CopperSpice API  1.7.4
QDateTime Class Reference

Provides date and time functions. More...

## Public Methods

QDateTime ()

QDateTime (const QDate &date)

QDateTime (const QDate &date, const QTime &time, const QTimeZone &timeZone)

QDateTime (const QDate &date, const QTime &time, Qt::TimeSpec spec=Qt::LocalTime, int offsetSeconds=0)

QDateTime (const QDateTime &other)

QDateTime (QDateTime &&other)

~QDateTime ()

QDateTime addDays (qint64 days) const

QDateTime addMonths (qint64 months) const

QDateTime addMSecs (qint64 msecs) const

QDateTime addSecs (qint64 secs) const

QDateTime addYears (qint64 years) const

QDate date () const

qint64 daysTo (const QDateTime &value) const

bool isDaylightTime () const

bool isNull () const

bool isValid () const

qint64 msecsTo (const QDateTime &value) const

int offsetFromUtc () const

bool operator!= (const QDateTime &value) const

bool operator< (const QDateTime &value) const

bool operator<= (const QDateTime &value) const

QDateTime & operator= (const QDateTime &other)

QDateTime & operator= (QDateTime &&other)

bool operator== (const QDateTime &value) const

bool operator> (const QDateTime &value) const

bool operator>= (const QDateTime &value) const

qint64 secsTo (const QDateTime &value) const

void setDate (const QDate &date)

void setMSecsSinceEpoch (qint64 msecs)

void setOffsetFromUtc (int offsetSeconds)

void setTime (const QTime &time)

void setTime_t (quint64 seconds)

void setTimeSpec (Qt::TimeSpec spec)

void setTimeZone (const QTimeZone &toZone)

void swap (QDateTime &other)

QTime time () const

Qt::TimeSpec timeSpec () const

QTimeZone timeZone () const

QString timeZoneAbbreviation () const

CFDateRef toCFDate () const

QDateTime toLocalTime () const

qint64 toMSecsSinceEpoch () const

NSDate * toNSDate () const

QDateTime toOffsetFromUtc (qint64 offsetSeconds) const

QString toString (const QString &format) const

QString toString (Qt::DateFormat format=Qt::TextDate) const

quint64 toTime_t () const

QDateTime toTimeSpec (Qt::TimeSpec specification) const

QDateTime toTimeZone (const QTimeZone &timeZone) const

QDateTime toUTC () const

## Static Public Methods

static QDateTime currentDateTime ()

static QDateTime currentDateTimeUtc ()

static qint64 currentMSecsSinceEpoch ()

static QDateTime fromCFDate (CFDateRef date)

static QDateTime fromMSecsSinceEpoch (qint64 msecs, const QTimeZone &timeZone)

static QDateTime fromMSecsSinceEpoch (qint64 msecs, Qt::TimeSpec spec=Qt::LocalTime, int offsetFromUtc=0)

static QDateTime fromNSDate (const NSDate *date)

static QDateTime fromString (const QString &str, const QString &format)

static QDateTime fromString (const QString &str, Qt::DateFormat format=Qt::TextDate)

static QDateTime fromTime_t (quint64 seconds, const QTimeZone &timeZone)

static QDateTime fromTime_t (quint64 seconds, Qt::TimeSpec spec=Qt::LocalTime, int offsetFromUtc=0)

## Friends

QDataStreamoperator<< (QDataStream &stream, const QDateTime &dateTime)

QDataStreamoperator>> (QDataStream &stream, QDateTime &dateTime)

## Detailed Description

The QDateTime class provides date and time functions.

A QDateTime object contains a calendar date and a clock time (a "datetime"). It is a combination of the QDate and QTime classes. It can read the current datetime from the system clock. It provides functions for comparing datetimes and for manipulating a datetime by adding a number of seconds, days, months, or years.

