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Class std.datetime.timezone.WindowsTimeZone

This class is Windows-Only.

class WindowsTimeZone
  : TimeZone ;

Represents a time zone from the Windows registry. Unfortunately, Windows does not use the TZ Database. To use the TZ Database, use PosixTimeZone (which reads its information from the TZ Database files on disk) on Windows by providing the TZ Database files and telling PosixTimeZone.getTimeZone where the directory holding them is.

The TZ Database files and Windows' time zone information frequently do not match. Windows has many errors with regards to when DST switches occur (especially for historical dates). Also, the TZ Database files include far more time zones than Windows does. So, for accurate time zone information, use the TZ Database files with PosixTimeZone rather than WindowsTimeZone. However, because WindowsTimeZone uses Windows system calls to deal with the time, it's far more likely to match the behavior of other Windows programs. Be aware of the differences when selecting a method.

WindowsTimeZone does not exist on Posix systems.

To get a WindowsTimeZone, call WindowsTimeZone.getTimeZone.


hasDST[get] boolWhether this time zone has Daylight Savings Time at any point in time. Note that for some time zone types it may not have DST for current dates but will still return true for hasDST because the time zone did at some point have DST.
dstName[get] stringTypically, the abbreviation (generally 3 or 4 letters) for the time zone when DST is in effect (e.g. PDT). It is not necessarily unique.
name[get] stringThe name of the time zone. Exactly how the time zone name is formatted depends on the derived class. In the case of PosixTimeZone, it's the TZ Database name, whereas with WindowsTimeZone, it's the name that Windows chose to give the registry key for that time zone (typically the name that they give stdTime if the OS is in English). For other time zone types, what it is depends on how they're implemented.
stdName[get] stringTypically, the abbreviation (generally 3 or 4 letters) for the time zone when DST is not in effect (e.g. PST). It is not necessarily unique.


dstInEffect Takes the number of hnsecs (100 ns) since midnight, January 1st, 1 A.D. in UTC time (i.e. std time) and returns whether DST is in effect in this time zone at the given point in time.
getInstalledTZNames Returns a list of the names of the time zones installed on the system. The list returned by WindowsTimeZone contains the Windows TZ names, not the TZ Database names. However, TimeZone.getinstalledTZNames will return the TZ Database names which are equivalent to the Windows TZ names.
getTimeZone Returns a TimeZone with the given name per the Windows time zone names. The time zone information is fetched from the Windows registry.
tzToUTC Takes the number of hnsecs (100 ns) since midnight, January 1st, 1 A.D. in this time zone's time and converts it to UTC (i.e. std time).
utcToTZ Takes the number of hnsecs (100 ns) since midnight, January 1st, 1 A.D. in UTC time (i.e. std time) and converts it to this time zone's time.
factory Create instance of class specified by the fully qualified name classname. The class must either have no constructors or have a default constructor.
opCmp Compare with another Object obj.
opEquals Test whether this is equal to o. The default implementation only compares by identity (using the is operator). Generally, overrides for opEquals should attempt to compare objects by their contents.
toHash Compute hash function for Object.
toString Convert Object to a human readable string.
utcOffsetAt Returns what the offset from UTC is at the given std time. It includes the DST offset in effect at that time (if any).

See Also

Home of the TZ Database files


Jonathan M Davis


Boost License 1.0.