\inmodule QtCore More...

#include <qvariant.h>

Collaboration diagram for QVariant:

Classes
class	ConstPointer
	QVariant::ConstPointer is a template class that emulates a const pointer to QVariant. More...
class	ConstReference
	The QVariant::ConstReference acts as a const reference to a QVariant. More...
class	Pointer
	QVariant::Pointer is a template class that emulates a non-const pointer to QVariant. More...
struct	Private
struct	PrivateShared
class	Reference
	The QVariant::Reference acts as a non-const reference to a QVariant. More...

Public Types
typedef Private	DataPtr

Public Member Functions
	QVariant () noexcept
	Constructs an invalid variant.
	~QVariant ()
	Destroys the QVariant and the contained object.
	QVariant (QMetaType type, const void *copy=nullptr)
	Constructs a variant of type type, and initializes it with a copy of {copy} if copy* is not \nullptr (in which case, copy must point to an object of type type).
	QVariant (const QVariant &other)
	Constructs a copy of the variant, p, passed as the argument to this constructor.
template<typename T, typename... Args, if_constructible< T, Args... > = true>
	QVariant (std::in_place_type_t< T >, Args &&... args) noexcept(is_noexcept_constructible< q20::remove_cvref_t< T >, Args... >::value)
template<typename T, typename U, typename... Args, if_constructible< T, std::initializer_list< U > &, Args... > = true>
	QVariant (std::in_place_type_t< T >, std::initializer_list< U > il, Args &&... args) noexcept(is_noexcept_constructible< q20::remove_cvref_t< T >, std::initializer_list< U > &, Args... >::value)
	QVariant (int i) noexcept
	Constructs a new variant with an integer value, val.
	QVariant (uint ui) noexcept
	Constructs a new variant with an unsigned integer value, val.
	QVariant (qlonglong ll) noexcept
	Constructs a new variant with a long long integer value, val.
	QVariant (qulonglong ull) noexcept
	Constructs a new variant with an unsigned long long integer value, val.
	QVariant (bool b) noexcept
	Constructs a new variant with a boolean value, val.
	QVariant (double d) noexcept
	Constructs a new variant with a floating point value, val.
	QVariant (float f) noexcept
	Constructs a new variant with a floating point value, val.
	QVariant (QChar qchar) noexcept
	Constructs a new variant with a char value, c.
	QVariant (QDate date) noexcept
	Constructs a new variant with a date value, val.
	QVariant (QTime time) noexcept
	Constructs a new variant with a time value, val.
	QVariant (const QBitArray &bitarray) noexcept
	Constructs a new variant with a bitarray value, val.
	QVariant (const QByteArray &bytearray) noexcept
	Constructs a new variant with a bytearray value, val.
	QVariant (const QDateTime &datetime) noexcept
	Constructs a new variant with a date/time value, val.
	QVariant (const QHash< QString, QVariant > &hash) noexcept
	Constructs a new variant with a hash of \l {QVariant}s, val.
	QVariant (const QJsonArray &jsonArray) noexcept
	QVariant (const QJsonObject &jsonObject) noexcept
	QVariant (const QList< QVariant > &list) noexcept
	Constructs a new variant with a list value, val.
	QVariant (const QLocale &locale) noexcept
	Constructs a new variant with a locale value, l.
	QVariant (const QMap< QString, QVariant > &map) noexcept
	Constructs a new variant with a map of \l {QVariant}s, val.
	QVariant (const QRegularExpression &re) noexcept
	QVariant (const QString &string) noexcept
	Constructs a new variant with a string value, val.
	QVariant (const QStringList &stringlist) noexcept
	Constructs a new variant with a string list value, val.
	QVariant (const QUrl &url) noexcept
	Constructs a new variant with a url value of val.
	QVariant (const QJsonValue &jsonValue) noexcept(Private::FitsInInternalSize< sizeof(CborValueStandIn)>)
	QVariant (const QModelIndex &modelIndex) noexcept(Private::FitsInInternalSize< 8+2 *sizeof(quintptr)>)
	QVariant (QUuid uuid) noexcept(Private::FitsInInternalSize< 16 >)
	QVariant (QSize size) noexcept
	Constructs a new variant with a size value of val.
	QVariant (QSizeF size) noexcept(Private::FitsInInternalSize< sizeof(qreal) *2 >)
	Constructs a new variant with a size value of val.
	QVariant (QPoint pt) noexcept
	Constructs a new variant with a point value of val.
	QVariant (QPointF pt) noexcept(Private::FitsInInternalSize< sizeof(qreal) *2 >)
	Constructs a new variant with a point value of val.