A QDateTime object is typically created either by giving a date and time explicitly in the constructor, or by using the static function currentDateTime() that returns a QDateTime object set to the system clock's time. The date and time can be changed with setDate() and setTime(). A datetime can also be set using the setTime_t() method which takes a POSIX-standard "number of seconds since 00:00:00 on January 1, 1970" value. The fromString() method returns a QDateTime, given a string and a date format used to interpret the date within the string.

The date() and time() methods provide access to the date and time parts of the datetime. The same information is provided in textual format by the toString() function.

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

You can increment (or decrement) a datetime by a given number of milliseconds using addMSecs(), seconds using addSecs(), or days using addDays(). Similarly you can use addMonths() and addYears(). The daysTo() function returns the number of days between two datetimes, secsTo() returns the number of seconds between two datetimes, and msecsTo() returns the number of milliseconds between two datetimes.

QDateTime can store datetimes as local time or as UTC. QDateTime::currentDateTime() returns a QDateTime expressed as local time, use toUTC() to convert it to UTC. You can also use timeSpec() to find out if a QDateTime object stores a UTC time or a local time. Operations such as addSecs() and secsTo() are aware of daylight saving time (DST).

Note
QDateTime does not account for leap seconds.

### Gregorian and Julian Calendars

QDate uses the Gregorian calendar in all locales, beginning on the date 15 October 1582. For dates up to and including 4 October 1582, the Julian calendar is used. This means there is a 10-day gap in the internal calendar between the 4th and the 15th of October 1582. When you use QDateTime for dates in that epoch, the day after 4 October 1582 is 15 October 1582, and the dates in the gap are invalid.

The Julian to Gregorian changeover date used here is the date when the Gregorian calendar was first introduced, by Pope Gregory XIII. That change was not universally accepted and some localities only executed it at a later date (if at all). QDateTime does not take any of these historical facts into account. If an application must support a locale-specific dating system, it must do so on its own, remembering to convert the dates using the Julian day.

### 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 0001-01-01 is December 31st, 1 BCE.

### Range of Valid Dates

The range of valid values able to be stored in QDateTime is dependent on the internal storage implementation. QDateTime is currently stored in a qint64 as a serial msecs value encoding the date and time. This restricts the date range to about +/- 292 million years, compared to the QDate range of +/- 2 billion years. Care must be taken when creating a QDateTime with extreme values that you do not overflow the storage. The exact range of supported values varies depending on the Qt::TimeSpec and time zone.

### Use of System Timezone

QDateTime uses the system's time zone information to determine the offset of local time from UTC. If the system is not configured correctly or not up-to-date, QDateTime will give wrong results as well.

### Daylight Saving Time (DST)

QDateTime takes into account the system's time zone information when dealing with DST. On modern Unix systems, this means it applies the correct historical DST data whenever possible. On Windows, where the system does not support historical DST data, historical accuracy is not maintained with respect to DST.

The range of valid dates taking DST into account is 1970-01-01 to the present, and rules are in place for handling DST correctly until 2037-12-31, but these could change. For dates falling outside that range, QDateTime makes a best guess using the rules for year 1970 or 2037, but we can not guarantee accuracy. This means QDateTime does not take into account changes in a locale's time zone before 1970, even if the system's time zone database supports that information.

QDateTime takes into consideration the Standard Time to Daylight-Saving Time transition. For example if the transition is at 2am and the clock goes forward to 3am, then there is a "missing" hour from 02:00:00 to 02:59:59.999 which QDateTime considers to be invalid. Any date maths performed will take this missing hour into account and return a valid result.

### Offset From UTC

A Qt::TimeSpec of Qt::OffsetFromUTC is also supported. This allows you to define a QDateTime relative to UTC at a fixed offset of a given number of seconds from UTC. For example, an offset of +3600 seconds is one hour ahead of UTC and is usually written in ISO standard notation as "UTC+01:00". Daylight-Saving Time never applies with this TimeSpec.

