如何使用 TimeZoneInfo 获取夏时制的本地时间？

我正在尝试使用 DateTimeOffset来传达跨越任何时区的特定时刻。我不知道如何使用 ABc1来处理夏时制。

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));

这个打印出来:

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

我在中央时区我们现在在夏时制。 我试着让第二行写道:

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?

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最佳答案

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)));
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You can also use TimeZoneInfo.ConvertTimeFromUtc, which will allow for daylight saving time:

DateTime utc = DateTime.UtcNow;
TimeZoneInfo zone = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
DateTime localDateTime = TimeZoneInfo.ConvertTimeFromUtc(utc, zone);
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Or better, if you don't want to hard code the time zone identifier:

TimeZoneInfo tzi = TimeZoneInfo.FindSystemTimeZoneById(TimeZoneInfo.Local.Id);
DateTime localDateTime = TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, tzi);
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I'm a beginner both at .NET and stackoverflow, so I could be wrong, but here goes:

Using TimeZoneInfo.ConvertTimeFromUtc will allow for daylight saving time, and convert to the correct time according to the time zone + a possible DST offset. However - the offset itself in the resulting object will show the offset for standard time, and not take daylight saving time into account. So if you want to do a ToString on the object, you will end up with the correct time (in hours and minutes), but the wrong offset during daylight saving time, which may lead to the wrong moment in time later in the code.

If you instead use the GetUtcOffset to get the offset for a specific time, and then do a ToOffset on the DateTimeOffset object, both the hours/minutes and the offset itself will be correctly converted, and you can safely do a ToString.

string ExpectedDateTimePattern = "yyyy'-'MM'-'dd'T'HH':'mm':'ss''zzz";
string timeZoneId = "FLE Standard Time";
string dateTimestr = "2017-10-09T09:00:00+02:00";


DateTimeOffset dto = DateTimeOffset.Parse(dateTimeStr);
TimeZoneInfo zone = TimeZoneInfo.FindSystemTimeZoneById(timeZoneId);
TimeSpan offset = zone.GetUtcOffset(dto);
dto = dto.ToOffset(offset);
string localTime = dto.ToString(ExpectedDateTimePattern);

localTime will return "2017-10-09T10:00:00+03:00".

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This will Adjust automatically... and Return time as per your timezone.

public static string SetLastModified (

TimeZoneInfo csttzi = TimeZoneInfo.FindSystemTimeZoneById(TimeZone.CurrentTimeZone.StandardName);

DateTime cstTime = TimeZoneInfo.ConvertTime(DateTime.UtcNow, csttzi);

return String.Format("DaylightSavingTime: {0}", cstTime.IsDaylightSavingTime().ToString());

}


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