	QVariant (QLine line) noexcept(Private::FitsInInternalSize< sizeof(int) *4 >)
	Constructs a new variant with a line value of val.
	QVariant (QLineF line) noexcept(Private::FitsInInternalSize< sizeof(qreal) *4 >)
	Constructs a new variant with a line value of val.
	QVariant (QRect rect) noexcept(Private::FitsInInternalSize< sizeof(int) *4 >)
	Constructs a new variant with a rect value of val.
	QVariant (QRectF rect) noexcept(Private::FitsInInternalSize< sizeof(qreal) *4 >)
	Constructs a new variant with a rect value of val.
	QVariant (const QEasingCurve &easing) noexcept(false)
	QVariant (const QJsonDocument &jsonDocument) noexcept(false)
	QVariant (const QPersistentModelIndex &modelIndex) noexcept(false)
QT_ASCII_CAST_WARN	QVariant (const char *str) noexcept(false)
	Constructs a new variant with a string value of val.
	QVariant (QLatin1StringView string) noexcept(false)
	Constructs a new variant with a QString value from the Latin-1 string viewed by val.
template<typename T, std::enable_if_t< std::disjunction_v< std::is_pointer< T >, std::is_member_pointer< T > >, bool > = false>
	QVariant (T)=delete
QVariant &	operator= (const QVariant &other)
	Move-assigns other to this QVariant instance.
	QVariant (QVariant &&other) noexcept
	Move-constructs a QVariant instance, making it point at the same object that other was pointing to.
void	swap (QVariant &other) noexcept
int	userType () const
int	typeId () const
	Returns the storage type of the value stored in the variant.
const char *	typeName () const
	Returns the name of the type stored in the variant.
QMetaType	metaType () const
bool	canConvert (QMetaType targetType) const
bool	convert (QMetaType type)
	Casts the variant to the requested type, targetType.
bool	canView (QMetaType targetType) const
bool	isValid () const
	Returns `true` if the storage type of this variant is not QMetaType::UnknownType; otherwise returns `false`.
bool	isNull () const
	Returns `true` if this is a null variant, false otherwise.
void	clear ()
	Convert this variant to type QMetaType::UnknownType and free up any resources used.
void	detach ()
bool	isDetached () const
int	toInt (bool *ok=nullptr) const
	Returns the variant as an int if the variant has userType() \l QMetaType::Int, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.
uint	toUInt (bool *ok=nullptr) const
	Returns the variant as an unsigned int if the variant has userType() \l QMetaType::UInt, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, or \l QMetaType::ULongLong; otherwise returns 0.
qlonglong	toLongLong (bool *ok=nullptr) const
	Returns the variant as a long long int if the variant has userType() \l QMetaType::LongLong, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.
qulonglong	toULongLong (bool *ok=nullptr) const
	Returns the variant as an unsigned long long int if the variant has metaType() \l QMetaType::ULongLong, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, or \l QMetaType::UInt; otherwise returns 0.
bool	toBool () const
	Returns the variant as a bool if the variant has userType() Bool.
double	toDouble (bool *ok=nullptr) const
	Returns the variant as a double if the variant has userType() \l QMetaType::Double, \l QMetaType::Float, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.0.
float	toFloat (bool *ok=nullptr) const
	Returns the variant as a float if the variant has userType() \l QMetaType::Double, \l QMetaType::Float, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.0.
qreal	toReal (bool *ok=nullptr) const
	Returns the variant as a qreal if the variant has userType() \l QMetaType::Double, \l QMetaType::Float, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.0.
QByteArray	toByteArray () const
	Returns the variant as a QByteArray if the variant has userType() \l QMetaType::QByteArray or \l QMetaType::QString (converted using QString::fromUtf8()); otherwise returns an empty byte array.
QBitArray	toBitArray () const
	Returns the variant as a QBitArray if the variant has userType() \l QMetaType::QBitArray; otherwise returns an empty bit array.
QString	toString () const
	Returns the variant as a QString if the variant has a userType() including, but not limited to:
QStringList	toStringList () const
	Returns the variant as a QStringList if the variant has userType() \l QMetaType::QStringList, \l QMetaType::QString, or \l QMetaType::QVariantList of a type that can be converted to QString; otherwise returns an empty list.