There is no explicit size restriction to the offset seconds, but there is an implicit limit imposed when using the toString() and fromString() methods which use a format of [+|-]hh:mm, effectively limiting the range to +/- 99 hours and 59 minutes and whole minutes only. Note that currently no time zone lies outside the range of +/- 14 hours.

### Time Zone Support

A Qt::TimeSpec of Qt::TimeZone is also supported in conjunction with the QTimeZone class. This allows you to define a datetime in a named time zone adhering to a consistent set of daylight-saving transition rules. For example a time zone of "Europe/Berlin" will apply the daylight-saving rules as used in Germany since 1970. Note that the transition rules applied depend on the platform support. See the QTimeZone documentation for more details.

See also
QDate, QTime, QDateTimeEdit, QTimeZone

## Constructor & Destructor Documentation

 QDateTime::QDateTime ( )

Constructs a null date and null time. A null datetime is invalid since the date is invalid.

See also
isValid()
 QDateTime::QDateTime ( const QDate & date )
explicit

Constructs a QDateTime with the given date and a valid time of 00:00:00.000. Sets the timeSpec() to Qt::LocalTime.

 QDateTime::QDateTime ( const QDate & date, const QTime & time, Qt::TimeSpec spec = Qt::LocalTime, int offsetSeconds = 0 )

Constructs a datetime with the given date and time using the time specification defined by spec and offsetSeconds seconds.

• If date is valid and time is not, the time will be set to midnight.
• If the spec is not Qt::OffsetFromUTC then offsetSeconds will be ignored.
• If the spec is Qt::OffsetFromUTC and offsetSeconds is 0 then the timeSpec() will be set to Qt::UTC, which is an offset of 0 seconds.
• If spec is Qt::TimeZone then the spec will be set to Qt::LocaleTime which is the current system time zone.
• To create a QDateTime with a Qt::TimeZone, a different constructor must be used.
 QDateTime::QDateTime ( const QDate & date, const QTime & time, const QTimeZone & timeZone )

Constructs a datetime with the given date and time using the Time Zone specified by timeZone. If date is valid and time is not the time will be set to midnight. If timeZone is invalid than the datetime will be invalid.

 QDateTime::QDateTime ( const QDateTime & other )

Copy constructs a new QDateTime from other.

 QDateTime::QDateTime ( QDateTime && other )

Move constructs a new QDateTime from other.

 QDateTime::~QDateTime ( )

Destroys the datetime.

## Method Documentation

 QDateTime QDateTime::addDays ( qint64 days ) const
nodiscard

Returns a QDateTime object containing a datetime days days later than the datetime of this object (or earlier if days is negative).

See also
daysTo(), addMonths(), addYears(), addSecs()
 QDateTime QDateTime::addMonths ( qint64 months ) const
nodiscard

Returns a QDateTime object containing a datetime months months later than the datetime of this object (or earlier if nmonths is negative).

See also
daysTo(), addDays(), addYears(), addSecs()
 QDateTime QDateTime::addMSecs ( qint64 msecs ) const
nodiscard

Returns a QDateTime object containing a datetime msecs milliseconds later than the datetime of this object (or earlier if msecs is negative).

See also
addSecs(), msecsTo(), addDays(), addMonths(), addYears()
 QDateTime QDateTime::addSecs ( qint64 secs ) const
nodiscard

Returns a QDateTime object containing a datetime secs seconds later than the datetime of this object (or earlier if s is negative).

See also
addMSecs(), secsTo(), addDays(), addMonths(), addYears()
 QDateTime QDateTime::addYears ( qint64 years ) const
nodiscard

Returns a QDateTime object containing a datetime years years later than the datetime of this object (or earlier if nyears is negative).

See also
daysTo(), addDays(), addMonths(), addSecs()
 QDateTime QDateTime::currentDateTime ( )
static

Returns the current datetime, as reported by the system clock, in the local time zone.

See also
currentDateTimeUtc(), QDate::currentDate(), QTime::currentTime(), toTimeSpec()
 QDateTime QDateTime::currentDateTimeUtc ( )
static

Returns the current datetime, as reported by the system clock, in UTC.

