Given a DateTime object how do I get an ISO 8601 date in string format

Question

Given   DateTime UtcNow   How do I get a string which represents the same value in an ISO 8601-compliant format   Note that ISO 8601 defines a number of similar formats  The specific format I am looking for is   yyyy-MM-ddTHH mm ssZ

User · Answer

To convert DateTime UtcNow to a string representation of yyyy-MM-ddTHH mm ssZ  you can use the ToString   method of the DateTime structure with a custom formatting string  When using custom format strings with a DateTime  it is important to remember that you need to escape your seperators using single quotes   The following will return the string represention you wanted   DateTime UtcNow ToString  yyyy - MM - dd T HH   mm   ss Z    DateTimeFormatInfo InvariantInfo

User · Answer

To convert DateTime UtcNow to a string representation of yyyy-MM-ddTHH mm ssZ  you can use the ToString   method of the DateTime structure with a custom formatting string  When using custom format strings with a DateTime  it is important to remember that you need to escape your seperators using single quotes   The following will return the string represention you wanted   DateTime UtcNow ToString  yyyy - MM - dd T HH   mm   ss Z    DateTimeFormatInfo InvariantInfo

User · Answer

System DateTime UtcNow ToString  o         val it   string    2013-10-13T13 03 50 2950037Z

User · Answer

Surprised that no one suggested it   System DateTime UtcNow ToString  u   Replace      T       Using PowerShell Core to demo    Lowercase  u  format  System DateTime   UtcNow ToString  u    gt  2020-02-06 01 00 32Z    Lowercase  u  format with replacement  System DateTime   UtcNow ToString  u   Replace      T    gt  2020-02-06T01 00 32Z    The UniversalSortableDateTimePattern gets you almost all the way to what you want  which is more an RFC 3339 representation      Added  I decided to use the benchmarks that were in answer https   stackoverflow com a 43793679 653058 to compare how this performs   tl dr  it s at the expensive end but still just a little over half a millisecond on my crappy old laptop  -   Implementation    Benchmark  public string ReplaceU        var text   dateTime ToUniversalTime   ToString  u   Replace       T       return text      Results        Summary    BenchmarkDotNet v0 11 5  OS Windows 10 0 19002 Intel Xeon CPU E3-1245 v3 3 40GHz  1 CPU  8 logical and 4 physical cores  NET Core SDK 3 0 100    Host         NET Core 3 0 0  CoreCLR 4 700 19 46205  CoreFX 4 700 19 46214   64bit RyuJIT   DefaultJob    NET Core 3 0 0  CoreCLR 4 700 19 46205  CoreFX 4 700 19 46214   64bit RyuJIT                   Method       Mean       Error      StdDev    ---------------------  ---------  ----------  ----------               CustomDev1   562 4 ns   11 135 ns   10 936 ns               CustomDev2   525 3 ns    3 322 ns    3 107 ns         CustomDev2WithMS   609 9 ns    9 427 ns    8 356 ns                  FormatO   356 6 ns    6 008 ns    5 620 ns                  FormatS   589 3 ns    7 012 ns    6 216 ns           FormatS Verify   599 8 ns   12 054 ns   11 275 ns            CustomFormatK   549 3 ns    4 911 ns    4 594 ns     CustomFormatK Verify   539 9 ns    2 917 ns    2 436 ns                 ReplaceU   615 5 ns   12 313 ns   11 517 ns         Hints   Outliers   BenchmarkDateTimeFormat CustomDev2WithMS  Default     - gt  1 outlier  was  removed  668 16 ns    BenchmarkDateTimeFormat FormatS  Default              - gt  1 outlier  was  removed  621 28 ns    BenchmarkDateTimeFormat CustomFormatK  Default        - gt  1 outlier  was  detected  542 55 ns    BenchmarkDateTimeFormat CustomFormatK Verify  Default - gt  2 outliers were removed  557 07 ns  560 95 ns        Legends     Mean     Arithmetic mean of all measurements   Error    Half of 99 9  confidence interval   StdDev   Standard deviation of all measurements   1 ns     1 Nanosecond  0 000000001 sec            BenchmarkRunner  End

