Main Page | Class Hierarchy | Alphabetical List | Data Structures | Directories | File List | Data Fields | Globals | Related Pages

GregorianCalendar Class Reference

Concrete class which provides the standard calendar used by most of the world. More...

#include <gregocal.h>

Inheritance diagram for GregorianCalendar:

Calendar

Public Types

enum  EEras { BC, AD }
 Useful constants for GregorianCalendar and TimeZone. More...

Public Member Functions

 GregorianCalendar (UErrorCode &success)
 Constructs a default GregorianCalendar using the current time in the default time zone with the default locale.
 GregorianCalendar (TimeZone *zoneToAdopt, UErrorCode &success)
 Constructs a GregorianCalendar based on the current time in the given time zone with the default locale.
 GregorianCalendar (const TimeZone &zone, UErrorCode &success)
 Constructs a GregorianCalendar based on the current time in the given time zone with the default locale.
 GregorianCalendar (const Locale &aLocale, UErrorCode &success)
 Constructs a GregorianCalendar based on the current time in the default time zone with the given locale.
 GregorianCalendar (TimeZone *zoneToAdopt, const Locale &aLocale, UErrorCode &success)
 Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.
 GregorianCalendar (const TimeZone &zone, const Locale &aLocale, UErrorCode &success)
 Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.
 GregorianCalendar (int32_t year, int32_t month, int32_t date, UErrorCode &success)
 Constructs a GregorianCalendar with the given AD date set in the default time zone with the default locale.
 GregorianCalendar (int32_t year, int32_t month, int32_t date, int32_t hour, int32_t minute, UErrorCode &success)
 Constructs a GregorianCalendar with the given AD date and time set for the default time zone with the default locale.
 GregorianCalendar (int32_t year, int32_t month, int32_t date, int32_t hour, int32_t minute, int32_t second, UErrorCode &success)
 Constructs a GregorianCalendar with the given AD date and time set for the default time zone with the default locale.
virtual ~GregorianCalendar ()
 Destructor .
 GregorianCalendar (const GregorianCalendar &source)
 Copy constructor .
GregorianCalendaroperator= (const GregorianCalendar &right)
 Default assignment operator .
virtual Calendarclone (void) const
 Create and return a polymorphic copy of this calendar.
void setGregorianChange (UDate date, UErrorCode &success)
 Sets the GregorianCalendar change date.
UDate getGregorianChange (void) const
 Gets the Gregorian Calendar change date.
UBool isLeapYear (int32_t year) const
 Return true if the given year is a leap year.
virtual UBool operator== (const Calendar &that) const
 Compares the equality of two GregorianCalendar objects.
virtual UBool equivalentTo (const Calendar &other) const
 Calendar override.
virtual void add (EDateFields field, int32_t amount, UErrorCode &status)
 (Overrides Calendar) UDate Arithmetic function.
virtual void roll (EDateFields field, int32_t amount, UErrorCode &status)
 (Overrides Calendar) Rolls up or down by the given amount in the specified field.
virtual int32_t getMinimum (EDateFields field) const
 (Overrides Calendar) Returns minimum value for the given field.
virtual int32_t getMaximum (EDateFields field) const
 (Overrides Calendar) Returns maximum value for the given field.
virtual int32_t getGreatestMinimum (EDateFields field) const
 (Overrides Calendar) Returns highest minimum value for the given field if varies.
virtual int32_t getLeastMaximum (EDateFields field) const
 (Overrides Calendar) Returns lowest maximum value for the given field if varies.
int32_t getActualMinimum (EDateFields field) const
 Return the minimum value that this field could have, given the current date.
int32_t getActualMaximum (EDateFields field) const
 Return the maximum value that this field could have, given the current date.
virtual UBool inDaylightTime (UErrorCode &status) const
 (Overrides Calendar) Return true if the current date for this Calendar is in Daylight Savings Time.
virtual UClassID getDynamicClassID (void) const
 Override Calendar Returns a unique class ID POLYMORPHICALLY.

