The QGregorianCalendar class implements the Gregorian calendar. More...

#include <qgregoriancalendar_p.h>

Inheritance diagram for QGregorianCalendar:

Collaboration diagram for QGregorianCalendar:

Public Member Functions
QString	name () const override
	Returns the primary name of the calendar.

bool	isLeapYear (int year) const override
	Returns `true` if the specified year is a leap year for this calendar.

bool	dateToJulianDay (int year, int month, int day, qint64 *jd) const override
	Computes the Julian day number corresponding to the specified year, month, and day.

QCalendar::YearMonthDay	julianDayToDate (qint64 jd) const override
	Computes the year, month, and day in this calendar for the given Julian day number jd.

qint64	matchCenturyToWeekday (const QCalendar::YearMonthDay &parts, int dow) const override

Public Member Functions inherited from QRomanCalendar
int	daysInMonth (int month, int year=QCalendar::Unspecified) const override
	Returns number of days in the month number month, in year year.

int	minimumDaysInMonth () const override
	Returns the minimum number of days in any valid month of any valid year.

bool	isLunar () const override
	Returns `true` if this calendar is a lunar calendar.

bool	isLuniSolar () const override
	Returns `true` if this calendar is a lunisolar calendar.

bool	isSolar () const override
	Returns `true` if this calendar is a solar calendar.

QString	monthName (const QLocale &locale, int month, int year, QLocale::FormatType format) const override
	Returns the name of the specified month in the given year for the chosen locale, using the given format to determine how complete the name is.

QString	standaloneMonthName (const QLocale &locale, int month, int year, QLocale::FormatType format) const override
	Returns the standalone name of the specified month in the chosen locale, using the specified format to determine how complete the name is.

Public Member Functions inherited from QCalendarBackend
	QCalendarBackend ()=default

virtual	~QCalendarBackend ()
	Destroys the calendar backend.

QStringList	names () const
	Returns list of names this backend was registered with.

QCalendar::System	calendarSystem () const
	The calendar system of this calendar.

QCalendar::SystemId	calendarId () const

virtual int	daysInYear (int year) const
	Returns the total number of days in the year number year.

virtual int	monthsInYear (int year) const
	Returns the total number of months in the year number year.

virtual bool	isDateValid (int year, int month, int day) const
	Returns `true` if the date specified by year, month, and day is valid for this calendar; otherwise returns `false`.

virtual bool	isProleptic () const
	Returns `true` if this calendar is a proleptic calendar.

virtual bool	hasYearZero () const
	Returns `true` if year number `0` is considered a valid year in this calendar.

virtual int	maximumDaysInMonth () const
	Returns the maximum number of days in a month for any year.

virtual int	maximumMonthsInYear () const
	Returns the maximum number of months possible in any year.

virtual int	dayOfWeek (qint64 jd) const
	Returns the day of the week for the given Julian Day Number jd.

virtual QString	weekDayName (const QLocale &locale, int day, QLocale::FormatType format) const
	Returns the name of the specified day of the week in the chosen locale, using the specified format to determine how complete the name is.

virtual QString	standaloneWeekDayName (const QLocale &locale, int day, QLocale::FormatType format) const
	Returns the standalone name of the specified day of the week in the chosen locale, using the specified format to determine how complete the name is.

virtual QString	dateTimeToString (QStringView format, const QDateTime &datetime, QDate dateOnly, QTime timeOnly, const QLocale &locale) const
	Returns a string representing a given date, time or date-time.

bool	isGregorian () const

QCalendar::SystemId	registerCustomBackend (const QStringList &names)
	Register this backend as a custom backend.

Static Public Member Functions
static QStringList	nameList ()

static int	weekDayOfJulian (qint64 jd)

static bool	leapTest (int year)

static int	monthLength (int month, int year)

static bool	validParts (int year, int month, int day)

static QCalendar::YearMonthDay	partsFromJulian (qint64 jd)

static std::optional< qint64 >	julianFromParts (int year, int month, int day)

static int	yearStartWeekDay (int year)

static int	yearSharingWeekDays (QDate date)

Static Public Member Functions inherited from QCalendarBackend
static QStringList	availableCalendars ()
	Returns a list of names of the available calendar systems.

