CODEWITHSUNDEEP
c#timezonedst
Niner
Niner

Reputation: 2205

how to tell DST if server on UTC

My Windows web application server is set at UTC so there is no indication of DST or not on the timezone selection UI. So when my c# code is running on that server, DateTime.Now.IsDaylightSavingTime() always returns False. Is there a way to check to see if a particular time zone (i.e. Eastern Time) is currently in DST or not?

thanks.

Upvotes: 0

Views: 388

Answers (2)

Matt Johnson-Pint
Matt Johnson-Pint

Reputation: 241959

DateTime.Now is evil, and should never be used in server-side code. Read more in my blog post on this subject: The Case Against DateTime.Now. With careful coding, your code should not care what the time zone setting of the server is.

You are looking for this:

TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
bool dst = tz.IsDaylightSavingTime(DateTime.UtcNow);

Don't let the string "Eastern Standard Time" fool you - that is the TimeZoneInfo.Id for the US Eastern time zone, encompassing both Eastern Standard Time and Eastern Daylight Time.

Upvotes: 2

TheEvilPenguin
TheEvilPenguin

Reputation: 5692

You can get a list of all time zones with TimeZoneInfo.GetSystemTimeZones(). It returns a collection of type TimeZoneInfo. When you find the right one, it has a property SupportsDaylightSavingTime to tell you if it uses DST at all.

After that, you can call IsDaylightSavingTime(DateTime) to see if DST is in effect for a given date.

Upvotes: 1

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