Function

GLibTimeZonenew_identifier

Declaration

GTimeZone*
g_time_zone_new_identifier (
  const gchar* identifier
)

Description

Creates a GTimeZone corresponding to identifier. If identifier cannot be parsed or loaded, NULL is returned.

identifier can either be an RFC3339/ISO 8601 time offset or something that would pass as a valid value for the TZ environment variable (including NULL).

In Windows, identifier can also be the unlocalized name of a time zone for standard time, for example “Pacific Standard Time”.

Valid RFC3339 time offsets are "Z" (for UTC) or "±hh:mm". ISO 8601 additionally specifies "±hhmm" and "±hh". Offsets are time values to be added to Coordinated Universal Time (UTC) to get the local time.

In UNIX, the TZ environment variable typically corresponds to the name of a file in the zoneinfo database, an absolute path to a file somewhere else, or a string in “std offset [dst [offset],start[/time],end[/time]]” (POSIX) format. There are no spaces in the specification. The name of standard and daylight savings time zone must be three or more alphabetic characters. Offsets are time values to be added to local time to get Coordinated Universal Time (UTC) and should be "[±]hh[[:]mm[:ss]]". Dates are either "Jn" (Julian day with n between 1 and 365, leap years not counted), "n" (zero-based Julian day with n between 0 and 365) or "Mm.w.d" (day d (0 <= d <= 6) of week w (1 <= w <= 5) of month m (1 <= m <= 12), day 0 is a Sunday). Times are in local wall clock time, the default is 02:00:00.

In Windows, the “tzn[+|–]hh[:mm[:ss]][dzn]” format is used, but also accepts POSIX format. The Windows format uses US rules for all time zones; daylight savings time is 60 minutes behind the standard time with date and time of change taken from Pacific Standard Time. Offsets are time values to be added to the local time to get Coordinated Universal Time (UTC).

g_time_zone_new_local() calls this function with the value of the TZ environment variable. This function itself is independent of the value of TZ, but if identifier is NULL then /etc/localtime will be consulted to discover the correct time zone on UNIX and the registry will be consulted or GetTimeZoneInformation() will be used to get the local time zone on Windows.

If intervals are not available, only time zone rules from TZ environment variable or other means, then they will be computed from year 1900 to 2037. If the maximum year for the rules is available and it is greater than 2037, then it will followed instead.

See RFC3339 §5.6 for a precise definition of valid RFC3339 time offsets (the time-offset expansion) and ISO 8601 for the full list of valid time offsets. See The GNU C Library manual for an explanation of the possible values of the TZ environment variable. See Microsoft Time Zone Index Values for the list of time zones on Windows.

You should release the return value by calling g_time_zone_unref() when you are done with it.

Available since:2.68

Parameters

identifier const gchar*
 

A timezone identifier.

 The argument can be NULL.
 The data is owned by the caller of the function.
 The value is a NUL terminated UTF-8 string.

Return value

Returns: GTimeZone
 

The requested timezone, or NULL on failure.

 The caller of the function takes ownership of the data, and is responsible for freeing it.
 The return value can be NULL.