User · Answer

If you re developing under SharePoint 2010 or higher you can use  using Microsoft SharePoint  using Microsoft SharePoint Utilities      string strISODate   SPUtility CreateISO8601DateTimeFromSystemDateTime DateTime Now

User · Answer

Use   private void TimeFormats         DateTime localTime   DateTime Now      DateTime utcTime   DateTime UtcNow      DateTimeOffset localTimeAndOffset   new DateTimeOffset localTime  TimeZoneInfo Local GetUtcOffset localTime           UTC     string strUtcTime o   utcTime ToString  o        string strUtcTime s   utcTime ToString  s        string strUtcTime custom   utcTime ToString  yyyy-MM-ddTHH mm ssK           Local     string strLocalTimeAndOffset o   localTimeAndOffset ToString  o        string strLocalTimeAndOffset s   localTimeAndOffset ToString  s        string strLocalTimeAndOffset custom   utcTime ToString  yyyy-MM-ddTHH mm ssK           Output     Response Write   lt br  gt UTC lt br  gt         Response Write  strUtcTime o      strUtcTime o     lt br  gt         Response Write  strUtcTime s      strUtcTime s     lt br  gt         Response Write  strUtcTime custom      strUtcTime custom     lt br  gt          Response Write   lt br  gt Local Time lt br  gt         Response Write  strLocalTimeAndOffset o      strLocalTimeAndOffset o     lt br  gt         Response Write  strLocalTimeAndOffset s      strLocalTimeAndOffset s     lt br  gt         Response Write  strLocalTimeAndOffset custom      strLocalTimeAndOffset custom     lt br  gt          OUTPUT  UTC     strUtcTime o  2012-09-17T22 02 51 4021600Z     strUtcTime s  2012-09-17T22 02 51     strUtcTime custom  2012-09-17T22 02 51Z  Local Time     strLocalTimeAndOffset o  2012-09-17T15 02 51 4021600-07 00     strLocalTimeAndOffset s  2012-09-17T15 02 51     strLocalTimeAndOffset custom  2012-09-17T22 02 51Z   Sources    Standard Date and Time Format Strings  MSDN  Custom Date and Time Format Strings  MSDN

User · Answer

I would just use XmlConvert   XmlConvert ToString DateTime UtcNow  XmlDateTimeSerializationMode RoundtripKind     It will automatically preserve the time zone

User · Answer

DateTime UtcNow ToString  s     Returns something like 2008-04-10T06 30 00  UtcNow obviously returns a UTC time so there is no harm in   string Concat DateTime UtcNow ToString  s     Z

User · Answer

As mentioned in other answer  DateTime has issues by design   NodaTime  I suggest to use NodaTime to manage date time values    Local time  date  datetime Global time Time with timezone Period Duration   Formatting  So  to create and format ZonedDateTime you can use the following code snippet   var instant1   Instant FromUtc 2020  06  29  10  15  22    var utcZonedDateTime   new ZonedDateTime instant1  DateTimeZone Utc   utcZonedDateTime ToString  yyyy-MM-ddTHH mm ss Z    CultureInfo InvariantCulture      2020-06-29T10 15 22Z   var instant2   Instant FromDateTimeUtc new DateTime 2020  06  29  10  15  22  DateTimeKind Utc     var amsterdamZonedDateTime   new ZonedDateTime instant2  DateTimeZoneProviders Tzdb  Europe Amsterdam     amsterdamZonedDateTime ToString  yyyy-MM-ddTHH mm ss Z    CultureInfo InvariantCulture      2020-06-29T12 15 22Z    For me NodaTime code looks quite verbose  But types are really useful  They help to handle date time values correctly   Newtonsoft Json     To use NodaTime with Newtonsoft Json you need to add reference to NodaTime Serialization JsonNet NuGet package and configure JSON options    services      AddMvc        AddJsonOptions options   gt                var settings options SerializerSettings          settings DateParseHandling   DateParseHandling None          settings ConfigureForNodaTime DateTimeZoneProviders Tzdb