QChar	toChar () const
	Returns the variant as a QChar if the variant has userType() \l QMetaType::QChar, \l QMetaType::Int, or \l QMetaType::UInt; otherwise returns an invalid QChar.
QDate	toDate () const
	Returns the variant as a QDate if the variant has userType() \l QMetaType::QDate, \l QMetaType::QDateTime, or \l QMetaType::QString; otherwise returns an invalid date.
QTime	toTime () const
	Returns the variant as a QTime if the variant has userType() \l QMetaType::QTime, \l QMetaType::QDateTime, or \l QMetaType::QString; otherwise returns an invalid time.
QDateTime	toDateTime () const
	Returns the variant as a QDateTime if the variant has userType() \l QMetaType::QDateTime, \l QMetaType::QDate, or \l QMetaType::QString; otherwise returns an invalid date/time.
QList< QVariant >	toList () const
	Returns the variant as a QVariantList if the variant has userType() \l QMetaType::QVariantList.
QMap< QString, QVariant >	toMap () const
	Returns the variant as a QVariantMap if the variant has metaType() \l QMetaType::QVariantMap.
QHash< QString, QVariant >	toHash () const
	Returns the variant as a QHash<QString, QVariant> if the variant has metaType() \l QMetaType::QVariantHash; otherwise returns an empty map.
QPoint	toPoint () const
	Returns the variant as a QPoint if the variant has userType() \l QMetaType::QPoint or \l QMetaType::QPointF; otherwise returns a null QPoint.
QPointF	toPointF () const
	Returns the variant as a QPointF if the variant has userType() \l QMetaType::QPoint or \l QMetaType::QPointF; otherwise returns a null QPointF.
QRect	toRect () const
	Returns the variant as a QRect if the variant has userType() \l QMetaType::QRect; otherwise returns an invalid QRect.
QSize	toSize () const
	Returns the variant as a QSize if the variant has userType() \l QMetaType::QSize; otherwise returns an invalid QSize.
QSizeF	toSizeF () const
	Returns the variant as a QSizeF if the variant has userType() \l QMetaType::QSizeF; otherwise returns an invalid QSizeF.
QLine	toLine () const
	Returns the variant as a QLine if the variant has userType() \l QMetaType::QLine; otherwise returns an invalid QLine.
QLineF	toLineF () const
	Returns the variant as a QLineF if the variant has userType() \l QMetaType::QLineF; otherwise returns an invalid QLineF.
QRectF	toRectF () const
	Returns the variant as a QRectF if the variant has userType() \l QMetaType::QRect or \l QMetaType::QRectF; otherwise returns an invalid QRectF.
QLocale	toLocale () const
	Returns the variant as a QLocale if the variant has userType() \l QMetaType::QLocale; otherwise returns an invalid QLocale.
QUuid	toUuid () const
QUrl	toUrl () const
	Returns the variant as a QUrl if the variant has userType() \l QMetaType::QUrl; otherwise returns an invalid QUrl.
QJsonValue	toJsonValue () const
QJsonObject	toJsonObject () const
QJsonArray	toJsonArray () const
QJsonDocument	toJsonDocument () const
void	load (QDataStream &ds)
	Internal function for loading a variant from stream s.
void	save (QDataStream &ds) const
	Internal function for saving a variant to the stream s.
void *	data ()
	Returns a pointer to the contained object as a generic void* that can be written to.
const void *	constData () const
const void *	data () const
	Returns a pointer to the contained object as a generic void* that cannot be written to.
template<typename T, typename... Args, if_constructible< T, Args... > = true>
T &	emplace (Args &&... args)
template<typename T, typename U, typename... Args, if_constructible< T, std::initializer_list< U > &, Args... > = true>
T &	emplace (std::initializer_list< U > list, Args &&... args)
template<typename T, typename = std::enable_if_t<!std::is_same_v<std::decay_t<T>, QVariant>>>
void	setValue (T &&avalue)
void	setValue (const QVariant &avalue)
	Copies value over this QVariant.
void	setValue (QVariant &&avalue)
	Moves value over this QVariant.
template<typename T>
T	value () const &
template<typename T>
T	view ()
	Returns a mutable view of template type {T} on the stored value.
template<typename T>
T	value () &&
template<typename T>
bool	canConvert () const
	Returns `true` if the variant can be converted to the template type {T}, otherwise false.
template<typename T>
bool	canView () const
	Returns `true` if a mutable view of the template type {T} can be created on this variant, otherwise `false`.
DataPtr &	data_ptr ()
const DataPtr &	data_ptr () const

