Qt QDate

Public Functions

 

	QDate()
	QDate(int y, int m, int d)
QDate	addDays(qint64 ndays) const
QDate	addMonths(int nmonths) const
QDate	addYears(int nyears) const
int	day() const
int	dayOfWeek() const
int	dayOfYear() const
int	daysInMonth() const
int	daysInYear() const
qint64	daysTo(const QDate &d) const
void	getDate(int *year, int *month, int *day) const
bool	isNull() const
bool	isValid() const
int	month() const
bool	setDate(int year, int month, int day)
qint64	toJulianDay() const
QString	toString(const QString &format) const
QString	toString(Qt::DateFormat format = Qt::TextDate) const
int	weekNumber(int *yearNumber = Q_NULLPTR) const
int	year() const
bool	operator!=(const QDate &d) const
bool	operator<(const QDate &d) const
bool	operator<=(const QDate &d) const
bool	operator==(const QDate &d) const
bool	operator>(const QDate &d) const
bool	operator>=(const QDate &d) const

Static Public Members

 

QDate	currentDate()
QDate	fromJulianDay(qint64 jd)
QDate	fromString(const QString &string, Qt::DateFormat format = Qt::TextDate)
QDate	fromString(const QString &string, const QString &format)
bool	isLeapYear(int year)
bool	isValid(int year, int month, int day)
QString	longDayName(int weekday, MonthNameType type = DateFormat)
QString	longMonthName(int month, MonthNameType type = DateFormat)
QString	shortDayName(int weekday, MonthNameType type = DateFormat)
QString	shortMonthName(int month, MonthNameType type = DateFormat)

Related Non-Members

 

QDataStream &	operator<<(QDataStream &out, const QDate &date)
QDataStream &	operator>>(QDataStream &in, QDate &date)

 

Detailed Description

The QDate class provides date functions.

A QDate object contains a calendar date, i.e. year, month, and day numbers, in the Gregorian calendar. It can read the current date from the system clock. It provides functions for comparing dates, and for manipulating dates. For example, it is possible to add and subtract days, months, and years to dates.

A QDate object is typically created by giving the year, month, and day numbers explicitly. Note that QDate interprets two digit years as is, i.e., years 0 - 99. A QDate can also be constructed with the static function currentDate(), which creates a QDate object containing the system clock's date. An explicit date can also be set using setDate(). The fromString() function returns a QDate given a string and a date format which is used to interpret the date within the string.

The year(), month(), and day() functions provide access to the year, month, and day numbers. Also, dayOfWeek() and dayOfYear() functions are provided. The same information is provided in textual format by the toString(), shortDayName(), longDayName(), shortMonthName(), and longMonthName() functions.

QDate provides a full set of operators to compare two QDate objects where smaller means earlier, and larger means later.

You can increment (or decrement) a date by a given number of days using addDays(). Similarly you can use addMonths() and addYears(). The daysTo() function returns the number of days between two dates.

The daysInMonth() and daysInYear() functions return how many days there are in this date's month and year, respectively. The isLeapYear() function indicates whether a date is in a leap year.

No Year 0

There is no year 0. Dates in that year are considered invalid. The year -1 is the year "1 before Christ" or "1 before current era." The day before 1 January 1 CE is 31 December 1 BCE.

Range of Valid Dates

Dates are stored internally as a Julian Day number, an integer count of every day in a contiguous range, with 24 November 4714 BCE in the Gregorian calendar being Julian Day 0 (1 January 4713 BCE in the Julian calendar). As well as being an efficient and accurate way of storing an absolute date, it is suitable for converting a Date into other calendar systems such as Hebrew, Islamic or Chinese. The Julian Day number can be obtained using QDate::toJulianDay() and can be set using QDate::fromJulianDay().

The range of dates able to be stored by QDate as a Julian Day number is for technical reasons limited to between -784350574879 and 784354017364, which means from before 2 billion BCE to after 2 billion CE.