827
28
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--[ To use with DateTime.UtcNow ]-------------------30
FORMAT TEXT31
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yyyy-MM-ddTHH:mm:ssZ 2019-08-18T06:36:13Z33
yyyy-MM-ddTHH:mmZ 2019-08-18T06:36Z34
yyyy-MM-ddTHHZ 2019-08-18T06Z35
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yyyyMMddTHHmmssZ 20190818T063613Z37
yyyyMMddTHHmmZ 20190818T0636Z38
yyyyMMddTHHZ 20190818T06Z39
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*/In this section, custom method that returns a week or ordinal date is presented.
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using System;2
using System.Globalization;3
4
public static class ISO8601TimeUtils5
{6
public static string GetSimpleWeekDate(DateTime time)7
{8
CultureInfo culture = CultureInfo.InvariantCulture;9
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Calendar calendar = culture.Calendar;11
DateTimeFormatInfo format = culture.DateTimeFormat;12
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int week = calendar.GetWeekOfYear(time, format.CalendarWeekRule, format.FirstDayOfWeek);14
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return time.Year + "-W" + week;16
}17
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public static string GetExtendedWeekDate(DateTime time)19
{20
string week = GetSimpleWeekDate(time);21
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return week + "-" + (int)time.DayOfWeek;23
}24
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public static string GetOrdinalDate(DateTime time)26
{27
return time.Year + "-" + time.DayOfYear;28
}29
}30
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// Usage example:32
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public class Program34
{35
public static void Main()36
{37
DateTime time = DateTime.Now;38
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Console.WriteLine(ISO8601TimeUtils.GetExtendedWeekDate(time)); // 2019-W34-040
Console.WriteLine(ISO8601TimeUtils.GetSimpleWeekDate(time)); // 2019-W3441
Console.WriteLine(ISO8601TimeUtils.GetOrdinalDate(time)); // 2019-23042
}43
}Output:
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2019-W34-02
2019-W343
2019-230Note: above example returns different week number depending of Calendar.GetWeekOfYear() method configuration.
