Does an alternative to [DateTime]::Parse() exist that supports negative years?

[RokeJulianLockhart]

ISO 8601-1:2019+A1:2022 specifies that dates can explicitly positive or negative, like +2024 or -0325, as Wikipedia explains:

1. ISO 8601 prescribes, as a minimum, a four-digit year [YYYY] to avoid the year 2000 problem. It therefore represents years from 0000 to 9999, year 0000 being equal to 1 BC and all others AD, similar to astronomical year numbering.

2. To represent years before 0000 or after 9999, the standard also permits the expansion of the year representation but only by prior agreement between the sender and the receiver.[21] An expanded year representation [±YYYYY] must have an agreed-upon number of extra year digits beyond the four-digit minimum, and it must be prefixed with a + or − sign[22] instead of the more common AD/BC (or CE/BCE) notation; by convention 1 BC is labelled +0000, 2 BC is labeled −0001, and so on.[23]

However, I've tried [DateTime]::Parse() (via PowerShell, hence the format), and it doesn't appear to support this:

1. 1. 1. #!/usr/bin/env -S pwsh
         [DateTime]::Parse('2024-05')

      2. <Objs Version="1.1.0.1" xmlns="http://schemas.microsoft.com/powershell/2004/04">
           <DT>2024-05-01T00:00:00</DT>
         </Objs>

   2. 1. #!/usr/bin/env -S pwsh
         $?

      2. <Objs Version="1.1.0.1" xmlns="http://schemas.microsoft.com/powershell/2004/04">
           <B>true</B>
         </Objs>

2. 1. #!/usr/bin/env -S pwsh
      [DateTime]::Parse('+2024-05')
      Get-Error -Newest 1