Static Public Member Functions
template<typename T, if_rvalue< T > = true>
static auto	fromValue (T &&value) noexcept(std::is_nothrow_copy_constructible_v< T > &&Private::CanUseInternalSpace< T >) -> std::enable_if_t< std::conjunction_v< std::is_copy_constructible< T >, std::is_destructible< T > >, QVariant >
template<typename T>
static auto	fromValue (const T &value) noexcept(std::is_nothrow_copy_constructible_v< T > &&Private::CanUseInternalSpace< T >) -> std::enable_if_t< std::is_copy_constructible_v< T > &&std::is_destructible_v< T >, QVariant >
	Returns a QVariant containing a copy of value.
template<typename... Types>
static QVariant	fromStdVariant (const std::variant< Types... > &value)
template<typename... Types>
static QVariant	fromStdVariant (std::variant< Types... > &&value)
static QVariant	fromMetaType (QMetaType type, const void *copy=nullptr)
static QPartialOrdering	compare (const QVariant &lhs, const QVariant &rhs)
	Compares the objects at lhs and rhs for ordering.

Protected Member Functions
void	create (int type, const void *copy)
void	create (QMetaType type, const void *copy)
bool	equals (const QVariant &other) const
bool	convert (int type, void *ptr) const
bool	view (int type, void *ptr)

Protected Attributes
Private	d

Friends
bool	comparesEqual (const QVariant &a, const QVariant &b)
template<typename T>
auto	operator<< (const QDebug &debug, const T &variant) -> std::enable_if_t< std::is_same_v< T, QVariant >, QDebug >
template<typename T>
T *	get_if (QVariant *v) noexcept
	If v contains an object of type `T`, returns a pointer to the contained object, otherwise returns \nullptr.
template<typename T>
const T *	get_if (const QVariant *v) noexcept
template<typename T>
T	qvariant_cast (const QVariant &v)
	Returns the given value converted to the template type {T}.
template<typename T>
T	qvariant_cast (QVariant &&v)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Related Symbols
(Note that these are not member symbols.)
QDataStream &	operator>> (QDataStream &s, QVariant &p)
QDataStream &	operator<< (QDataStream &s, const QVariant &p)
	Writes a variant p to the stream s.
QDataStream &	operator>> (QDataStream &s, QVariant::Type &p)
QDataStream &	operator<< (QDataStream &s, const QVariant::Type p)
template< typename T > T	qVariantValue (const QVariant &value)
bool	qVariantCanConvert (const QVariant &value)
	QVariantList
	Synonym for QList<QVariant>.
	QVariantMap
	Synonym for QMap<QString, QVariant>.
	QVariantHash

Detailed Description

\inmodule QtCore

The QVariant class acts like a union for the most common Qt data types.

\compares equality

A QVariant object holds a single value of a single typeId() at a time. (Some types are multi-valued, for example a string list.) You can find out what type, T, the variant holds, convert it to a different type using convert(), get its value using one of the toT() functions (e.g., toSize()), and check whether the type can be converted to a particular type using canConvert().

The methods named toT() (e.g., toInt(), toString()) are const. If you ask for the stored type, they return a copy of the stored object. If you ask for a type that can be generated from the stored type, toT() copies and converts and leaves the object itself unchanged. If you ask for a type that cannot be generated from the stored type, the result depends on the type; see the function documentation for details.

Here is some example code to demonstrate the use of QVariant:

        QDataStream out("...");
        QVariant v(123);                // The variant now contains an int
        int x = v.toInt();              // x = 123
        out << v;                       // Writes a type tag and an int to out
        v = QVariant(tr("hello"));      // The variant now contains a QString
        int y = v.toInt();              // y = 0 since v cannot be converted to an int
        QString s = v.toString();       // s = tr("hello")  (see QObject::tr())
        out << v;                       // Writes a type tag and a QString to out
        //...
        QDataStream in("...");            // (opening the previously written stream)
        in >> v;                        // Reads an Int variant
        int z = v.toInt();              // z = 123
        qDebug("Type is %s",            // prints "Type is int"
                v.typeName());
        v = v.toInt() + 100;            // The variant now holds the value 223
        v = QVariant(QStringList());    // The variant now holds a QStringList

You can even store QList<QVariant> and QMap<QString, QVariant> values in a variant, so you can easily construct arbitrarily complex data structures of arbitrary types. This is very powerful and versatile, but may prove less memory and speed efficient than storing specific types in standard data structures.

QVariant also supports the notion of null values. A variant is null if the variant contains no initialized value, or contains a null pointer.

QVariant x; // x.isNull() == true

QVariant y = QVariant::fromValue(nullptr); // y.isNull() == true

QVariant can be extended to support other types than those mentioned in the \l QMetaType::Type enum. See \l{Creating Custom Qt Types}{Creating Custom Qt Types} for details.

Definition at line 78 of file qvariant.h.

Member Typedef Documentation

◆ DataPtr

typedef Private QVariant::DataPtr

Definition at line 840 of file qvariant.h.

Constructor & Destructor Documentation

◆ QVariant() [1/46]

QVariant::QVariant ( )

inlinenoexcept

Constructs an invalid variant.

