date time convert with hours offset

[jwyman]

Hello all,

I am trying to convert "2024-07-01T11:00:00-08:00" to "858 PM EDT Sun Jun 30 2024".

There is an UTC hour offset (-8:00) which converts to the local time (whatever that is).

I am trying to determine the current time zone string (EDT,CDT,PDT, etc.) from the first string with hour offset.

Need to take into account daylight savings time or not.

Thanks All!

Jim

[dday9]

-08:00 represents the pacific TimeZone. Your DateTimeOffset literal does not equal 858 PM EDT Sun Jun 30 2024 by the way, it equals 3PM July 1 for EST.

What you can do is parse the DateTimeOffset, get the desired TimeZone by the string, then convert the parsed DateTimeOffset using the matched TimeZone:

Private Function ParseDateTimeOffsetToSpecificTimeZone(literal As String, timezone As String) As DateTime
    Dim parsedDateTimeOffset = DateTimeOffset.Parse(literal, Nothing, DateTimeStyles.AssumeUniversal)
    Dim desiredTimeZone = TimeZoneInfo.FindSystemTimeZoneById(timezone)
    Dim conversion = TimeZoneInfo.ConvertTime(parsedDateTimeOffset, desiredTimeZone)
    Return conversion.DateTime
End Function

Fiddle: https://dotnetfiddle.net/cMZ0DH

[jwyman]

-08:00 represents the pacific TimeZone. Your DateTimeOffset literal does not equal 858 PM EDT Sun Jun 30 2024 by the way, it equals 3PM July 1 for EST.

What you can do is parse the DateTimeOffset, get the desired TimeZone by the string, then convert the parsed DateTimeOffset using the matched TimeZone:

Private Function ParseDateTimeOffsetToSpecificTimeZone(literal As String, timezone As String) As DateTime
    Dim parsedDateTimeOffset = DateTimeOffset.Parse(literal, Nothing, DateTimeStyles.AssumeUniversal)
    Dim desiredTimeZone = TimeZoneInfo.FindSystemTimeZoneById(timezone)
    Dim conversion = TimeZoneInfo.ConvertTime(parsedDateTimeOffset, desiredTimeZone)
    Return conversion.DateTime
End Function

Fiddle: https://dotnetfiddle.net/cMZ0DH

Thanks. I just used that example for formatting purposes only. I knew that the times didn't match.

my wish is to get the timezone string (i.e. PDT) from the hour offset. And it needs to automatically account for savings time.

[.paul.]

https://learn.microsoft.com/en-us/do...e?view=net-8.0

If daylight saving is in force, it’ll be automatically applied

[.paul.]

https://learn.microsoft.com/en-us/do...e?view=net-8.0

[dday9]

My wish is to get the timezone string (i.e. PDT) from the hour offset.

You will need to get the Offset from the parsed DateTimeOffset value then loop over the TimeZones checking which offset matches:

Private Function GetTimeZoneStringFromOffset(literal As String) As String
    Dim parsedDateTimeOffset = DateTimeOffset.Parse(literal, Nothing, DateTimeStyles.AssumeUniversal)
    Dim offset = parsedDateTimeOffset.Offset
    Dim timeZones = TimeZoneInfo.GetSystemTimeZones()

    For Each timeZone In timeZones
        If (timeZone.BaseUtcOffset = offset) Then
            Return timeZone.Id
        End If
    Next

    Return Nothing
End Function

Fiddle: https://dotnetfiddle.net/hauxnP

[jwyman]

You will need to get the Offset from the parsed DateTimeOffset value then loop over the TimeZones checking which offset matches:

Private Function GetTimeZoneStringFromOffset(literal As String) As String
    Dim parsedDateTimeOffset = DateTimeOffset.Parse(literal, Nothing, DateTimeStyles.AssumeUniversal)
    Dim offset = parsedDateTimeOffset.Offset
    Dim timeZones = TimeZoneInfo.GetSystemTimeZones()

    For Each timeZone In timeZones
        If (timeZone.BaseUtcOffset = offset) Then
            Return timeZone.Id
        End If
    Next

    Return Nothing
End Function

Fiddle: https://dotnetfiddle.net/hauxnP

what is the literal format for the input of this function? a date time string or a numeric offset value?

[.paul.]

A numeric offset value converted to a string

[dday9]

Just like what you posted in your original post: 2024-07-01T11:00:00-08:00