See also
currentDateTime(), QDate::currentDate(), QTime::currentTime(), toTimeSpec()
 qint64 QDateTime::currentMSecsSinceEpoch ( )
static

Returns the number of milliseconds since 1970-01-01T00:00:00 Universal Coordinated Time. This number is like the POSIX time_t variable, but expressed in milliseconds instead.

See also
currentDateTime(), currentDateTimeUtc(), toTime_t(), toTimeSpec()
 QDate QDateTime::date ( ) const

Returns the date part of the datetime.

See also
setDate(), time(), timeSpec()
 qint64 QDateTime::daysTo ( const QDateTime & value ) const

Returns the number of days from this datetime to the value datetime. If the other datetime is earlier than this datetime, the value returned is negative.

See also
addDays(), secsTo(), msecsTo()
 QDateTime QDateTime::fromCFDate ( CFDateRef date )
static

Constructs a new QDateTime containing a copy of the CFDate date.

See also
toCFDate()
 QDateTime QDateTime::fromMSecsSinceEpoch ( qint64 msecs, const QTimeZone & timeZone )
static

Returns a datetime whose date and time are the number of milliseconds, msecs, that have passed since 1970-01-01T00:00:00.000, Coordinated Universal Time (Qt::UTC) and with the given timeZone.

See also
fromTime_t()
 QDateTime QDateTime::fromMSecsSinceEpoch ( qint64 msecs, Qt::TimeSpec spec = Qt::LocalTime, int offsetFromUtc = 0 )
static

Returns a datetime whose date and time are the number of milliseconds msecs that have passed since 1970-01-01T00:00:00.000, Coordinated Universal Time (Qt::UTC) and converted to the given spec.

If the spec is not Qt::OffsetFromUTC then the offsetFromUtc will be ignored. If the spec is Qt::OffsetFromUTC and the offsetSeconds is 0 then the spec will be set to Qt::UTC, i.e. an offset of 0 seconds.

See also
fromTime_t()
 QDateTime QDateTime::fromNSDate ( const NSDate * date )
static

Constructs a new QDateTime containing a copy of the NSDate date.

See also
toNSDate()
 QDateTime QDateTime::fromString ( const QString & str, const QString & format )
static

Returns the QDateTime represented by the str, using the format given, or an invalid datetime if the string can not be parsed.

These expressions may be used for the date part of the format string:

ExpressionOutput
dthe day as number without a leading zero (1 to 31)
ddthe day as number with a leading zero (01 to 31)
dddthe abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses QDate::shortDayName().
ddddthe long localized day name (e.g. 'Monday' to 'Sunday'). Uses QDate::longDayName().
Mthe month as number without a leading zero (1-12)
MMthe month as number with a leading zero (01-12)
MMMthe abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses QDate::shortMonthName().
MMMMthe long localized month name (e.g. 'January' to 'December'). Uses QDate::longMonthName().
yythe year as two digit number (00-99)
yyyythe year as four digit number
Note
Unlike the other version of this function, day and month names must be given in the user's local language. It is only possible to use the English names if the user's language is English.

These expressions may be used for the time part of the format string:

ExpressionOutput
hthe hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
hhthe hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
Hthe hour without a leading zero (0 to 23, even with AM/PM display)
HHthe hour with a leading zero (00 to 23, even with AM/PM display)
mthe minute without a leading zero (0 to 59)
mmthe minute with a leading zero (00 to 59)
sthe second without a leading zero (0 to 59)
ssthe second with a leading zero (00 to 59)
zthe milliseconds without leading zeroes (0 to 999)
zzzthe milliseconds with leading zeroes (000 to 999)
AP or Ainterpret as an AM/PM time. AP must be either "AM" or "PM".
ap or aInterpret as an AM/PM time. ap must be either "am" or "pm".

All other input characters will be treated as text. Any sequence of characters that are enclosed in singlequotes will also be treated as text and not be used as an expression.