Definition at line 231 of file qvariant.h.

◆ ~QVariant()

QVariant::~QVariant ( )

Destroys the QVariant and the contained object.

Definition at line 520 of file qvariant.cpp.

◆ QVariant() [2/46]

QVariant::QVariant	(	QMetaType	type,
		const void *	copy = nullptr )

explicit

Constructs a variant of type type, and initializes it with a copy of {*copy} if copy is not \nullptr (in which case, copy must point to an object of type type).

Note that you have to pass the address of the object you want stored.

Usually, you never have to use this constructor, use QVariant::fromValue() instead to construct variants from the pointer types represented by QMetaType::VoidStar, and QMetaType::QObjectStar.

If type does not support copy construction and copy is not \nullptr, the variant will be invalid. Similarly, if copy is \nullptr and type does not support default construction, the variant will be invalid.

See also: QVariant::fromMetaType, QVariant::fromValue(), QMetaType::Type

Definition at line 921 of file qvariant.cpp.

◆ QVariant() [3/46]

QVariant::QVariant ( const QVariant & other )

Constructs a copy of the variant, p, passed as the argument to this constructor.

Definition at line 533 of file qvariant.cpp.

◆ QVariant() [4/46]

template<typename T, typename... Args, if_constructible< T, Args... > = true>

QVariant::QVariant	(	std::in_place_type_t< T >	,
		Args &&...	args )

inlineexplicitnoexcept

Definition at line 363 of file qvariant.h.

◆ QVariant() [5/46]

template<typename T, typename U, typename... Args, if_constructible< T, std::initializer_list< U > &, Args... > = true>

QVariant::QVariant	(	std::in_place_type_t< T >	,
		std::initializer_list< U >	il,
		Args &&...	args )

inlineexplicitnoexcept

Definition at line 373 of file qvariant.h.

◆ QVariant() [6/46]

QVariant::QVariant ( int i )

noexcept

Constructs a new variant with an integer value, val.

Definition at line 926 of file qvariant.cpp.

◆ QVariant() [7/46]

QVariant::QVariant ( uint ui )

noexcept

Constructs a new variant with an unsigned integer value, val.

Definition at line 927 of file qvariant.cpp.

◆ QVariant() [8/46]

QVariant::QVariant ( qlonglong ll )

noexcept

Constructs a new variant with a long long integer value, val.

Definition at line 928 of file qvariant.cpp.

◆ QVariant() [9/46]

QVariant::QVariant ( qulonglong ull )

noexcept

Constructs a new variant with an unsigned long long integer value, val.

Definition at line 929 of file qvariant.cpp.

◆ QVariant() [10/46]

QVariant::QVariant ( bool b )

noexcept

Constructs a new variant with a boolean value, val.

Definition at line 930 of file qvariant.cpp.

◆ QVariant() [11/46]

QVariant::QVariant ( double d )

noexcept

Constructs a new variant with a floating point value, val.

Definition at line 931 of file qvariant.cpp.

◆ QVariant() [12/46]

QVariant::QVariant ( float val )

noexcept

Constructs a new variant with a floating point value, val.

Since: 4.6

Definition at line 932 of file qvariant.cpp.

◆ QVariant() [13/46]

QVariant::QVariant ( QChar qchar )

noexcept

Constructs a new variant with a char value, c.

Definition at line 937 of file qvariant.cpp.

◆ QVariant() [14/46]

QVariant::QVariant ( QDate date )

noexcept

Constructs a new variant with a date value, val.

Definition at line 940 of file qvariant.cpp.

◆ QVariant() [15/46]

QVariant::QVariant ( QTime time )

noexcept

Constructs a new variant with a time value, val.

Definition at line 941 of file qvariant.cpp.

◆ QVariant() [16/46]

QVariant::QVariant ( const QBitArray & bitarray )

noexcept

Constructs a new variant with a bitarray value, val.

Definition at line 935 of file qvariant.cpp.

◆ QVariant() [17/46]

QVariant::QVariant ( const QByteArray & bytearray )

noexcept

Constructs a new variant with a bytearray value, val.

Definition at line 934 of file qvariant.cpp.

◆ QVariant() [18/46]

QVariant::QVariant ( const QDateTime & datetime )

noexcept

Constructs a new variant with a date/time value, val.

Definition at line 942 of file qvariant.cpp.

◆ QVariant() [19/46]

QVariant::QVariant ( const QHash< QString, QVariant > & hash )

noexcept

Constructs a new variant with a hash of \l {QVariant}s, val.

Definition at line 946 of file qvariant.cpp.