Static Public Member Functions

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

Protected Member Functions

virtual void computeFields (UErrorCode &status)
 (Overrides Calendar) Converts GMT as milliseconds to time field values.
virtual void computeTime (UErrorCode &status)
 (Overrides Calendar) Converts Calendar's time field values to GMT as milliseconds.

Detailed Description

Concrete class which provides the standard calendar used by most of the world.

The standard (Gregorian) calendar has 2 eras, BC and AD.

This implementation handles a single discontinuity, which corresponds by default to the date the Gregorian calendar was originally instituted (October 15, 1582). Not all countries adopted the Gregorian calendar then, so this cutover date may be changed by the caller.

Prior to the institution of the Gregorian Calendar, New Year's Day was March 25. To avoid confusion, this Calendar always uses January 1. A manual adjustment may be made if desired for dates that are prior to the Gregorian changeover and which fall between January 1 and March 24.

Values calculated for the WEEK_OF_YEAR field range from 1 to 53. Week 1 for a year is the first week that contains at least getMinimalDaysInFirstWeek() days from that year. It thus depends on the values of getMinimalDaysInFirstWeek(), getFirstDayOfWeek(), and the day of the week of January 1. Weeks between week 1 of one year and week 1 of the following year are numbered sequentially from 2 to 52 or 53 (as needed).

For example, January 1, 1998 was a Thursday. If getFirstDayOfWeek() is MONDAY and getMinimalDaysInFirstWeek() is 4 (these are the values reflecting ISO 8601 and many national standards), then week 1 of 1998 starts on December 29, 1997, and ends on January 4, 1998. If, however, getFirstDayOfWeek() is SUNDAY, then week 1 of 1998 starts on January 4, 1998, and ends on January 10, 1998; the first three days of 1998 then are part of week 53 of 1997.

Example for using GregorianCalendar:

     // get the supported ids for GMT-08:00 (Pacific Standard Time)
     int32_t idsCount;
     const UnicodeString** ids = TimeZone::createAvailableIDs(-8 * 60 * 60 * 1000, idsCount);
     // if no ids were returned, something is wrong. get out.
     if (idsCount == 0) {
         return;
     }

     // begin output
     cout << "Current Time" << endl;

     // create a Pacific Standard Time time zone
     SimpleTimeZone* pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000, *(ids[0]));

     // set up rules for daylight savings time
     pdt->setStartRule(Calendar::APRIL, 1, Calendar::SUNDAY, 2 * 60 * 60 * 1000);
     pdt->setEndRule(Calendar::OCTOBER, -1, Calendar::SUNDAY, 2 * 60 * 60 * 1000);

     // create a GregorianCalendar with the Pacific Daylight time zone
     // and the current date and time
     UErrorCode success = U_ZERO_ERROR;
     Calendar* calendar = new GregorianCalendar( pdt, success );

     // print out a bunch of interesting things
     cout << "ERA: " << calendar->get( Calendar::ERA, success ) << endl;
     cout << "YEAR: " << calendar->get( Calendar::YEAR, success ) << endl;
     cout << "MONTH: " << calendar->get( Calendar::MONTH, success ) << endl;
     cout << "WEEK_OF_YEAR: " << calendar->get( Calendar::WEEK_OF_YEAR, success ) << endl;
     cout << "WEEK_OF_MONTH: " << calendar->get( Calendar::WEEK_OF_MONTH, success ) << endl;
     cout << "DATE: " << calendar->get( Calendar::DATE, success ) << endl;
     cout << "DAY_OF_MONTH: " << calendar->get( Calendar::DAY_OF_MONTH, success ) << endl;
     cout << "DAY_OF_YEAR: " << calendar->get( Calendar::DAY_OF_YEAR, success ) << endl;
     cout << "DAY_OF_WEEK: " << calendar->get( Calendar::DAY_OF_WEEK, success ) << endl;
     cout << "DAY_OF_WEEK_IN_MONTH: " << calendar->get( Calendar::DAY_OF_WEEK_IN_MONTH, success ) << endl;
     cout << "AM_PM: " << calendar->get( Calendar::AM_PM, success ) << endl;
     cout << "HOUR: " << calendar->get( Calendar::HOUR, success ) << endl;
     cout << "HOUR_OF_DAY: " << calendar->get( Calendar::HOUR_OF_DAY, success ) << endl;
     cout << "MINUTE: " << calendar->get( Calendar::MINUTE, success ) << endl;
     cout << "SECOND: " << calendar->get( Calendar::SECOND, success ) << endl;
     cout << "MILLISECOND: " << calendar->get( Calendar::MILLISECOND, success ) << endl;
     cout << "ZONE_OFFSET: " << (calendar->get( Calendar::ZONE_OFFSET, success )/(60*60*1000)) << endl;
     cout << "DST_OFFSET: " << (calendar->get( Calendar::DST_OFFSET, success )/(60*60*1000)) << endl;

