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TimeZone Class Reference

TimeZone represents a time zone offset, and also figures out daylight savings. More...

#include <timezone.h>

Class diagram for TimeZone:

SimpleTimeZone

List of all members.


Public Members

enum  EDisplayType { SHORT, LONG }
Enum for use with getDisplayName. More...

virtual ~TimeZone ()
virtual bool_t operator== (const TimeZone& that) const
Returns true if the two TimeZones are equal. More...

bool_t operator!= (const TimeZone& that) const
Returns true if the two TimeZones are NOT equal; that is, if operator==() returns false. More...

virtual int32_t getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis, UErrorCode& status) const = 0
Returns the TimeZone's adjusted GMT offset (i.e., the number of milliseconds to add to GMT to get local time in this time zone, taking daylight savings time into account) as of a particular reference date. More...

virtual int32_t getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis) const = 0
virtual int32_t getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t milliseconds, int32_t monthLength, UErrorCode& status) const = 0
Gets the time zone offset, for current date, modified in case of daylight savings. More...

virtual void setRawOffset (int32_t offsetMillis) = 0
Sets the TimeZone's raw GMT offset (i.e., the number of milliseconds to add to GMT to get local time, before taking daylight savings time into account). More...

virtual int32_t getRawOffset (void) const = 0
Returns the TimeZone's raw GMT offset (i.e., the number of milliseconds to add to GMT to get local time, before taking daylight savings time into account). More...

UnicodeStringgetID (UnicodeString& ID) const
Fills in "ID" with the TimeZone's ID. More...

void setID (const UnicodeString& ID)
Sets the TimeZone's ID to the specified value. More...

UnicodeStringgetDisplayName (UnicodeString& result) const
Returns a name of this time zone suitable for presentation to the user in the default locale. More...

UnicodeStringgetDisplayName (const Locale& locale, UnicodeString& result) const
Returns a name of this time zone suitable for presentation to the user in the specified locale. More...

UnicodeStringgetDisplayName (bool_t daylight, EDisplayType style, UnicodeString& result) const
Returns a name of this time zone suitable for presentation to the user in the default locale. More...

UnicodeStringgetDisplayName (bool_t daylight, EDisplayType style, const Locale& locale, UnicodeString& result) const
Returns a name of this time zone suitable for presentation to the user in the specified locale. More...

virtual bool_t useDaylightTime (void) const = 0
Queries if this time zone uses daylight savings time. More...

virtual bool_t inDaylightTime (UDate date, UErrorCode& status) const = 0
Queries if the given date is in daylight savings time in this time zone. More...

virtual bool_t hasSameRules (const TimeZone& other) const
Returns true if this zone has the same rule and offset as another zone. More...

virtual TimeZone* clone (void) const = 0
Clones TimeZone objects polymorphically. More...

virtual UClassID getDynamicClassID (void) const = 0
Returns a unique class ID POLYMORPHICALLY. More...


Static Public Members

TimeZone* createTimeZone (const UnicodeString& ID)
Creates a TimeZone for the given ID. More...

const UnicodeString** const createAvailableIDs (int32_t rawOffset, int32_t& numIDs)
Returns a list of time zone IDs, one for each time zone with a given GMT offset. More...

const UnicodeString** const createAvailableIDs (int32_t& numIDs)
Returns a list of all time zone IDs supported by the TimeZone class (i.e., all IDs that it's legal to pass to createTimeZone()). More...

TimeZone* createDefault (void)
Creates a new copy of the default TimeZone for this host. More...

void adoptDefault (TimeZone* zone)
Sets the default time zone (i.e., what's returned by getDefault()) to be the specified time zone. More...

void setDefault (const TimeZone& zone)
Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted; the caller remains responsible for deleting it. More...

UClassID getStaticClassID (void)
Return the class ID for this class. More...

const TimeZone* GMT
The GMT zone has a raw offset of zero and does not use daylight savings time.


Protected Members

 TimeZone ()
Default constructor. More...

 TimeZone (const TimeZone& source)
Copy constructor. More...

TimeZone& operator= (const TimeZone& right)
Default assignment operator. More...


Detailed Description

TimeZone represents a time zone offset, and also figures out daylight savings.

Typically, you get a TimeZone using createDefault which creates a TimeZone based on the time zone where the program is running. For example, for a program running in Japan, createDefault creates a TimeZone object based on Japanese Standard Time.