Additional Inherited Members
Protected Member Functions inherited from QRomanCalendar
const QCalendarLocale *	localeMonthIndexData () const override

const char16_t *	localeMonthData () const override

Detailed Description

The QGregorianCalendar class implements the Gregorian calendar.

Since: 5.14

\inmodule QtCore

Definition at line 24 of file qgregoriancalendar_p.h.

Member Function Documentation

◆ dateToJulianDay()

bool QGregorianCalendar::dateToJulianDay	(	int	year,
		int	month,
		int	day,
		qint64 *	jd ) const

overridevirtual

Computes the Julian day number corresponding to the specified year, month, and day.

Returns true and sets jd if there is such a date in this calendar; otherwise, returns false.

See also: QCalendar::partsFromDate(), julianDayToDate()

Implements QCalendarBackend.

Definition at line 99 of file qgregoriancalendar.cpp.

References julianFromParts().

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◆ isLeapYear()

bool QGregorianCalendar::isLeapYear ( int year ) const

overridevirtual

Returns true if the specified year is a leap year for this calendar.

See also: daysInYear(), isDateValid()

Implements QCalendarBackend.

Definition at line 60 of file qgregoriancalendar.cpp.

References leapTest().

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◆ julianDayToDate()

QCalendar::YearMonthDay QGregorianCalendar::julianDayToDate ( qint64 jd ) const

overridevirtual

Computes the year, month, and day in this calendar for the given Julian day number jd.

If the given day falls outside this calendar's scope (e.g. before the start-date of a non-proleptic calendar), the returned structure's isValid() is false; otherwise, its year, month, and day fields provide this calendar's description of the date.

See also: QCalendar::dateFromParts(), dateToJulianDay()

Implements QCalendarBackend.

Definition at line 107 of file qgregoriancalendar.cpp.

References partsFromJulian().

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◆ julianFromParts()

std::optional< qint64 > QGregorianCalendar::julianFromParts	(	int	year,
		int	month,
		int	day )

static

Definition at line 234 of file qgregoriancalendar.cpp.

References BaseJd, validParts(), and QRomanCalendrical::yearMonthToYearDays().

Referenced by QDate::QDate(), QLocalTime::computeSystemMillisRange(), dateToJulianDay(), QDate::dayOfYear(), QDateTimePrivate::expressUtcAsLocal(), fixedDate(), matchCenturyToWeekday(), millisToWithinRange(), and QDate::setDate().

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◆ leapTest()

bool QGregorianCalendar::leapTest ( int year )

static

Definition at line 65 of file qgregoriancalendar.cpp.

References QCalendar::Unspecified.

Referenced by QDate::daysInYear(), QDate::isLeapYear(), isLeapYear(), monthLength(), systemTimeYearMatching(), and yearSharingWeekDays().

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◆ matchCenturyToWeekday()

qint64 QGregorianCalendar::matchCenturyToWeekday	(	const QCalendar::YearMonthDay &	parts,
		int	dow ) const

overridevirtual

Since: 6.7 Adjusts century of parts to match dow.

Preserves parts.month and parts.day while adjusting parts.year by a multiple of 100 (taking the absence of year zero into account, when relevant) to obtain a date for which dayOfWeek() is dow. Prefers smaller changes over larger and increases to the century over decreases of the same magnitude. Returns the Julian Day number for the selected date or std::numeric_limits<qint64>::min(), a.k.a. QDate::nullJd(), if there is no date matching these requirements.

The base-class provides a brute-force implementation that steps outwards from the given date by centures, above and below by up to 14 centuries, in search of a matching date. This is neither computationally efficient nor elegant but should work as advertised for calendars in which every month-day combination does appear on all days of the week, across sufficiently many centuries.

Reimplemented from QCalendarBackend.

Definition at line 113 of file qgregoriancalendar.cpp.

References QCalendar::YearMonthDay::day, julianFromParts(), QCalendar::YearMonthDay::month, Q_ASSERT, Qt::Tuesday, weekDayOfJulian(), and QCalendar::YearMonthDay::year.

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