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Determine Time Offset from New York

Hi,

I have an application that is distributed all over the world and therefore is run in a wide variety of time zones. I need a way to determine the difference in time (in hours) from where the application is run and New York.

For example, if the application is run in Vancouver Canada (which is -3hrs from NY) then I need a way to determine that difference so I can correctly display New York time from within the application.

Dave Baldwin

Found this in another question: http://www.codeproject.com/KB/vb/TimeZoneInfo.aspx It's meant for changing time zones but it seems to collect all the relevant info first including daylight savings time.

Erick37

Here is some code tio convert from your local time zone to Eastern Time.
To test, change the timezone on your computer to Pacific Time or any other zone and run.

string localZoneId = "Eastern Standard Time";
			TimeZoneInfo tzi = TimeZoneInfo.FindSystemTimeZoneById(localZoneId);

			DateTime localTime = DateTime.UtcNow;

			Console.WriteLine(string.Format("Local Time: {0}",DateTime.Now.ToLongTimeString()));
			
			DateTime easternTime = TimeZoneInfo.ConvertTime(localTime, TimeZoneInfo.Utc, tzi);

			Console.WriteLine(string.Format("Eastern Time: {0}",easternTime.ToLongTimeString()));

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Erick37

And the VB version:

Dim localZoneId As String = "Eastern Standard Time"
		Dim tzi As TimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById(localZoneId)

		Dim localTime As DateTime = DateTime.UtcNow

		Console.WriteLine(String.Format("Local Time: {0}", DateTime.Now.ToLongTimeString()))

		Dim easternTime As DateTime = TimeZoneInfo.ConvertTime(localTime, TimeZoneInfo.Utc, tzi)

		Console.WriteLine(String.Format("Eastern Time: {0}", easternTime.ToLongTimeString()))

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ASKER CERTIFIED SOLUTION

Ark

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RobertFromSecretWeapons

ASKER

Hi,
All three answers were quite good, but Ark addressed my question specifically.
Thx.

Ark

Thanks for points, Glad I could help.
More correct version below. In my short sample above there can be problem with daylight saving time - in the day of time switching GetUtcOffset parameter should refer to localTime (local for machine and NY_Time). For example? if tiime changes at 03 AM in NY and Vancouver time is 01 AM Utc offset will differ.

Dim Local_Offset As Double = System.TimeZoneInfo.Local.GetUtcOffset(Date.Now).TotalHours
Dim Dim tzi_NY As TimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time").
Dim NY_Time As DateTime = TimeZoneInfo.ConvertTime(DateTime.UtcNow, TimeZoneInfo.Utc, tzi_NY)
Dim NY_Offset As Double = tzi_NY.GetUtcOffset(NY_Tyme).TotalHours
Dim delta As Double = Local_Offset - NY_Offset

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RobertFromSecretWeapons

ASKER

Thx Ark, I would not have known that unless you provided this.

RobertFromSecretWeapons

ASKER

Ark, Can you give a second look to what you just provided, you have a couple of typos in it (beginning and end of line 2). Pls clarify..

Ark

Sorry, I wrote above code directly here, didn't check it in IDE.
Correct version:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Local_Offset As Double = System.TimeZoneInfo.Local.GetUtcOffset(Date.Now).TotalHours
        Dim tzi_NY As TimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time")
        Dim NY_Time As DateTime = TimeZoneInfo.ConvertTime(DateTime.UtcNow, TimeZoneInfo.Utc, tzi_NY)
        Dim NY_Offset As Double = tzi_NY.GetUtcOffset(NY_Time).TotalHours
        Dim delta As Double = Local_Offset - NY_Offset
        MsgBox(delta)
    End Sub

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Ark

A bit better formatted:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Local_Offset As Double = System.TimeZoneInfo.Local.GetUtcOffset(Date.Now).TotalHours
        Dim tzi_NY As TimeZoneInfo = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time")
        Dim NY_Time As DateTime = TimeZoneInfo.ConvertTime(DateTime.UtcNow, TimeZoneInfo.Utc, tzi_NY)
        Dim NY_Offset As Double = tzi_NY.GetUtcOffset(NY_Time).TotalHours
        Dim delta As Double = Local_Offset - NY_Offset

        Dim sFormat As String = "UTC {0};" & vbCrLf
        sFormat += "Local time: {1};" & vbCrLf
        sFormat += "NY_Time: {2};" & vbCrLf
        sFormat += "Local offset: {3};" & vbCrLf
        sFormat += "NY_Offset: {4}; " & vbCrLf
        sFormat += "delta: {5}" & vbCrLf
        MsgBox(String.Format(sFormat, DateTime.UtcNow, DateTime.Now, NY_Time, Local_Offset, NY_Offset, delta))
    End Sub

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RobertFromSecretWeapons

ASKER

Thx for the clarification. It was the dot on the end of the second line that made me wonder...