QTime time1 = QTime::fromString("131", "HHh");
// time1 is 13:00:00
QTime time2 = QTime::fromString("1apA", "1amAM");
// time2 is 01:00:00
QDateTime dateTime = QDateTime::fromString("M1d1y9800:01:02", "'M'M'd'd'y'yyhh:mm:ss");
// dateTime is 1 January 1998 00:01:02

If the format is not satisfied an invalid QDateTime is returned. The expressions that do not have leading zeroes (d, M, h, m, s, z) will be greedy. This means that they will use two digits even if this will put them outside the range and/or leave too few digits for other sections.

QDateTime dateTime = QDateTime::fromString("130", "Mm"); // invalid

This could have meant 1 January 00:30.00 but the M will grab two digits.

For any field that is not represented in the format the following defaults are used:

FieldDefault value
Year1900
Month1 (January)
Day1
Hour0
Minute0
Second0
QDateTime dateTime = QDateTime::fromString("1.30.1", "M.d.s");
// dateTime is January 30 in 1900 at 00:00:01.
See also
QDate::fromString(), QTime::fromString(), QDate::toString()
 QDateTime QDateTime::fromString ( const QString & str, Qt::DateFormat format = Qt::TextDate )
static

Returns the QDateTime represented by the str, using the format given, or an invalid datetime if this is not possible.

For Qt::TextDate it is recommended you use the English short month names (for example, "Jan"). Although localized month names can also be used, they depend on the user's locale settings.

 QDateTime QDateTime::fromTime_t ( quint64 seconds, const QTimeZone & timeZone )
static

Returns a datetime whose date and time are the number of seconds that have passed since 1970-01-01T00:00:00, Coordinated Universal Time (Qt::UTC) and with the given timeZone.

See also
toTime_t(), setTime_t()
 QDateTime QDateTime::fromTime_t ( quint64 seconds, Qt::TimeSpec spec = Qt::LocalTime, int offsetFromUtc = 0 )
static

Returns a datetime whose date and time are the number of seconds that have passed since 1970-01-01T00:00:00, Coordinated Universal Time (Qt::UTC) and converted to the given spec.

If the spec is not Qt::OffsetFromUTC then the offsetSeconds will be ignored. If the spec is Qt::OffsetFromUTC and the offsetSeconds is 0 then the spec will be set to Qt::UTC, which is an offset of 0 seconds.

See also
toTime_t(), setTime_t()
 bool QDateTime::isDaylightTime ( ) const

Returns if this datetime falls in Daylight-Saving Time. If the Qt::TimeSpec is not Qt::LocalTime or Qt::TimeZone then will always return false.

See also
timeSpec()
 bool QDateTime::isNull ( ) const

Returns true if both the date and the time are null, otherwise returns false. A null datetime is invalid.

See also
QDate::isNull(), QTime::isNull(), isValid()
 bool QDateTime::isValid ( ) const

Returns true if both the date and the time are valid, otherwise returns false.

See also
QDate::isValid(), QTime::isValid()
 qint64 QDateTime::msecsTo ( const QDateTime & value ) const

Returns the number of milliseconds from this datetime to the value datetime. If the other datetime is earlier than this datetime, the value returned is negative.

Before performing the comparison, the two datetimes are converted to Qt::UTC to ensure that the result is correct if one of the two datetimes has daylight saving time (DST) and the other does not.

See also
addMSecs(), daysTo(), QTime::msecsTo()
 int QDateTime::offsetFromUtc ( ) const

Returns the current Offset From UTC in seconds. If the timeSpec() is Qt::OffsetFromUTC this will be the value originally set.

If the timeSpec() is Qt::LocalTime this will be the difference between the Local Time and UTC including any Daylight Saving Offset.

If the timeSpec() is Qt::UTC this will be 0.

See also
setOffsetFromUtc()
 bool QDateTime::operator!= ( const QDateTime & value ) const
inline

Returns true if this datetime is different from the value datetime, otherwise returns false.