     cout << "Current Time, with hour reset to 3" << endl;
     calendar->clear(Calendar::HOUR_OF_DAY); // so doesn't override
     calendar->set(Calendar::HOUR, 3);
     cout << "ERA: " << calendar->get( Calendar::ERA, success ) << endl;
     cout << "YEAR: " << calendar->get( Calendar::YEAR, success ) << endl;
     cout << "MONTH: " << calendar->get( Calendar::MONTH, success ) << endl;
     cout << "WEEK_OF_YEAR: " << calendar->get( Calendar::WEEK_OF_YEAR, success ) << endl;
     cout << "WEEK_OF_MONTH: " << calendar->get( Calendar::WEEK_OF_MONTH, success ) << endl;
     cout << "DATE: " << calendar->get( Calendar::DATE, success ) << endl;
     cout << "DAY_OF_MONTH: " << calendar->get( Calendar::DAY_OF_MONTH, success ) << endl;
     cout << "DAY_OF_YEAR: " << calendar->get( Calendar::DAY_OF_YEAR, success ) << endl;
     cout << "DAY_OF_WEEK: " << calendar->get( Calendar::DAY_OF_WEEK, success ) << endl;
     cout << "DAY_OF_WEEK_IN_MONTH: " << calendar->get( Calendar::DAY_OF_WEEK_IN_MONTH, success ) << endl;
     cout << "AM_PM: " << calendar->get( Calendar::AM_PM, success ) << endl;
     cout << "HOUR: " << calendar->get( Calendar::HOUR, success ) << endl;
     cout << "HOUR_OF_DAY: " << calendar->get( Calendar::HOUR_OF_DAY, success ) << endl;
     cout << "MINUTE: " << calendar->get( Calendar::MINUTE, success ) << endl;
     cout << "SECOND: " << calendar->get( Calendar::SECOND, success ) << endl;
     cout << "MILLISECOND: " << calendar->get( Calendar::MILLISECOND, success ) << endl;
     cout << "ZONE_OFFSET: " << (calendar->get( Calendar::ZONE_OFFSET, success )/(60*60*1000)) << endl; // in hours
     cout << "DST_OFFSET: " << (calendar->get( Calendar::DST_OFFSET, success )/(60*60*1000)) << endl; // in hours

     delete[] ids;
     delete calendar; // also deletes pdt


Member Enumeration Documentation

enum GregorianCalendar::EEras
 

Useful constants for GregorianCalendar and TimeZone.


Constructor & Destructor Documentation

GregorianCalendar::GregorianCalendar UErrorCode success  ) 
 

Constructs a default GregorianCalendar using the current time in the default time zone with the default locale.

Parameters:
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar TimeZone zoneToAdopt,
UErrorCode success
 

Constructs a GregorianCalendar based on the current time in the given time zone with the default locale.

Clients are no longer responsible for deleting the given time zone object after it's adopted.

Parameters:
zoneToAdopt The given timezone.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar const TimeZone zone,
UErrorCode success
 

Constructs a GregorianCalendar based on the current time in the given time zone with the default locale.

Parameters:
zone The given timezone.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar const Locale &  aLocale,
UErrorCode success
 

Constructs a GregorianCalendar based on the current time in the default time zone with the given locale.

Parameters:
aLocale The given locale.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar TimeZone zoneToAdopt,
const Locale &  aLocale,
UErrorCode success
 

Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.

