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c#datetimeoffsettimezone

How to use TimeZoneInfo to get local time during Daylight Saving Time?

I'm trying to use DateTimeOffset to convey a specific moment in time across any time zone. I can't figure out how to use TimeZoneInfo to deal with daylight saving time.

var dt = DateTime.UtcNow;
Console.WriteLine(dt.ToLocalTime());

var tz = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
var utcOffset = new DateTimeOffset(dt, TimeSpan.Zero);
Console.WriteLine(utcOffset.ToOffset(tz.BaseUtcOffset));

This prints out:

6/2/2010 4:37:19 PM
6/2/2010 3:37:19 PM -06:00

I am in the central time zone, and and we are currently in daylight saving time. I am trying to get the second line to read:

6/2/2010 4:37:19 PM -05:00

BaseUtcOffset apparently doesn't change based on DST.

How can I get the the right time with the proper offset value?

Solution

  • You need to get the UtcOffset from the TimeZoneInfo, then pass that to the ToOffset() method:

    var dt = DateTime.UtcNow;
Console.WriteLine(dt.ToLocalTime());

var tz = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
var utcOffset = new DateTimeOffset(dt, TimeSpan.Zero);
Console.WriteLine(utcOffset.ToOffset(tz.GetUtcOffset(utcOffset)));