Two datetimes are different if either the date, the time, or the time zone components are different.

See also
operator==()
 bool QDateTime::operator< ( const QDateTime & value ) const

Returns true if this datetime is earlier than the value datetime, otherwise returns false.

 bool QDateTime::operator<= ( const QDateTime & value ) const
inline

Returns true if this datetime is earlier than or equal to the value datetime, otherwise returns false.

 QDateTime & QDateTime::operator= ( const QDateTime & other )

Copy assigns from other and returns a reference to this object.

 QDateTime & QDateTime::operator= ( QDateTime && other )
inline

Move assigns from other and returns a reference to this object.

 bool QDateTime::operator== ( const QDateTime & value ) const

Returns true if this datetime is equal to the value datetime, otherwise returns false.

See also
operator!=()
 bool QDateTime::operator> ( const QDateTime & value ) const
inline

Returns true if this datetime is later than the value datetime, otherwise returns false.

 bool QDateTime::operator>= ( const QDateTime & value ) const
inline

Returns true if this datetime is later than or equal to the value datetime, otherwise returns false.

 qint64 QDateTime::secsTo ( const QDateTime & value ) const

Returns the number of seconds from this datetime to the value datetime. If the other datetime is earlier than this datetime, the value returned is negative.

Before performing the comparison, the two datetimes are converted to Qt::UTC to ensure that the result is correct if one of the two datetimes has daylight saving time (DST) and the other does not.

QDateTime xmas(QDate(now.date().year(), 12, 25), QTime(0, 0));
qDebug("There are %d seconds to Christmas", now.secsTo(xmas));
See also
addSecs(), daysTo(), QTime::secsTo()
 void QDateTime::setDate ( const QDate & date )

Sets the date part of this datetime to date. If no time is set, it is set to midnight.

See also
date(), setTime(), setTimeSpec()
 void QDateTime::setMSecsSinceEpoch ( qint64 msecs )

Sets the date and time given the number of milliseconds, msecs, that have passed since 1970-01-01T00:00:00.000, Coordinated Universal Time (Qt::UTC). On systems that do not support time zones this function will behave as if local time were Qt::UTC.

Note that there are possible values for msecs that lie outside the valid range of QDateTime, both negative and positive. The behavior of this function is undefined for those values.

See also
toMSecsSinceEpoch(), setTime_t()
 void QDateTime::setOffsetFromUtc ( int offsetSeconds )

Sets the timeSpec() to Qt::OffsetFromUTC and the offset to offsetSeconds. The datetime will refer to a different point in time.

The maximum and minimum offset is 14 positive or negative hours. If offsetSeconds is larger or smaller than that, then the result is undefined. If offsetSeconds is 0 then the timeSpec() will be set to Qt::UTC.

See also
isValid(), offsetFromUtc()
 void QDateTime::setTime ( const QTime & time )

Sets the time part of this datetime to time.

See also
time(), setDate(), setTimeSpec()
 void QDateTime::setTime_t ( quint64 seconds )

Sets the date and time given the number of seconds that have passed since 1970-01-01T00:00:00, Coordinated Universal Time (Qt::UTC). On systems that do not support time zones this function will behave as if local time were Qt::UTC.

See also
toTime_t()
 void QDateTime::setTimeSpec ( Qt::TimeSpec spec )

Sets the time specification used in this datetime to spec.

See also
timeSpec(), setDate(), setTime(), Qt::TimeSpec
 void QDateTime::setTimeZone ( const QTimeZone & toZone )

Sets the time zone used in this datetime to toZone. The datetime will refer to a different point in time. If toZone is invalid then the datetime will be invalid.

See also
timeZone(), Qt::TimeSpec
 void QDateTime::swap ( QDateTime & other )
inline

Swaps other with this object. This operation is very fast and never fails.

 QTime QDateTime::time ( ) const

Returns the time part of the datetime.