◆ QVariant() [20/46]

QVariant::QVariant ( const QJsonArray & val )

noexcept

Since: 5.0

Constructs a new variant with a json array value, val.

Definition at line 979 of file qvariant.cpp.

◆ QVariant() [21/46]

QVariant::QVariant ( const QJsonObject & val )

noexcept

Since: 5.0

Constructs a new variant with a json object value, val.

Definition at line 978 of file qvariant.cpp.

◆ QVariant() [22/46]

QVariant::QVariant ( const QList< QVariant > & list )

noexcept

Constructs a new variant with a list value, val.

Definition at line 944 of file qvariant.cpp.

◆ QVariant() [23/46]

QVariant::QVariant ( const QLocale & locale )

noexcept

Constructs a new variant with a locale value, l.

Definition at line 970 of file qvariant.cpp.

◆ QVariant() [24/46]

QVariant::QVariant ( const QMap< QString, QVariant > & map )

noexcept

Constructs a new variant with a map of \l {QVariant}s, val.

Definition at line 945 of file qvariant.cpp.

◆ QVariant() [25/46]

QVariant::QVariant ( const QRegularExpression & re )

noexcept

Since: 5.0

Constructs a new variant with the regular expression value re.

◆ QVariant() [26/46]

QVariant::QVariant ( const QString & string )

noexcept

Constructs a new variant with a string value, val.

Definition at line 936 of file qvariant.cpp.

◆ QVariant() [27/46]

QVariant::QVariant ( const QStringList & stringlist )

noexcept

Constructs a new variant with a string list value, val.

Definition at line 938 of file qvariant.cpp.

◆ QVariant() [28/46]

QVariant::QVariant ( const QUrl & url )

noexcept

Constructs a new variant with a url value of val.

Definition at line 969 of file qvariant.cpp.

◆ QVariant() [29/46]

QVariant::QVariant ( const QJsonValue & val )

noexcept

Since: 5.0

Constructs a new variant with a json value, val.

Definition at line 975 of file qvariant.cpp.

◆ QVariant() [30/46]

QVariant::QVariant ( const QModelIndex & val )

noexcept

Since: 5.0

Constructs a new variant with a QModelIndex value, val.

◆ QVariant() [31/46]

QVariant::QVariant ( QUuid val )

noexcept

Since: 5.0

Constructs a new variant with an uuid value, val.

Definition at line 974 of file qvariant.cpp.

◆ QVariant() [32/46]

QVariant::QVariant ( QSize size )

noexcept

Constructs a new variant with a size value of val.

Definition at line 965 of file qvariant.cpp.

◆ QVariant() [33/46]

QVariant::QVariant ( QSizeF size )

noexcept

Constructs a new variant with a size value of val.

Definition at line 967 of file qvariant.cpp.

◆ QVariant() [34/46]

QVariant::QVariant ( QPoint pt )

noexcept

Constructs a new variant with a point value of val.

Definition at line 953 of file qvariant.cpp.

◆ QVariant() [35/46]

QVariant::QVariant ( QPointF pt )

noexcept

Constructs a new variant with a point value of val.

Definition at line 955 of file qvariant.cpp.

◆ QVariant() [36/46]

QVariant::QVariant ( QLine line )

noexcept

Constructs a new variant with a line value of val.

Definition at line 961 of file qvariant.cpp.

◆ QVariant() [37/46]

QVariant::QVariant ( QLineF line )

noexcept

Constructs a new variant with a line value of val.

Definition at line 963 of file qvariant.cpp.

◆ QVariant() [38/46]

QVariant::QVariant ( QRect rect )

noexcept

Constructs a new variant with a rect value of val.

Definition at line 957 of file qvariant.cpp.

◆ QVariant() [39/46]

QVariant::QVariant ( QRectF rect )

noexcept

Constructs a new variant with a rect value of val.

Definition at line 959 of file qvariant.cpp.

◆ QVariant() [40/46]

QVariant::QVariant ( const QEasingCurve & val )

Since: 4.7

Constructs a new variant with an easing curve value, val.

◆ QVariant() [41/46]

QVariant::QVariant ( const QJsonDocument & val )

Since: 5.0

Constructs a new variant with a json document value, val.

Definition at line 980 of file qvariant.cpp.

◆ QVariant() [42/46]

QVariant::QVariant ( const QPersistentModelIndex & val )

Since: 5.5

Constructs a new variant with a QPersistentModelIndex value, val.

◆ QVariant() [43/46]

QT_ASCII_CAST_WARN QVariant::QVariant ( const char * val )

inline

Constructs a new variant with a string value of val.

The variant creates a deep copy of val into a QString assuming UTF-8 encoding on the input val.

