As described in the timezone tag wiki, there are two different styles of time zones.
Those provided by Microsoft for use with Windows and the .Net TimeZoneInfo class (when running on Windows) are identified by a value such as "Eastern Standard Time".
Those provided by IANA in the TZDB, and used by the .NET TimeZoneInfo class when running on Linux or OSX, are identified by a value such as "America/New_York".
Many Internet-based APIs use the IANA time zones, but for numerous reasons one might need to convert this to a Windows time zone id, or vice-versa.
How can this be accomplished in .Net?
Current Status:
Starting with .NET 6, both forms of time zones are supported on any platform that has both time zone data and ICU installed, which is most installations of Windows, Linux, and MacOS. See Tobias's answer.
Original Answer:
The primary source of the data for conversion between Windows and IANA time zone identifiers is the windowsZones.xml file, distributed as part of the Unicode CLDR project. The latest dev version can be found here.
However, CLDR is released only twice annually. This, along with the periodic cadence of Windows updates, and the irregular updates of the IANA time zone database, makes it complicated to just use the CLDR data directly. Keep in mind that time zone changes themselves are made at the whim of the world's various governments, and not all changes are made with sufficient notice to make it into these release cycles before their respective effective dates.
There are a few other edge cases that need to be handled that are not covered strictly by the CLDR, and new ones pop up from time to time. Therefore, I've encapsulated the complexity of the solution into the TimeZoneConverter micro-library, which can be installed from Nuget.
Using this library is simple. Here are some examples of conversion:
string tz = TZConvert.IanaToWindows("America/New_York");
// Result: "Eastern Standard Time"
string tz = TZConvert.WindowsToIana("Eastern Standard Time");
// result: "America/New_York"
string tz = TZConvert.WindowsToIana("Eastern Standard Time", "CA");
// result: "America/Toronto"
There are more examples on the project site.
It's important to recognize that while an IANA time zone can be mapped to a single Windows time zone, the reverse is not true. A single Windows time zone might be mapped to more than one IANA time zone. This can be seen in the above examples, where Eastern Standard Time is mapped to both America/New_York, and to America/Toronto. TimeZoneConverter will deliver the one that CLDR marks with "001", known as the "golden zone", unless you specifically provide a country code and there's a match for a different zone in that country.
Note: This answer has evolved over the years, so comments below may or may not apply to the current revision. Review the edit history for details. Thanks.
Starting with .NET 6, it is finally possible to work with time zones in a cross-platform manner, so these manual workarounds are no longer needed.
The TimeZoneInfo.FindSystemTimeZoneById(string) method automatically accepts either Windows or IANA time zones on either platform and converts them if needed.
// Both of these will now work on any supported OS where ICU and time zone data are available.
TimeZoneInfo tzi1 = TimeZoneInfo.FindSystemTimeZoneById("AUS Eastern Standard Time");
TimeZoneInfo tzi2 = TimeZoneInfo.FindSystemTimeZoneById("Australia/Sydney");
Note that, as specified on the link, the .NET Core Alpine Linux-based Docker images do not have the necessary tzdata installed by default, so it must be installed in your Dockerfile for this to work correctly.
I know this is an old question, but I had a use case I though I would share here, since this is the most relevant post I found when searching. I was developing a .NET Core app using a docker linux container, but for deployment on a windows server. So I only needed my docker linux container to support the windows timezone names. I got this working without changing my application code by doing the following:
cp /usr/share/zoneinfo/America/Chicago "/usr/share/zoneinfo/Central Standard Time"
cp /usr/share/zoneinfo/America/New_York "/usr/share/zoneinfo/Eastern Standard Time"
cp /usr/share/zoneinfo/America/Denver "/usr/share/zoneinfo/Mountain Standard Time"
cp /usr/share/zoneinfo/America/Los_Angeles "/usr/share/zoneinfo/Pacific Standard Time"
Then, in my .NET code, the following worked without any modification: TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time")
Related
I am using below code to get time zone details for "Gulf Standard Time", but its throwing error as below
The time zone ID 'Gulf Standard Time' was not found on the local computer.
below is line of code i am using
TimeZoneInfo tZone = TimeZoneInfo.FindSystemTimeZoneById("Gulf Standard Time");
Can you please tell me what exactly is the issue in code, as i have checked and its correct time zone name.
As pointed out in comments, "Gulf Standard Time" isn't a valid Windows time zone identifier.
Gulf Standard Time usually refers to UTC+04:00 with no DST, as observed in the United Arab Emirates and Oman, as described here. The corresponding time zone in Windows appears with an English display name of (UTC+04:00) Abu Dhabi, Muscat, and has a corresponding ID of Arabian Standard Time.
Thus in .NET:
TimeZoneInfo tZone = TimeZoneInfo.FindSystemTimeZoneById("Arabian Standard Time");
Console.WriteLine(tzone.DisplayName);
// prints: (UTC+04:00) Abu Dhabi, Muscat
To get a list of supported time zones, use TimeZoneInfo.GetSystemTimeZones() in your .NET code, and examine the Id and DisplayName properties. Alternatively, you can call TZUTIL /L on the command line to list them.