User · Answer

Note to readers  Several commenters have pointed out some problems in this answer  related particularly to the first suggestion   Refer to the comments section for more information    DateTime UtcNow ToString  yyyy-MM-ddTHH   mm   ss fffffffzzz      This gives you a date similar to 2008-09-22T13 57 31 2311892-04 00   Another way is   DateTime UtcNow ToString  o      which gives you 2008-09-22T14 01 54 9571247Z  To get the specified format  you can use   DateTime UtcNow ToString  yyyy-MM-ddTHH mm ssZ     DateTime Formatting Options

User · Answer

You have a few options including the  quot Round-trip   quot O quot   format specifier quot   var date1   new DateTime 2008  3  1  7  0  0   Console WriteLine date1 ToString  quot O quot     Console WriteLine date1 ToString  quot s quot   System Globalization CultureInfo InvariantCulture     Output 2008-03-01T07 00 00 0000000 2008-03-01T07 00 00  However  DateTime   TimeZone may present other problems as described in the blog post DateTime and DateTimeOffset in  NET  Good practices and common pitfalls   DateTime has countless traps in it that are designed to give your code bugs  1 - DateTime values with DateTimeKind Unspecified are bad news  2 - DateTime doesn t care about UTC Local when doing comparisons  3 - DateTime values are not aware of standard format strings  4 - Parsing a string that has a UTC marker with DateTime does not guarantee a UTC time