See also
setTime(), date(), timeSpec()
 Qt::TimeSpec QDateTime::timeSpec ( ) const

Returns the time specification of the datetime.

See also
setTimeSpec(), date(), time(), Qt::TimeSpec
 QTimeZone QDateTime::timeZone ( ) const

Returns the time zone of the datetime.

If the timeSpec() is Qt::LocalTime then an instance of the current system time zone will be returned. Note however that if you copy this time zone the instance will not remain in sync if the system time zone changes.

See also
setTimeZone(), Qt::TimeSpec
 QString QDateTime::timeZoneAbbreviation ( ) const

Returns the Time Zone Abbreviation for the datetime.

If the timeSpec() is Qt::UTC this will be "UTC". If the timeSpec() is Qt::OffsetFromUTC and the offset is not zero, this will be in the format "UTC[+-]00:00". If the timeSpec() is Qt::LocalTime then the host system is queried for the correct abbreviation.

Abbreviations may or may not be localized and they are not guaranteed to be a unique value. For example, different time zones may have the same abbreviation.

See also
timeSpec(), Qt::TimeSpec
 CFDateRef QDateTime::toCFDate ( ) const

Creates a CFDate from a QDateTime. The caller owns the CFDate object and is responsible for releasing it.

See also
fromCFDate()
 QDateTime QDateTime::toLocalTime ( ) const
inline

Returns a datetime containing the date and time information in this datetime, but specified using the Qt::LocalTime definition.

See also
toTimeSpec()
 qint64 QDateTime::toMSecsSinceEpoch ( ) const

Returns the datetime as the number of milliseconds that have passed since 1970-01-01T00:00:00.000, Coordinated Universal Time (Qt::UTC). On systems that do not support time zones, this function will behave as if local time were Qt::UTC.

The behavior for this function is undefined if the datetime stored in this object is not valid. However, for all valid dates, this function returns a unique value.

See also
toTime_t(), setMSecsSinceEpoch()
 NSDate * QDateTime::toNSDate ( ) const

Creates an NSDate from a QDateTime. The NSDate object is autoreleased.

See also
fromNSDate()
 QDateTime QDateTime::toOffsetFromUtc ( qint64 offsetSeconds ) const

Returns a copy of this datetime converted to a spec of Qt::OffsetFromUTC with the given offsetSeconds. If the offsetSeconds equals 0 then a UTC datetime will be returned.

See also
setOffsetFromUtc(), offsetFromUtc(), toTimeSpec()
 QString QDateTime::toString ( const QString & format ) const

Returns the datetime as a string. The format parameter determines the format of the result string.

These expressions may be used for the date:

ExpressionOutput
dthe day as number without a leading zero (1 to 31)
ddthe day as number with a leading zero (01 to 31)
dddthe abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses QDate::shortDayName().
ddddthe long localized day name (e.g. 'Monday' to 'Sunday'). Uses QDate::longDayName().
Mthe month as number without a leading zero (1-12)
MMthe month as number with a leading zero (01-12)
MMMthe abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses QDate::shortMonthName().
MMMMthe long localized month name (e.g. 'January' to 'December'). Uses QDate::longMonthName().
yythe year as two digit number (00-99)
yyyythe year as four digit number

These expressions may be used for the time:

ExpressionOutput
hthe hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
hhthe hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
mthe minute without a leading zero (0 to 59)
mmthe minute with a leading zero (00 to 59)
sthe second without a leading zero (0 to 59)
ssthe second with a leading zero (00 to 59)
zthe milliseconds without leading zeroes (0 to 999)
zzzthe milliseconds with leading zeroes (000 to 999)
APuse AM/PM display. AP will be replaced by either "AM" or "PM".
apuse am/pm display. ap will be replaced by either "am" or "pm".

All other input characters will be ignored. Any sequence of characters that are enclosed in singlequotes will be treated as text and not be used as an expression. Two consecutive singlequotes ("''") are replaced by a singlequote in the output.