Clients are no longer responsible for deleting the given time zone object after it's adopted.

Parameters:
zoneToAdopt The given timezone.
aLocale The given locale.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar const TimeZone zone,
const Locale &  aLocale,
UErrorCode success
 

Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.

Parameters:
zone The given timezone.
aLocale The given locale.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar int32_t  year,
int32_t  month,
int32_t  date,
UErrorCode success
 

Constructs a GregorianCalendar with the given AD date set in the default time zone with the default locale.

Parameters:
year The value used to set the YEAR time field in the calendar.
month The value used to set the MONTH time field in the calendar. Month value is 0-based. e.g., 0 for January.
date The value used to set the DATE time field in the calendar.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar int32_t  year,
int32_t  month,
int32_t  date,
int32_t  hour,
int32_t  minute,
UErrorCode success
 

Constructs a GregorianCalendar with the given AD date and time set for the default time zone with the default locale.

Parameters:
year The value used to set the YEAR time field in the calendar.
month The value used to set the MONTH time field in the calendar. Month value is 0-based. e.g., 0 for January.
date The value used to set the DATE time field in the calendar.
hour The value used to set the HOUR_OF_DAY time field in the calendar.
minute The value used to set the MINUTE time field in the calendar.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.

GregorianCalendar::GregorianCalendar int32_t  year,
int32_t  month,
int32_t  date,
int32_t  hour,
int32_t  minute,
int32_t  second,
UErrorCode success
 

Constructs a GregorianCalendar with the given AD date and time set for the default time zone with the default locale.

Parameters:
year The value used to set the YEAR time field in the calendar.
month The value used to set the MONTH time field in the calendar. Month value is 0-based. e.g., 0 for January.
date The value used to set the DATE time field in the calendar.
hour The value used to set the HOUR_OF_DAY time field in the calendar.
minute The value used to set the MINUTE time field in the calendar.
second The value used to set the SECOND time field in the calendar.
success Indicates the status of GregorianCalendar object construction. Returns U_ZERO_ERROR if constructed successfully.


Member Function Documentation

virtual void GregorianCalendar::add EDateFields  field,
int32_t  amount,
UErrorCode status
[virtual]
 

(Overrides Calendar) UDate Arithmetic function.

Adds the specified (signed) amount of time to the given time field, based on the calendar's rules. For more information, see the documentation for Calendar::add().

Parameters:
field The time field.
amount The amount of date or time to be added to the field.
status Output param set to success/failure code on exit. If any value previously set in the time field is invalid, this will be set to an error status.

Implements Calendar.

virtual Calendar* GregorianCalendar::clone void   )  const [virtual]
 

Create and return a polymorphic copy of this calendar.

Implements Calendar.

virtual void GregorianCalendar::computeFields UErrorCode status  )  [protected, virtual]
 

(Overrides Calendar) Converts GMT as milliseconds to time field values.

Implements Calendar.

virtual void GregorianCalendar::computeTime UErrorCode status  )  [protected, virtual]
 

(Overrides Calendar) Converts Calendar's time field values to GMT as milliseconds.

Parameters:
status Output param set to success/failure code on exit. If any value previously set in the time field is invalid, this will be set to an error status.

Implements Calendar.

virtual UBool GregorianCalendar::equivalentTo const Calendar other  )  const [virtual]
 

Calendar override.

Return true if another Calendar object is equivalent to this one. An equivalent Calendar will behave exactly as this one does, but may be set to a different time.

Reimplemented from Calendar.

int32_t GregorianCalendar::getActualMaximum EDateFields  field  )  const
 

Return the maximum value that this field could have, given the current date.

For example, with the date "Feb 3, 1997" and the DAY_OF_MONTH field, the actual maximum would be 28; for "Feb 3, 1996" it s 29. Similarly for a Hebrew calendar, for some years the actual maximum for MONTH is 12, and for others 13.

int32_t GregorianCalendar::getActualMinimum EDateFields  field  )  const
 

Return the minimum value that this field could have, given the current date.

For the Gregorian calendar, this is the same as getMinimum() and getGreatestMinimum().

virtual UClassID GregorianCalendar::getDynamicClassID void   )  const [inline, virtual]
 

Override Calendar Returns a unique class ID POLYMORPHICALLY.