User · Answer

It is interesting that custom format  yyyy-MM-ddTHH mm ssK   without ms  is the quickest format method   Also it is interesting that  S  format is slow on Classic and fast on Core     Of course numbers are very close  between some rows difference is insignificant  tests with suffix  Verify are the same as those that are without that suffix  demonstrates results repeatability   BenchmarkDotNet v0 10 5  OS Windows 10 0 14393 Processor Intel Core i5-2500K CPU 3 30GHz  Sandy Bridge   ProcessorCount 4 Frequency 3233539 Hz  Resolution 309 2587 ns  Timer TSC    Host    Clr 4 0 30319 42000  64bit RyuJIT-v4 6 1637 0   Clr      Clr 4 0 30319 42000  64bit RyuJIT-v4 6 1637 0   Core      NET Core 4 6 25009 03  64bit RyuJIT                  Method    Job   Runtime         Mean       Error      StdDev       Median          Min          Max   Rank    Gen 0   Allocated   ---------------------  -----  --------  -----------  ----------  ----------  -----------  -----------  -----------  -----  -------  ----------              CustomDev1    Clr       Clr   1 089 0 ns   22 179 ns   20 746 ns   1 079 9 ns   1 068 9 ns   1 133 2 ns      8   0 1086       424 B              CustomDev2    Clr       Clr   1 032 3 ns   19 897 ns   21 289 ns   1 024 7 ns   1 000 3 ns   1 072 0 ns      7   0 1165       424 B        CustomDev2WithMS    Clr       Clr   1 168 2 ns   16 543 ns   15 474 ns   1 168 5 ns   1 149 3 ns   1 189 2 ns     10   0 1625       592 B                 FormatO    Clr       Clr   1 563 7 ns   31 244 ns   54 721 ns   1 532 5 ns   1 497 8 ns   1 703 5 ns     14   0 2897       976 B                 FormatS    Clr       Clr   1 243 5 ns   24 615 ns   31 130 ns   1 229 3 ns   1 200 6 ns   1 324 2 ns     13   0 2865       984 B          FormatS Verify    Clr       Clr   1 217 6 ns   11 486 ns   10 744 ns   1 216 2 ns   1 205 5 ns   1 244 3 ns     12   0 2885       984 B           CustomFormatK    Clr       Clr     912 2 ns   17 915 ns   18 398 ns     916 6 ns     878 3 ns     934 1 ns      4   0 0629       240 B    CustomFormatK Verify    Clr       Clr     894 0 ns    3 877 ns    3 626 ns     893 8 ns     885 1 ns     900 0 ns      3   0 0636       240 B              CustomDev1   Core      Core     989 1 ns   12 550 ns   11 739 ns     983 8 ns     976 8 ns   1 015 5 ns      6   0 1101       423 B              CustomDev2   Core      Core     964 3 ns   18 826 ns   23 809 ns     954 1 ns     935 5 ns   1 015 6 ns      5   0 1267       423 B        CustomDev2WithMS   Core      Core   1 136 0 ns   21 914 ns   27 714 ns   1 138 1 ns   1 099 9 ns   1 200 2 ns      9   0 1752       590 B                 FormatO   Core      Core   1 201 5 ns   16 262 ns   15 211 ns   1 202 3 ns   1 178 2 ns   1 225 5 ns     11   0 0656       271 B                 FormatS   Core      Core     993 5 ns   19 272 ns   24 372 ns     999 4 ns     954 2 ns   1 029 5 ns      6   0 0633       279 B          FormatS Verify   Core      Core   1 003 1 ns   17 577 ns   16 442 ns   1 009 2 ns     976 1 ns   1 024 3 ns      6   0 0674       279 B           CustomFormatK   Core      Core     878 2 ns   17 017 ns   20 898 ns     877 7 ns     851 4 ns     928 1 ns      2   0 0555       215 B    CustomFormatK Verify   Core      Core     863 6 ns    3 968 ns    3 712 ns     863 0 ns     858 6 ns     870 8 ns      1   0 0550       215 B     Code       public class BenchmarkDateTimeFormat               public static DateTime dateTime   DateTime Now            Benchmark          public string CustomDev1                         var d   dateTime ToUniversalTime                var sb   new StringBuilder 20                sb Append d Year  Append  -                if  d Month  lt   9                  sb Append  0                sb Append d Month  Append  -                if  d Day  lt   9                  sb Append  0                sb Append d Day  Append  T                if  d Hour  lt   9                  sb Append  0                sb Append d Hour  Append                   if  d Minute  lt   9                  sb Append  0                sb Append d Minute  Append                   if  d Second  lt   9                  sb Append  0                sb Append d Second  Append  Z                var text   sb ToString                return text                      Benchmark          public string CustomDev2                         var u   dateTime ToUniversalTime                var sb   new StringBuilder 20               var y   u Year              var d   u Day              var M   u Month              var h   u Hour              var m   u Minute              var s   u Second              sb Append y  Append  -                if  M  lt   9                  sb Append  0                sb Append M  Append  -                if  d  lt   9                  sb Append  0                sb Append d  Append  T                if  h  lt   9                  sb Append  0                sb Append h  Append                   if  m  lt   9                  sb Append  0                sb Append m  Append                   if  s  lt   9                  sb Append  0                sb Append s  Append  Z                var text   sb ToString                return text                      Benchmark          public string CustomDev2WithMS                         var u    dateTime ToUniversalTime                var sb   new StringBuilder 23               var y    u Year              var d    u Day              var M    u Month              var h    u Hour              var m    u Minute              var s    u Second              var ms   u Millisecond              sb Append y  Append  -                if  M  lt   9                  sb Append  0                sb Append M  Append  -                if  d  lt   9                  sb Append  0                sb Append d  Append  T                if  h  lt   9                  sb Append  0                sb Append h  Append                   if  m  lt   9                  sb Append  0                sb Append m  Append                   if  s  lt   9                  sb Append  0                sb Append s  Append                   sb Append ms  Append  Z                var text   sb ToString                return text                     Benchmark          public string FormatO                         var text   dateTime ToUniversalTime   ToString  o                return text                     Benchmark          public string FormatS                         var text   string Concat dateTime ToUniversalTime   ToString  s    Z                return text                      Benchmark          public string FormatS Verify                         var text   string Concat dateTime ToUniversalTime   ToString  s     Z                return text                      Benchmark          public string CustomFormatK                         var text   dateTime ToUniversalTime   ToString  yyyy-MM-ddTHH mm ssK                return text                      Benchmark          public string CustomFormatK Verify                         var text   dateTime ToUniversalTime   ToString  yyyy-MM-ddTHH mm ssK                return text                    https   github com dotnet BenchmarkDotNet was used