   2. <Objs Version="1.1.0.1" xmlns="http://schemas.microsoft.com/powershell/2004/04">
        <Obj RefId="0">
          <TN RefId="0">
            <T>System.Management.Automation.ErrorRecord#PSExtendedError</T>
            <T>System.Object</T>
          </TN>
          <ToString>Exception calling "Parse" with "1" argument(s): "String '+2024-05' was not recognized as a valid DateTime."</ToString>
          <MS>
            <Obj N="Exception" RefId="1">
              <TN RefId="1">
                <T>System.Management.Automation.MethodInvocationException</T>
                <T>System.Management.Automation.MethodException</T>
                <T>System.Management.Automation.ExtendedTypeSystemException</T>
                <T>System.Management.Automation.RuntimeException</T>
                <T>System.SystemException</T>
                <T>System.Exception</T>
                <T>System.Object</T>
              </TN>
              <ToString>System.Management.Automation.MethodInvocationException: Exception calling "Parse" with "1" argument(s): "String '+2024-05' was not recognized as a valid DateTime."_x000A_ ---&gt; System.FormatException: String '+2024-05' was not recognized as a valid DateTime._x000A_   at CallSite.Target(Closure, CallSite, Type, String)_x000A_   --- End of inner exception stack trace ---_x000A_   at System.Management.Automation.ExceptionHandlingOps.ConvertToMethodInvocationException(Exception exception, Type typeToThrow, String methodName, Int32 numArgs, MemberInfo memberInfo)_x000A_   at CallSite.Target(Closure, CallSite, Type, String)_x000A_   at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1)_x000A_   at System.Management.Automation.Interpreter.DynamicInstruction`3.Run(InterpretedFrame frame)_x000A_   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)</ToString>
              <Props>
                <S N="ErrorRecord">Exception calling "Parse" with "1" argument(s): "String '+2024-05' was not recognized as a valid DateTime."</S>
                <B N="WasThrownFromThrowStatement">false</B>
                <S N="TargetSite">Void ConvertToMethodInvocationException(System.Exception, System.Type, System.String, Int32, System.Reflection.MemberInfo)</S>
                <S N="Message">Exception calling "Parse" with "1" argument(s): "String '+2024-05' was not recognized as a valid DateTime."</S>
                <Obj N="Data" RefId="2">
                  <TN RefId="2">
                    <T>System.Collections.ListDictionaryInternal</T>
                    <T>System.Object</T>
                  </TN>
                  <DCT>
                    <En>
                      <S N="Key">System.Management.Automation.Interpreter.InterpretedFrameInfo</S>
                      <Obj N="Value" RefId="3">
                        <TN RefId="3">
                          <T>System.Management.Automation.Interpreter.InterpretedFrameInfo[]</T>
                          <T>System.Array</T>
                          <T>System.Object</T>
                        </TN>
                        <LST>
                          <S>&lt;ScriptBlock&gt;</S>
                        </LST>
                      </Obj>
                    </En>
                  </DCT>
                </Obj>
                <Obj N="InnerException" RefId="4">
                  <TN RefId="4">
                    <T>System.FormatException</T>
                    <T>System.SystemException</T>
                    <T>System.Exception</T>
                    <T>System.Object</T>
                  </TN>
                  <ToString>System.FormatException: String '+2024-05' was not recognized as a valid DateTime._x000A_   at CallSite.Target(Closure, CallSite, Type, String)</ToString>
                  <Props>
                    <S N="TargetSite">System.Object CallSite.Target(System.Runtime.CompilerServices.Closure, System.Runtime.CompilerServices.CallSite, System.Type, System.String)</S>
                    <S N="Message">String '+2024-05' was not recognized as a valid DateTime.</S>
                    <Obj N="Data" RefId="5">
                      <TNRef RefId="2" />
                      <DCT />
                    </Obj>
                    <Nil N="InnerException" />
                    <Nil N="HelpLink" />
                    <S N="Source">Anonymously Hosted DynamicMethods Assembly</S>
                    <I32 N="HResult">-2146233033</I32>
                    <S N="StackTrace">   at CallSite.Target(Closure, CallSite, Type, String)</S>
                  </Props>
                </Obj>
                <Nil N="HelpLink" />
                <S N="Source">System.Management.Automation</S>
                <I32 N="HResult">-2146233087</I32>
                <S N="StackTrace">   at System.Management.Automation.ExceptionHandlingOps.ConvertToMethodInvocationException(Exception exception, Type typeToThrow, String methodName, Int32 numArgs, MemberInfo memberInfo)_x000A_   at CallSite.Target(Closure, CallSite, Type, String)_x000A_   at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1)_x000A_   at System.Management.Automation.Interpreter.DynamicInstruction`3.Run(InterpretedFrame frame)_x000A_   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)</S>
              </Props>
            </Obj>
            <Nil N="TargetObject" />
            <S N="FullyQualifiedErrorId">FormatException</S>
            <Obj N="InvocationInfo" RefId="6">
              <TN RefId="5">
                <T>System.Management.Automation.InvocationInfo</T>
                <T>System.Object</T>
              </TN>
              <ToString>System.Management.Automation.InvocationInfo</ToString>
              <Props>
                <Nil N="MyCommand" />
                <Obj N="BoundParameters" RefId="7">
                  <TN RefId="6">
                    <T>System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Object, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]</T>
                    <T>System.Object</T>
                  </TN>
                  <DCT />
                </Obj>
                <Obj N="UnboundArguments" RefId="8">
                  <TN RefId="7">
                    <T>System.Collections.Generic.List`1[[System.Object, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]</T>
                    <T>System.Object</T>
                  </TN>
                  <LST />
                </Obj>
                <I32 N="ScriptLineNumber">1</I32>
                <I32 N="OffsetInLine">1</I32>
                <I64 N="HistoryId">13</I64>
                <S N="ScriptName"></S>
                <S N="Line">[DateTime]::Parse('+2024-05')</S>
                <S N="Statement">[DateTime]::Parse('+2024-05')</S>
                <S N="PositionMessage">At line:1 char:1_x000A_+ [DateTime]::Parse('+2024-05')_x000A_+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</S>
                <S N="PSScriptRoot"></S>
                <Nil N="PSCommandPath" />
                <S N="InvocationName"></S>
                <I32 N="PipelineLength">0</I32>
                <I32 N="PipelinePosition">0</I32>
                <B N="ExpectingInput">false</B>
                <Obj N="CommandOrigin" RefId="9">
                  <TN RefId="8">
                    <T>System.Management.Automation.CommandOrigin</T>
                    <T>System.Enum</T>
                    <T>System.ValueType</T>
                    <T>System.Object</T>
                  </TN>
                  <ToString>Internal</ToString>
                  <I32>1</I32>
                </Obj>
                <Nil N="DisplayScriptPosition" />
              </Props>
            </Obj>
            <I32 N="ErrorCategory_Category">0</I32>
            <S N="ErrorCategory_Activity"></S>
            <S N="ErrorCategory_Reason">MethodInvocationException</S>
            <S N="ErrorCategory_TargetName"></S>
            <S N="ErrorCategory_TargetType"></S>
            <S N="ErrorCategory_Message">NotSpecified: (:) [], MethodInvocationException</S>
            <B N="SerializeExtendedInfo">false</B>
            <S N="ErrorDetails_ScriptStackTrace">at &lt;ScriptBlock&gt;, &lt;No file&gt;: line 1</S>
          </MS>
        </Obj>
      </Objs>

Does an alternative method exist which does?

[huoyaoyuan]

DateTime in .NET is represented by unsigned tick count from 0001/01/01. It doesn't follow any standard fully.

[RokeJulianLockhart]

#109687 (comment)

@huoyaoyuan, irrespective of its support for any particular standard, does it support negative years in dates? I hope I'm merely passing the datetime incorrectly (for it).

[huoyaoyuan]

does it support negative years in dates?

No. It interprets the tick as unsigned number, and most methods are rejecting dates out of the years 0001-9999.

[Clockwork-Muse]

If you need better date/time support generally in C#, including for a larger range of years, the usual recommendation is to use NodaTime.

[RokeJulianLockhart]

#109687 (reply in thread)

Thanks, @Clockwork-Muse. I'll re-ask this question about AYN support at https://groups.google.com/g/noda-time (and tack on RFC 9557 support), since its README.md seems to recommend that - there's certainly no discussions tab.

[RokeJulianLockhart]

#109687 (reply in thread)

Actually, it has nodatime/nodatime#1799 (comment) open, so I'll be surprised if it doesn't support at least AYN. @Clockwork-Muse, thanks for the recommendation! If it works, I'll mark your comment as the answer.

[RokeJulianLockhart]

#109687 (reply in thread)

@RokeJulianLockhart, it appears not, per https://groups.google.com/g/noda-time/c/gVgsLmnr0iA/m/d5A_wdYcAwAJ. I've filed nodatime/nodatime#1834 (comment).