You can also get a TimeZone using createTimeZone along with a time zone ID. For instance, the time zone ID for the Pacific Standard Time zone is "PST". So, you can get a PST TimeZone object with:

You can use getAvailableIDs method to iterate through all the supported time zone IDs. You can then choose a supported ID to get a TimeZone. If the time zone you want is not represented by one of the supported IDs, then you can create a custom time zone ID with the following syntax:

 GMT[+|-]hh[[:]mm]
 

For example, you might specify GMT+14:00 as a custom time zone ID. The TimeZone that is returned when you specify a custom time zone ID does not include daylight savings time.

TimeZone is an abstract class representing a time zone. A TimeZone is needed for Calendar to produce local time for a particular time zone. A TimeZone comprises three basic pieces of information:

(Only the ID is actually implemented in TimeZone; subclasses of TimeZone may handle daylight savings time and GMT offset in different ways. Currently we only have one TimeZone subclass: SimpleTimeZone.)

The TimeZone class contains a static list containing a TimeZone object for every combination of GMT offset and daylight-savings time rules currently in use in the world, each with a unique ID. Each ID consists of a region (usually a continent or ocean) and a city in that region, separated by a slash, (for example, Pacific Standard Time is "America/Los_Angeles.") Because older versions of this class used three- or four-letter abbreviations instead, there is also a table that maps the older abbreviations to the newer ones (for example, "PST" maps to "America/LosAngeles"). Anywhere the API requires an ID, you can use either form.

To create a new TimeZone, you call the factory function TimeZone::createTimeZone() and pass it a time zone ID. You can use the createAvailableIDs() function to obtain a list of all the time zone IDs recognized by createTimeZone().

You can also use TimeZone::createDefault() to create a TimeZone. This function uses platform-specific APIs to produce a TimeZone for the time zone corresponding to the client's computer's physical location. For example, if you're in Japan (assuming your machine is set up correctly), TimeZone::createDefault() will return a TimeZone for Japanese Standard Time ("Asia/Tokyo").


Member Enumeration Documentation

enum TimeZone::EDisplayType

Enum for use with getDisplayName.

Enumeration values:
SHORT  
LONG  

Member Function Documentation

virtual TimeZone::~TimeZone () [virtual]

Stable:

virtual bool_t TimeZone::operator== (const TimeZone & that) const [virtual]

Returns true if the two TimeZones are equal.

(The TimeZone version only compares IDs, but subclasses are expected to also compare the fields they add.)

Parameters:
that   The TimeZone object to be compared with.
Returns:
True if the given TimeZone is equal to this TimeZone; false otherwise.
Stable:

Reimplemented in SimpleTimeZone.

bool_t TimeZone::operator!= (const TimeZone & that) const [inline]

Returns true if the two TimeZones are NOT equal; that is, if operator==() returns false.

Parameters:
that   The TimeZone object to be compared with.
Returns:
True if the given TimeZone is not equal to this TimeZone; false otherwise.
Stable:

virtual int32_t TimeZone::getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis, UErrorCode & status) const [pure virtual]

Returns the TimeZone's adjusted GMT offset (i.e., the number of milliseconds to add to GMT to get local time in this time zone, taking daylight savings time into account) as of a particular reference date.

The reference date is used to determine whether daylight savings time is in effect and needs to be figured into the offset that is returned (in other words, what is the adjusted GMT offset in this time zone at this particular date and time?). For the time zones produced by createTimeZone(), the reference data is specified according to the Gregorian calendar, and the date and time fields are in GMT, NOT local time.

Parameters:
era   The reference date's era
year   The reference date's year
month   The reference date's month (0-based; 0 is January)
day   The reference date's day-in-month (1-based)
dayOfWeek   The reference date's day-of-week (1-based; 1 is Sunday)
millis   The reference date's milliseconds in day, UTT (NOT local time).
Returns:
The offset in milliseconds to add to GMT to get local time.
Stable:

Reimplemented in SimpleTimeZone.

virtual int32_t TimeZone::getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis) const [pure virtual]

Deprecated:

Reimplemented in SimpleTimeZone.

virtual int32_t TimeZone::getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t milliseconds, int32_t monthLength, UErrorCode & status) const [pure virtual]

Gets the time zone offset, for current date, modified in case of daylight savings.

This is the offset to add *to* UTC to get local time.

Parameters:
era   the era of the given date.
year   the year in the given date.
month   the month in the given date. Month is 0-based. e.g., 0 for January.
day   the day-in-month of the given date.
dayOfWeek   the day-of-week of the given date.
milliseconds   the millis in day in standard local time.
monthLength   the length of the given month in days.
Returns:
the offset to add *to* GMT to get local time.
Stable:

Reimplemented in SimpleTimeZone.

virtual void TimeZone::setRawOffset (int32_t offsetMillis) [pure virtual]

Sets the TimeZone's raw GMT offset (i.e., the number of milliseconds to add to GMT to get local time, before taking daylight savings time into account).