Note that val is converted to a QString for storing in the variant and QVariant::userType() will return QMetaType::QString for the variant.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications.

Definition at line 431 of file qvariant.h.

◆ QVariant() [44/46]

QVariant::QVariant ( QLatin1StringView string )

Constructs a new variant with a QString value from the Latin-1 string viewed by val.

Definition at line 948 of file qvariant.cpp.

◆ QVariant() [45/46]

template<typename T, std::enable_if_t< std::disjunction_v< std::is_pointer< T >, std::is_member_pointer< T > >, bool > = false>

QVariant::QVariant ( T )

delete

◆ QVariant() [46/46]

QVariant::QVariant ( QVariant && other )

inlinenoexcept

Move-constructs a QVariant instance, making it point at the same object that other was pointing to.

Since: 5.2

Definition at line 459 of file qvariant.h.

Member Function Documentation

◆ canConvert() [1/2]

template<typename T>

bool QVariant::canConvert ( ) const

inline

Returns true if the variant can be converted to the template type {T}, otherwise false.

Example:

        QVariant v = 42;
 
        v.canConvert<int>();              // returns true
        v.canConvert<QString>();          // returns true
 
        MyCustomStruct s;
        v.setValue(s);
 
        v.canConvert<int>();              // returns false
        v.canConvert<MyCustomStruct>();   // returns true

A QVariant containing a pointer to a type derived from QObject will also return true for this function if a qobject_cast to the template type {T} would succeed. Note that this only works for QObject subclasses which use the Q_OBJECT macro.

See also: convert()

Definition at line 728 of file qvariant.h.

◆ canConvert() [2/2]

bool QVariant::canConvert ( QMetaType type ) const

inline

Since: 6.0

Returns true if the variant's type can be cast to the requested type, type. Such casting is done automatically when calling the toInt(), toBool(), ... methods.

Note this function operates only on the variant's type, not the contents. It indicates whether there is a conversion path from this variant to type, not that the conversion will succeed when attempted.

See also: QMetaType::canConvert()

Definition at line 482 of file qvariant.h.

◆ canView() [1/2]

template<typename T>

bool QVariant::canView ( ) const

inline

Returns true if a mutable view of the template type {T} can be created on this variant, otherwise false.

See also: value()

Definition at line 732 of file qvariant.h.

◆ canView() [2/2]

bool QVariant::canView ( QMetaType targetType ) const

inline

Definition at line 486 of file qvariant.h.

◆ clear()

void QVariant::clear ( )

Convert this variant to type QMetaType::UnknownType and free up any resources used.

Definition at line 1097 of file qvariant.cpp.

◆ compare()

QPartialOrdering QVariant::compare	(	const QVariant &	lhs,
		const QVariant &	rhs )

static

Compares the objects at lhs and rhs for ordering.

Returns QPartialOrdering::Unordered if comparison is not supported or the values are unordered. Otherwise, returns QPartialOrdering::Less, QPartialOrdering::Equivalent or QPartialOrdering::Greater if lhs is less than, equivalent to or greater than rhs, respectively.

If the variants contain data with a different metatype, the values are considered unordered unless they are both of numeric or pointer types, where regular numeric or pointer comparison rules will be used.

Note: : If a numeric comparison is done and at least one value is NaN, QPartialOrdering::Unordered is returned.

If both variants contain data of the same metatype, the method will use the QMetaType::compare method to determine the ordering of the two variants, which can also indicate that it can't establish an ordering between the two values.

Since: 6.0

See also: QMetaType::compare(), QMetaType::isOrdered()

Definition at line 2389 of file qvariant.cpp.

◆ constData()

const void * QVariant::constData ( ) const

inline

Definition at line 582 of file qvariant.h.

◆ convert() [1/2]

bool QVariant::convert	(	int	type,
		void *	ptr ) const

protected

Created for qvariant_cast() usage

Definition at line 2111 of file qvariant.cpp.

◆ convert() [2/2]

bool QVariant::convert ( QMetaType targetType )

Casts the variant to the requested type, targetType.

If the cast cannot be done, the variant is still changed to the requested type, but is left in a cleared null state similar to that constructed by QVariant(Type).

Returns true if the current type of the variant was successfully cast; otherwise returns false.

A QVariant containing a pointer to a type derived from QObject will also convert and return true for this function if a qobject_cast to the type described by targetType would succeed. Note that this only works for QObject subclasses which use the Q_OBJECT macro.

Note: converting QVariants that are null due to not being initialized or having failed a previous conversion will always fail, changing the type, remaining null, and returning false.