Example format strings (assumed that the QDateTime is 21 May 2001 14:13:09):

FormatResult
dd.MM.yyyy21.05.2001
ddd MMMM d yyTue May 21 01
hh:mm:ss.zzz14:13:09.042
h:m:s ap2:13:9 pm

If the datetime is invalid, an empty string will be returned.

See also
QDate::toString(), QTime::toString()
 QString QDateTime::toString ( Qt::DateFormat format = Qt::TextDate ) const

Returns the datetime as a string in the format given.

If the format is Qt::TextDate, the string is formatted in the default way. QDate::shortDayName(), QDate::shortMonthName(), and QTime::toString() are used to generate the string, so the day and month names will be localized names. An example of this formatting is "Wed March 14 03:40:13 2011".

If the format is Qt::ISODate the string format corresponds to the ISO 8601 extended specification for representations of dates and times. It will use the form YYYY-MM-DDTHH:mm:ss[Z|[+|-]HH:mm], depending on the timeSpec() of the QDateTime. If the timeSpec() is Qt::UTC, Z will be appended to the string. If the timeSpec() is Qt::OffsetFromUTC the offset in hours and minutes from UTC will be appended to the string.

If the format is Qt::SystemLocaleShortDate or Qt::SystemLocaleLongDate, the string format depends on the locale settings of the system. Identical to calling QLocale::system().toString(datetime, QLocale::ShortFormat) or QLocale::system().toString(datetime, QLocale::LongFormat).

If the format is Qt::DefaultLocaleShortDate or Qt::DefaultLocaleLongDate, the string format depends on the default application locale. This is the locale set with QLocale::setDefault(), or the system locale if no default locale has been set. Identical to calling QLocale().toString(datetime, QLocale::ShortFormat) or QLocale().toString(datetime, QLocale::LongFormat).

If the datetime is invalid an empty string will be returned.

Warning
The Qt::ISODate format is only valid for years in the range 0 to 9999. This restriction may apply to locale-aware formats as well, depending on the locale settings.
See also
QDate::toString(), QTime::toString(), Qt::DateFormat
 quint64 QDateTime::toTime_t ( ) const

Returns the datetime as the number of seconds that have passed since 1970-01-01T00:00:00, Coordinated Universal Time (Qt::UTC).

On systems that do not support time zones, this function will behave as if local time were Qt::UTC.

Note
This function returns a 32-bit unsigned integer, so it does not support dates before 1970, but it does support dates after 2038-01-19T03:14:06, which may not be valid time_t values. Be careful when passing those time_t values to system functions, which could interpret them as negative dates.

If the date is outside the range 1970-01-01T00:00:00 to 2106-02-07T06:28:14, this function returns -1 cast to an unsigned integer (i.e., 0xFFFFFFFF).

To get an extended range use toMSecsSinceEpoch().

See also
toMSecsSinceEpoch(), setTime_t()
 QDateTime QDateTime::toTimeSpec ( Qt::TimeSpec specification ) const

Returns a copy of this datetime configured to use the given time specification.

See also
timeSpec(), toUTC(), toLocalTime()
 QDateTime QDateTime::toTimeZone ( const QTimeZone & timeZone ) const

Returns a copy of this datetime converted to the given timeZone.

See also
timeZone(), toTimeSpec()
 QDateTime QDateTime::toUTC ( ) const
inline

Returns a datetime containing the date and time information in this datetime, but specified using the Qt::UTC definition.

See also
toTimeSpec()

## Friends And Related Function Documentation

 QDataStream & operator<< ( QDataStream & stream, const QDateTime & dateTime )
friend

Writes the given dateTime to the stream. Returns a reference to the stream.

Refer to Serializing Data Types for additional information.

 QDataStream & operator>> ( QDataStream & stream, QDateTime & dateTime )
friend

Reads from the stream into the given dateTime. Returns a reference to the stream.

Refer to Serializing Data Types for additional information.