Pure virtual override. 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.

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.

Implements Calendar.

virtual int32_t GregorianCalendar::getGreatestMinimum EDateFields  field  )  const [virtual]
 

(Overrides Calendar) Returns highest minimum value for the given field if varies.

Otherwise same as getMinimum(). For Gregorian, no difference.

Implements Calendar.

UDate GregorianCalendar::getGregorianChange void   )  const
 

Gets the Gregorian Calendar change date.

This is the point when the switch from Julian dates to Gregorian dates occurred. Default is 00:00:00 local time, October 15, 1582. Previous to this time and date will be Julian dates.

Returns:
The Gregorian cutover time for this calendar.

virtual int32_t GregorianCalendar::getLeastMaximum EDateFields  field  )  const [virtual]
 

(Overrides Calendar) Returns lowest maximum value for the given field if varies.

Otherwise same as getMaximum(). For Gregorian DAY_OF_MONTH, 28.

Implements Calendar.

virtual int32_t GregorianCalendar::getMaximum EDateFields  field  )  const [virtual]
 

(Overrides Calendar) Returns maximum value for the given field.

e.g. for Gregorian DAY_OF_MONTH, 31.

Implements Calendar.

virtual int32_t GregorianCalendar::getMinimum EDateFields  field  )  const [virtual]
 

(Overrides Calendar) Returns minimum value for the given field.

e.g. for Gregorian DAY_OF_MONTH, 1.

Implements Calendar.

static UClassID GregorianCalendar::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.

virtual UBool GregorianCalendar::inDaylightTime UErrorCode status  )  const [virtual]
 

(Overrides Calendar) Return true if the current date for this Calendar is in Daylight Savings Time.

Recognizes DST_OFFSET, if it is set.

Parameters:
status Fill-in parameter which receives the status of this operation.
Returns:
True if the current date for this Calendar is in Daylight Savings Time, false, otherwise.

Implements Calendar.

UBool GregorianCalendar::isLeapYear int32_t  year  )  const
 

Return true if the given year is a leap year.

Determination of whether a year is a leap year is actually very complicated. We do something crude and mostly correct here, but for a real determination you need a lot of contextual information. For example, in Sweden, the change from Julian to Gregorian happened in a complex way resulting in missed leap years and double leap years between 1700 and 1753. Another example is that after the start of the Julian calendar in 45 B.C., the leap years did not regularize until 8 A.D. This method ignores these quirks, and pays attention only to the Julian onset date and the Gregorian cutover (which can be changed).

Parameters:
year The given year.
Returns:
True if the given year is a leap year; false otherwise.

virtual UBool GregorianCalendar::operator== const Calendar that  )  const [virtual]
 

Compares the equality of two GregorianCalendar objects.

Objects of different subclasses are considered unequal. This is a strict equality test; see the documentation for Calendar::operator==().

Parameters:
that The GregorianCalendar object to be compared with.
Returns:
True if the given GregorianCalendar is the same as this GregorianCalendar; false otherwise.

Reimplemented from Calendar.

virtual void GregorianCalendar::roll EDateFields  field,
int32_t  amount,
UErrorCode status
[virtual]
 

(Overrides Calendar) Rolls up or down by the given amount in the specified field.

For more information, see the documentation for Calendar::roll().

Parameters:
field The time field.
amount Indicates amount to roll.
status Output param set to success/failure code on exit. If any value previously set in the time field is invalid, this will be set to an error status.

Implements Calendar.

void GregorianCalendar::setGregorianChange UDate  date,
UErrorCode success
 

Sets the GregorianCalendar change date.

This is the point when the switch from Julian dates to Gregorian dates occurred. Default is 00:00:00 local time, October 15, 1582. Previous to this time and date will be Julian dates.

Parameters:
date The given Gregorian cutover date.
success Output param set to success/failure code on exit.


The documentation for this class was generated from the following file:
Generated on Mon Jul 25 21:51:39 2005 for ICU 2.1 by  doxygen 1.4.3-20050530