class NodaTime.​DateTimeZone

<para> The mapping is unambiguous in the "UTC to local" direction, but the reverse is not true: when the offset changes, usually due to a Daylight Saving transition, the change either creates a gap (a period of local time which never occurs in the time zone) or an ambiguity (a period of local time which occurs twice in the time zone). Mapping back from local time to an instant requires consideration of how these problematic times will be handled. </para> <para> Noda Time provides various options when mapping local time to a specific instant: <list type="bullet"><item><description><see cref="M:NodaTime.DateTimeZone.AtStrictly(NodaTime.LocalDateTime)" /> will throw an exception if the mapping from local time is either ambiguous or impossible, i.e. if there is anything other than one instant which maps to the given local time.</description></item><item><description><see cref="M:NodaTime.DateTimeZone.AtLeniently(NodaTime.LocalDateTime)" /> will never throw an exception due to ambiguous or skipped times, resolving to the earlier option of ambiguous matches, or to a value that's forward-shifted by the duration of the gap for skipped times.</description></item><item><description><see cref="M:NodaTime.DateTimeZone.ResolveLocal(NodaTime.LocalDateTime,NodaTime.TimeZones.ZoneLocalMappingResolver)" /> will apply a <see cref="T:NodaTime.TimeZones.ZoneLocalMappingResolver" /> to the result of a mapping.</description></item><item><description><see cref="M:NodaTime.DateTimeZone.MapLocal(NodaTime.LocalDateTime)" /> will return a <see cref="T:NodaTime.TimeZones.ZoneLocalMapping" /> with complete information about whether the given local time occurs zero times, once or twice. This is the most fine-grained approach, which is the fiddliest to use but puts the caller in the most control.</description></item></list></para> <para> Noda Time has two built-in sources of time zone data available: a copy of the <a href="https://www.iana.org/time-zones">tz database</a> (also known as the IANA Time Zone database, or zoneinfo or Olson database), and the ability to convert .NET's own <see cref="T:System.TimeZoneInfo" /> format into a "native" Noda Time zone. Which of these is most appropriate for you to use will very much depend on your exact needs. The zoneinfo database is widely used outside Windows, and has more historical data than the Windows-provided information, but if you need to interoperate with other Windows systems by specifying time zone IDs, you may wish to stick to the Windows time zones. </para> <para> To obtain a <see cref="T:NodaTime.DateTimeZone" /> for a given timezone ID, use one of the methods on <see cref="T:NodaTime.IDateTimeZoneProvider" /> (and see <see cref="T:NodaTime.DateTimeZoneProviders" /> for access to the built-in providers). The UTC timezone is also available via the <see cref="P:NodaTime.DateTimeZone.Utc" /> property on this class. </para> <para> To obtain a <see cref="T:NodaTime.DateTimeZone" /> representing the system default time zone, you can either call <see cref="M:NodaTime.IDateTimeZoneProvider.GetSystemDefault" /> on a provider to obtain the <see cref="T:NodaTime.DateTimeZone" /> that the provider considers matches the system default time zone, or you can construct a <see cref="T:NodaTime.TimeZones.BclDateTimeZone" /> via <see cref="M:NodaTime.TimeZones.BclDateTimeZone.ForSystemDefault" />, which returns a <see cref="T:NodaTime.DateTimeZone" /> that wraps the system local <see cref="T:System.TimeZoneInfo" />. The latter will always succeed, but has access only to that information available via the .NET time zone; the former may contain more complete data, but may (in uncommon cases) fail to find a matching <see cref="T:NodaTime.DateTimeZone" />. Note that <c>BclDateTimeZone</c> may not be available in all versions of Noda Time 1.x and 2.x; see the class documentation for more details. </para> <para> Note that Noda Time does not require that <see cref="T:NodaTime.DateTimeZone" /> instances be singletons. Comparing two time zones for equality is not straightforward: if you care about whether two zones act the same way within a particular portion of time, use <see cref="T:NodaTime.TimeZones.ZoneEqualityComparer" />. Additional guarantees are provided by <see cref="T:NodaTime.IDateTimeZoneProvider" /> and <see cref="M:NodaTime.DateTimeZone.ForOffset(NodaTime.Offset)" />. </para>