Also, just to point out that this all assumes you are running on Windows. If you are actually running .NET Core on non-Windows systems (Linux, OSX, etc.), then you should uses IANA time zone IDs. In this case, either "Asia/Dubai", or "Asia/Muscat" would be appropriate.
And if your code might run both on Windows and Non-Windows systems, then you will need to take advantage of my TimeZoneConverter library.
My Xamarin form for iOS and android is heavily use the device time and require to setup using different time in other countries.
I do a search and found this to list all the timezone available:
foreach (TimeZoneInfo z in TimeZoneInfo.GetSystemTimeZones())
Console.WriteLine(z.Id);
In my scenario, user can choose any of the sites and set the correct timezone based on where their sites are so the time will be shown relative to their chosen site.
I ran the code and least all the timezone available. Looks like the iOS and android have different presentation of the Timezone Id. I assumed is because of the different system.
I am just worry that the timezone id not fully listed coz our application runs internationally, actually most application run internationally.
var utcTime = DateTime.UtcNow;
var zone = TimeZoneInfo.FindSystemTimeZoneById("Hongkong");
var zoneTime = TimeZoneInfo.ConvertTimeFromUtc(utcTime, zone);
System.Diagnostics.Debug.WriteLine("Device Timezone : " + DateTime.Now + " " + TimeZone.CurrentTimeZone.StandardName);
System.Diagnostics.Debug.WriteLine("Hong Kong Time : " + zoneTime.ToString("G"));
Another note: Will the above code taking care of the day light saving as well? e.g. In NZ, each year NZ have to move time forward or background by an hour where other countries are not.
TimeZoneInfo.GetSystemTimeZones() does exactly what it says - gets the time zones available on the system it is running on. In general, one cannot assume that all systems will have the same time zones installed.
It's a little safer to assume that if all systems are Windows desktop computers, but even then it will depend on whether those computers are kept updated with the latest time zones changes (delivered through Windows Update and OS builds in Windows 10).
In a cross-platform world, all bets are off. You might get Windows time zone IDs. You might get IANA time zone IDs. You might get something else.
You showed an example of "Hongkong". That is indeed a valid alias to "Asia/Hong_Kong" in the IANA time zone database. So probably your environment is giving IANA IDs. (You should prefer "Asia/Hong_Kong" though.)
If you think you might need to convert between IANA and Windows time zones, you can use my TimeZoneConverter library. However, in your case it seems like it would be much safer to use Noda Time, as it will bundle the time zone data with your application, rather than relying on the operating system to provide the data.
Yes, that code does correctly handle daylight saving time. For New Zealand, you'd use "Pacific/Auckland" for the IANA time zone ID. However, you should choose either TimeZoneInfo.Local.StandardName or TimeZoneInfo.DaylightName depending on TimeZoneInfo.IsDaylightSavingTime result. Or, if you want more accurate and localized names, you can use my TimeZoneNames library.
C# supports different timezone id's across the globe. Please find list of time zones that are being supported by C# in below link:
https://msdn.microsoft.com/en-us/library/gg154758.aspx
The timezone id's are used in C# library functions to convert times across the timezones.
[e.g. TimeZoneInfo.ConvertTimeBySystemTimeZoneId("Hawaiian Standard Time")]
Similarly I want support for AMERICA/MIQUELON, which is not present in the msdn list provided in above link.
Can somebody please provide workaround for this specific timezone?
Time zone identifiers like "America/Miquelon" and the others you listed (before editing your question) are from the IANA time zone database. You can read more in the timezone tag wiki and on Wikipedia.
Note that they are usually presented in mixed case form, rather than in all capital letters.
The easiest and best way to work with these in .NET is via the Noda Time library.
For example:
DateTimeZone tz = DateTimeZoneProviders.Tzdb["America/Miquelon"];
Instant now = SystemClock.Instance.Now;
ZonedDateTime converted = now.InZone(tz);
As described in the timezone tag wiki, there are two different styles of time zones.
Those provided by Microsoft for use with Windows and the .Net TimeZoneInfo class (when running on Windows) are identified by a value such as "Eastern Standard Time".
Those provided by IANA in the TZDB, and used by the .NET TimeZoneInfo class when running on Linux or OSX, are identified by a value such as "America/New_York".
Many Internet-based APIs use the IANA time zones, but for numerous reasons one might need to convert this to a Windows time zone id, or vice-versa.
How can this be accomplished in .Net?
Current Status:
Starting with .NET 6, both forms of time zones are supported on any platform that has both time zone data and ICU installed, which is most installations of Windows, Linux, and MacOS. See Tobias's answer.
Original Answer:
The primary source of the data for conversion between Windows and IANA time zone identifiers is the windowsZones.xml file, distributed as part of the Unicode CLDR project. The latest dev version can be found here.
