Check if daylight savings is in effect?

问题

How to check if in Denmark daylight time savings has taken effect, if so, then add 1 hour to my data, else not? I have a xml file:

<day = "1"
month = "5"
sunrise ="06:30"
sunset ="21:30"
/>

回答1:

Think you need convert this xml to DateTime and then use TimeZoneInfo class.

If Denmark your local time:

DateTime thisTime = DateTime.Now;
bool isDaylight = TimeZoneInfo.Local.IsDaylightSavingTime(thisTime);

Else you need to get Denmark TimeZone:

DateTime thisTime = DateTime.Now;
// get Denmark Standard Time zone - not sure about that
TimeZoneInfo tst = TimeZoneInfo.FindSystemTimeZoneById("Denmark Standard Time");
bool isDaylight = tst.IsDaylightSavingTime(thisTime);

回答2:

When I coded as above - for New-York, I found in the debugger that the time was set correctly (including DST)

TimeZoneInfo nyTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");

DateTime nyTime = GetLocalDateTime(DateTime.UtcNow, nyTimeZone);

if (nyTimeZone.IsDaylightSavingTime(nyTime))
    nyTime = nyTime.AddHours(1);

public static DateTime GetLocalDateTime(DateTime utcDateTime, TimeZoneInfo timeZone)
    {

        utcDateTime = DateTime.SpecifyKind(utcDateTime, DateTimeKind.Utc);

        DateTime time = TimeZoneInfo.ConvertTime(utcDateTime, timeZone);

        return time;

    }

回答3:

You can use TimeZoneInfo.IsDaylightSavingTime

DateTime theDate = new DateTime(2012, 5, 1); // may 1st
TimeZoneInfo tzi = TimeZoneInfo.FindSystemTimeZoneById("Central European Standard Time");
bool isCurrentlyDaylightSavings = tzi.IsDaylightSavingTime(theDate);

回答4:

Here is a generic test and happy to be corrected if my math is incorrect. In my case I just needed to get the GMT offset for the timezone regardless of where it was in the world.

  int timezone;

  TimeZoneInfo localZone = TimeZoneInfo.Local;

  DateTime myTime = DateTime.Now;

  bool isDayLight = TimeZoneInfo.Local.IsDaylightSavingTime(myTime);

  if (isDayLight)
            timezone = Math.Abs(localZone.BaseUtcOffset.Hours) + 1;
  else
            timezone = Math.Abs(localZone.BaseUtcOffset.Hours);

  Debug.WriteLine("timezone is " + timezone);

I simply found the current time and if it was in Day Light Savings period added +1 to the GMT offset.

This works with Visual Studio Express 2013.

回答5:

You need to do two things:

call IsAmbiguous
List item IsDaylightSavingTime.

if (TimeZoneInfo.Local.IsAmbiguousTime(unclearDate) || TimeZoneInfo.Local.IsDaylightSavingTime(unclearDate)) Console.WriteLine("{0} may be daylight saving time in {1}.", unclearDate, TimeZoneInfo.Local.DisplayName);

https://msdn.microsoft.com/en-us/library/bb460642(v=vs.110).aspx

回答6:

this is my short solution which can be using in all timezones:

DateTime utcTime = DateTime.Parse("30.10.2018 18:21:34")
DateTime localtime = ConvertUTCToLocalTime(utcTime);


public static DateTime ConvertUTCToLocalTime(DateTime UTCTime)
{
    var localZone = TimeZone.CurrentTimeZone;
    var offset = localZone.GetUtcOffset(UTCTime);
    var localTime = UTCTime.AddHours(offset.Hours);
    return localTime;
}

回答7:

Important

myDateTime.IsDaylightSavingTime DOES return the proper value... but... it is accurate down to at least the hour of the day, just passing the date alone isn't enough.

For instance this year (2019) 3/10/2019 02:00:00 passed as myDateTime will return false, but 3/10/2019 03:00:00 will return true.

来源：https://stackoverflow.com/questions/10665678/check-if-daylight-savings-is-in-effect

标签

windows-phone-7

datetime

dst