User · Answer

DateTime UtcNow ToString  quot s quot   System Globalization CultureInfo InvariantCulture  should give you what you are looking for as the  quot s quot  format specifier is described as a sortable date time pattern  conforms to ISO 8601  EDIT  To get the additional Z at the end as the OP requires  use  quot o quot  instead of  quot s quot

User · Answer

The  s  standard format specifier represents a custom date and time format string that is defined by the DateTimeFormatInfo SortableDateTimePattern property  The pattern reflects a defined standard  ISO 8601   and the property is read-only  Therefore  it is always the same  regardless of the culture used or the format provider supplied  The custom format string is  yyyy - MM - dd T HH   mm   ss        When this standard format specifier is used  the formatting or parsing operation always uses the invariant culture        from MSDN

User · Answer

DateTime Now ToString  yyyy-MM-dd T HH mm ss zzz     DateTime Now ToString  O      NOTE  Depending on the conversion you are doing on your end  you will be using the first line  most like it  or the second one   Make sure to applied format only at local time  since  zzz  is the time zone information for UTC conversion

User · Answer

You can get the  Z   ISO 8601 UTC  with the next code   Dim tmpDate As DateTime   New DateTime Now Ticks  DateTimeKind Utc  Dim res as String   tmpDate toString  o    2009-06-15T13 45 30 0000000Z     Here is why   The ISO 8601 have some different formats   DateTimeKind Local  2009-06-15T13 45 30 0000000-07 00   DateTimeKind Utc  2009-06-15T13 45 30 0000000Z   DateTimeKind Unspecified  2009-06-15T13 45 30 0000000      NET provides us with an enum with those options    2009-06-15T13 45 30 0000000-07 00 Dim strTmp1 As String   New DateTime Now Ticks  DateTimeKind Local  ToString  o     2009-06-15T13 45 30 0000000Z Dim strTmp2 As String   New DateTime Now Ticks  DateTimeKind Utc  ToString  o     2009-06-15T13 45 30 0000000 Dim strTmp3 As String   New DateTime Now Ticks  DateTimeKind Unspecified  ToString  o     Note  If you apply the Visual nbsp Studio nbsp 2008  watch utility  to  the toString  o   part you may get different results  I don t know if it s a bug  but in this case you have better results using a String variable if you re debugging   Source  Standard Date and Time Format Strings  MSDN

User · Answer

Using Newtonsoft Json  you can do  JsonConvert SerializeObject DateTime UtcNow    Example  https   dotnetfiddle net O2xFSl

User · Answer

To format like 2018-06-22T13 04 16 which can be passed in the URI of an API use   public static string FormatDateTime DateTime dateTime        return dateTime ToString  s   System Globalization CultureInfo InvariantCulture

User · Answer

Most of these answers have milliseconds   microseconds which clearly isn t supported by ISO nbsp 8601  The correct answer would be   System DateTime Now ToString  yyyy-MM-ddTHH mm ssK       or System DateTime Now ToUniversalTime   ToString  yyyy-MM-ddTHH mm ssK      References    ISO 8601 specification  K  Specifier

[c#] Given a DateTime object, how do I get an ISO 8601 date in string format?

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