However, CLDR is released only twice annually. This, along with the periodic cadence of Windows updates, and the irregular updates of the IANA time zone database, makes it complicated to just use the CLDR data directly. Keep in mind that time zone changes themselves are made at the whim of the world's various governments, and not all changes are made with sufficient notice to make it into these release cycles before their respective effective dates.
There are a few other edge cases that need to be handled that are not covered strictly by the CLDR, and new ones pop up from time to time. Therefore, I've encapsulated the complexity of the solution into the TimeZoneConverter micro-library, which can be installed from Nuget.
Using this library is simple. Here are some examples of conversion:
string tz = TZConvert.IanaToWindows("America/New_York");
// Result: "Eastern Standard Time"
string tz = TZConvert.WindowsToIana("Eastern Standard Time");
// result: "America/New_York"
string tz = TZConvert.WindowsToIana("Eastern Standard Time", "CA");
// result: "America/Toronto"
There are more examples on the project site.
It's important to recognize that while an IANA time zone can be mapped to a single Windows time zone, the reverse is not true. A single Windows time zone might be mapped to more than one IANA time zone. This can be seen in the above examples, where Eastern Standard Time is mapped to both America/New_York, and to America/Toronto. TimeZoneConverter will deliver the one that CLDR marks with "001", known as the "golden zone", unless you specifically provide a country code and there's a match for a different zone in that country.
Note: This answer has evolved over the years, so comments below may or may not apply to the current revision. Review the edit history for details. Thanks.
Starting with .NET 6, it is finally possible to work with time zones in a cross-platform manner, so these manual workarounds are no longer needed.
The TimeZoneInfo.FindSystemTimeZoneById(string) method automatically accepts either Windows or IANA time zones on either platform and converts them if needed.
// Both of these will now work on any supported OS where ICU and time zone data are available.
TimeZoneInfo tzi1 = TimeZoneInfo.FindSystemTimeZoneById("AUS Eastern Standard Time");
TimeZoneInfo tzi2 = TimeZoneInfo.FindSystemTimeZoneById("Australia/Sydney");
Note that, as specified on the link, the .NET Core Alpine Linux-based Docker images do not have the necessary tzdata installed by default, so it must be installed in your Dockerfile for this to work correctly.
I know this is an old question, but I had a use case I though I would share here, since this is the most relevant post I found when searching. I was developing a .NET Core app using a docker linux container, but for deployment on a windows server. So I only needed my docker linux container to support the windows timezone names. I got this working without changing my application code by doing the following:
cp /usr/share/zoneinfo/America/Chicago "/usr/share/zoneinfo/Central Standard Time"
cp /usr/share/zoneinfo/America/New_York "/usr/share/zoneinfo/Eastern Standard Time"
cp /usr/share/zoneinfo/America/Denver "/usr/share/zoneinfo/Mountain Standard Time"
cp /usr/share/zoneinfo/America/Los_Angeles "/usr/share/zoneinfo/Pacific Standard Time"
Then, in my .NET code, the following worked without any modification: TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time")
I have a system which consists of a C# back end and a Java front end. The C# back end communicates with other systems and some mobile devices.
On the C# side, my task is among others to recognize the time zone of the timestamps coming from the mobile devices and create the corresponding TimeZoneInfo object. This is working without any problems.
On the Java side, I have to display the time zone information together with the data sent by a mobile device. I'm using the TimeZone class to store the time zone information within my domain objects.
Now the question is how can I create a Java's TimeZone object which corresponds with a C#'s TimeZoneInfo object? AFAIK the time zones do not have any unique IDs. Further on, the names are also different (e.g. in C#: "Central Europe Standard Time", in Java "Central Europe Time"). Not even the number of the time zones in C# and in Java is equal!
You know that "time" is independent of "time zone", so I won't belabor that point :)
"TimeZone" is really more a function of your OS than a programming language.
Android "Time Zone IDs" correspond to the standard, IANA "Olson database":
http://developer.android.com/reference/java/util/TimeZone.html#getTimeZone%28java.lang.String%29
http://en.wikipedia.org/wiki/Tz_database
The other half of the equation is mapping .Net timezones to the "standard". This link should help:
.NET TimeZoneInfo from Olson time zone
As paulsm4 says, you can map Windows names to TZDB (aka Olson, aka tz, aka zoneinfo) names - although the mapping changes periodically, and you should really look at Unicode CLDR for more details. You should be aware that the format of the mapping table has changed over time, and that some Windows IDs map to multiple TZDB IDs. (Some are missing entirely.)
As an alternative, you could consider abandoning Windows time zone IDs entirely, and use TZDB throughout the stack, if you use Noda Time, a .NET date/time API I've been working on for a while now. You'll also find your Java date/time work easier if you use Joda Time, which is the library I based the "engine" of Noda Time on. It's much nicer than using Date and Calendar in Java.