Parameters:
offsetMillis   The new raw GMT offset for this time zone.
Stable:

Reimplemented in SimpleTimeZone.

virtual int32_t TimeZone::getRawOffset (void) const [pure virtual]

Returns the TimeZone's raw GMT offset (i.e., the number of milliseconds to add to GMT to get local time, before taking daylight savings time into account).

Returns:
The TimeZone's raw GMT offset.
Stable:

Reimplemented in SimpleTimeZone.

UnicodeString & TimeZone::getID (UnicodeString & ID) const [inline]

Fills in "ID" with the TimeZone's ID.

Parameters:
ID   Receives this TimeZone's ID.
Returns:
"ID"
Stable:

void TimeZone::setID (const UnicodeString & ID) [inline]

Sets the TimeZone's ID to the specified value.

This doesn't affect any other fields (for example, if you say< blockquote>

 .     TimeZone* foo = TimeZone::createTimeZone("America/New_York");
 .     foo.setID("America/Los_Angeles");
 
the time zone's GMT offset and daylight-savings rules don't change to those for Los Angeles. They're still those for New York. Only the ID has changed.)

Parameters:
ID   The new timezone ID.
Stable:

UnicodeString & TimeZone::getDisplayName (UnicodeString & result) const

Returns a name of this time zone suitable for presentation to the user in the default locale.

This method returns the long name, not including daylight savings. If the display name is not available for the locale, then this method returns a string in the format GMT[+-]hh:mm.

Returns:
the human-readable name of this time zone in the default locale.
Stable:

UnicodeString & TimeZone::getDisplayName (const Locale & locale, UnicodeString & result) const

Returns a name of this time zone suitable for presentation to the user in the specified locale.

This method returns the long name, not including daylight savings. If the display name is not available for the locale, then this method returns a string in the format GMT[+-]hh:mm.

Parameters:
locale   the locale in which to supply the display name.
Returns:
the human-readable name of this time zone in the given locale or in the default locale if the given locale is not recognized.
Stable:

UnicodeString & TimeZone::getDisplayName (bool_t daylight, EDisplayType style, UnicodeString & result) const

Returns a name of this time zone suitable for presentation to the user in the default locale.

If the display name is not available for the locale, then this method returns a string in the format GMT[+-]hh:mm.

Parameters:
daylight   if true, return the daylight savings name.
style   either LONG or SHORT
Returns:
the human-readable name of this time zone in the default locale.
Stable:

UnicodeString & TimeZone::getDisplayName (bool_t daylight, EDisplayType style, const Locale & locale, UnicodeString & result) const

Returns a name of this time zone suitable for presentation to the user in the specified locale.

If the display name is not available for the locale, then this method returns a string in the format GMT[+-]hh:mm.

Parameters:
daylight   if true, return the daylight savings name.
style   either LONG or SHORT
locale   the locale in which to supply the display name.
Returns:
the human-readable name of this time zone in the given locale or in the default locale if the given locale is not recognized.
Stable:

virtual bool_t TimeZone::useDaylightTime (void) const [pure virtual]

Queries if this time zone uses daylight savings time.

Returns:
true if this time zone uses daylight savings time, false, otherwise.
Stable:

Reimplemented in SimpleTimeZone.

virtual bool_t TimeZone::inDaylightTime (UDate date, UErrorCode & status) const [pure virtual]

Queries if the given date is in daylight savings time in this time zone.

Parameters:
date   the given UDate.
Returns:
true if the given date is in daylight savings time, false, otherwise.
Deprecated:

Reimplemented in SimpleTimeZone.

virtual bool_t TimeZone::hasSameRules (const TimeZone & other) const [virtual]

Returns true if this zone has the same rule and offset as another zone.

That is, if this zone differs only in ID, if at all.

Parameters:
other   the TimeZone object to be compared with
Returns:
true if the given zone is the same as this one, with the possible exception of the ID
Stable:

Reimplemented in SimpleTimeZone.

virtual TimeZone * TimeZone::clone (void) const [pure virtual]

Clones TimeZone objects polymorphically.

Clients are responsible for deleting the TimeZone object cloned.

Returns:
A new copy of this TimeZone object.
Stable:

Reimplemented in SimpleTimeZone.

virtual UClassID TimeZone::getDynamicClassID (void) const [pure virtual]

Returns a unique class ID POLYMORPHICALLY.

Pure virtual method. This method is to implement a simple version of RTTI, since not all C++ compilers support genuine RTTI. Polymorphic operator==() and clone() methods call this method.

Concrete subclasses of TimeZone must implement getDynamicClassID() and also a static method and data member:

 .     static UClassID getStaticClassID() { return (UClassID)&fgClassID; }
 .     static char fgClassID;
 
Returns:
The class ID for this object. All objects of a given class have the same class ID. Objects of other classes have different class IDs.
Stable:

Reimplemented in SimpleTimeZone.

TimeZone * TimeZone::createTimeZone (const UnicodeString & ID) [static]

Creates a TimeZone for the given ID.

Parameters:
ID   the ID for a TimeZone, either an abbreviation such as "PST", a full name such as "America/Los_Angeles", or a custom ID such as "GMT-8:00".
Returns:
the specified TimeZone, or the GMT zone if the given ID cannot be understood. Return result guaranteed to be non-null. If you require that the specific zone asked for be returned, check the ID of the return result.
Stable:

const UnicodeString **const TimeZone::createAvailableIDs (int32_t rawOffset, int32_t & numIDs) [static]

Returns a list of time zone IDs, one for each time zone with a given GMT offset.

The return value is a list because there may be several times zones with the same GMT offset that differ in the way they handle daylight savings time. For example, the state of Arizona doesn't observe Daylight Savings time. So if you ask for the time zone IDs corresponding to GMT-7:00, you'll get back two time zone IDs: "America/Denver," which corresponds to Mountain Standard Time in the winter and Mountain Daylight Time in the summer, and "America/Phoenix", which corresponds to Mountain Standard Time year-round, even in the summer.

The caller owns the list that is returned, but does not own the strings contained in that list. Delete the array, but DON'T delete the elements in the array.

Parameters:
rawOffset   An offset from GMT in milliseconds.
numIDs   Receives the number of items in the array that is returned.
Returns:
An array of UnicodeString pointers, where each UnicodeString is a time zone ID for a time zone with the given GMT offset. If there is no timezone that matches the GMT offset specified, NULL is returned.
Stable:

const UnicodeString **const TimeZone::createAvailableIDs (int32_t & numIDs) [static]

Returns a list of all time zone IDs supported by the TimeZone class (i.e., all IDs that it's legal to pass to createTimeZone()).

The caller owns the list that is returned, but does not own the strings contained in that list. Delete the array, but DON'T delete the elements in the array.

Parameters:
numIDs   Receives the number of zone IDs returned.
Returns:
An array of UnicodeString pointers, where each is a time zone ID supported by the TimeZone class.
Stable:

TimeZone * TimeZone::createDefault (void) [static]

Creates a new copy of the default TimeZone for this host.

Unless the default time zone has already been set using adoptDefault() or setDefault(), the default is determined by querying the system using methods in TPlatformUtilities. If the system routines fail, or if they specify a TimeZone or TimeZone offset which is not recognized, the TimeZone indicated by the ID kLastResortID is instantiated and made the default.

Returns:
A default TimeZone. Clients are responsible for deleting the time zone object returned.
Stable:

void TimeZone::adoptDefault (TimeZone * zone) [static]

Sets the default time zone (i.e., what's returned by getDefault()) to be the specified time zone.

If NULL is specified for the time zone, the default time zone is set to the default host time zone. This call adopts the TimeZone object passed in; the clent is no longer responsible for deleting it.

Parameters:
zone   A pointer to the new TimeZone object to use as the default.
Stable:

void TimeZone::setDefault (const TimeZone & zone) [static]

Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted; the caller remains responsible for deleting it.

Parameters:
zone   The given timezone.
System:

UClassID TimeZone::getStaticClassID (void) [inline, static]

Return the class ID for this class.

This is useful only for comparing to a return value from getDynamicClassID(). For example:

 .   Base* polymorphic_pointer = createPolymorphicObject();
 .   if (polymorphic_pointer->getDynamicClassID() ==
 .       Derived::getStaticClassID()) ...
 
Returns:
The class ID for all objects of this class.
Stable:

Reimplemented in SimpleTimeZone.

TimeZone::TimeZone () [protected]

Default constructor.

ID is initialized to the empty string.

Stable:

TimeZone::TimeZone (const TimeZone & source) [protected]

Copy constructor.

Stable:

TimeZone & TimeZone::operator= (const TimeZone & right) [protected]

Default assignment operator.

Stable:

Member Data Documentation

const TimeZone* TimeZone::GMT [static]

The GMT zone has a raw offset of zero and does not use daylight savings time.


The documentation for this class was generated from the following file:
Generated at Thu Feb 10 15:31:02 2000 for icu by doxygen 1.0.0 written by Dimitri van Heesch, © 1997-1999