Since: 6.0

See also: canConvert(), clear()

Definition at line 2085 of file qvariant.cpp.

◆ create() [1/2]

void QVariant::create	(	int	type,
		const void *	copy )

protected

Constructs a variant private of type type, and initializes with copy if copy is not \nullptr.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 498 of file qvariant.cpp.

◆ create() [2/2]

void QVariant::create	(	QMetaType	type,
		const void *	copy )

protected

Definition at line 509 of file qvariant.cpp.

◆ data() [1/2]

void * QVariant::data ( )

Returns a pointer to the contained object as a generic void* that can be written to.

This function detaches the QVariant. When called on a \l{isNull}{null-QVariant}, the QVariant will not be null after the call.

See also: get_if(), QMetaType

Definition at line 2422 of file qvariant.cpp.

◆ data() [2/2]

const void * QVariant::data ( ) const

inline

Returns a pointer to the contained object as a generic void* that cannot be written to.

See also: get_if(), QMetaType

Definition at line 584 of file qvariant.h.

◆ data_ptr() [1/2]

DataPtr & QVariant::data_ptr ( )

inline

Definition at line 841 of file qvariant.h.

◆ data_ptr() [2/2]

const DataPtr & QVariant::data_ptr ( ) const

inline

Definition at line 842 of file qvariant.h.

◆ detach()

void QVariant::detach ( )

Definition at line 1064 of file qvariant.cpp.

◆ emplace() [1/2]

template<typename T, typename... Args, if_constructible< T, Args... > = true>

T & QVariant::emplace ( Args &&... args )

inline

Since: 6.6 Replaces the object currently held in {*this} with an object of type {T}, constructed from {args}{...}. If {*this} was non-null, the previously held object is destroyed first. If possible, this method will reuse memory allocated by the QVariant. Returns a reference to the newly-created object.

Definition at line 611 of file qvariant.h.

◆ emplace() [2/2]

template<typename T, typename U, typename... Args, if_constructible< T, std::initializer_list< U > &, Args... > = true>

T & QVariant::emplace	(	std::initializer_list< U >	list,
		Args &&...	args )

inline

Since: 6.6 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. This overload exists to support types with constructors taking an initializer_list. It behaves otherwise equivalent to the non-initializer list overload.

Definition at line 618 of file qvariant.h.

◆ equals()

bool QVariant::equals ( const QVariant & v ) const

protected

Definition at line 2346 of file qvariant.cpp.

◆ fromMetaType()

QVariant QVariant::fromMetaType	(	QMetaType	type,
		const void *	copy = nullptr )

static

Since: 6.7

Creates a variant of type type, and initializes it with a copy of {*copy} if copy is not \nullptr (in which case, copy must point to an object of type type).

Note that you have to pass the address of the object you want stored.

Usually, you never have to use this constructor, use QVariant::fromValue() instead to construct variants from the pointer types represented by QMetaType::VoidStar, and QMetaType::QObjectStar.

If type does not support copy construction and copy is not \nullptr, the variant will be invalid. Similarly, if copy is \nullptr and type does not support default construction, the variant will be invalid.

Returns the QVariant created as described above.

See also: QVariant::fromValue(), QMetaType::Type

Definition at line 2688 of file qvariant.cpp.

◆ fromStdVariant() [1/2]

template<typename... Types>

QVariant QVariant::fromStdVariant ( const std::variant< Types... > & value )

inlinestatic

Since: 5.11

Returns a QVariant with the type and value of the active variant of value. If the active type is std::monostate a default QVariant is returned.

Note: With this method you do not need to register the variant as a Qt metatype, since the std::variant is resolved before being stored. The component types should be registered however.

See also: fromValue()

Definition at line 714 of file qvariant.h.

◆ fromStdVariant() [2/2]

template<typename... Types>

QVariant QVariant::fromStdVariant ( std::variant< Types... > && value )

inlinestatic

Since: 6.6 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 720 of file qvariant.h.

◆ fromValue() [1/2]

template<typename T>

auto QVariant::fromValue ( const T & value ) -> std::enable_if_t<std::is_copy_constructible_v<T> && std::is_destructible_v<T>, QVariant>

inlinestaticnoexcept

Returns a QVariant containing a copy of value.

Behaves exactly like setValue() otherwise.

Example:

MyCustomStruct s;

return QVariant::fromValue(s);

See also: setValue(), value()

Definition at line 697 of file qvariant.h.

◆ fromValue() [2/2]

template<typename T, if_rvalue< T > = true>

auto QVariant::fromValue ( T && value ) -> std::enable_if_t<std::conjunction_v<std::is_copy_constructible<T>, std::is_destructible<T>>, QVariant>

inlinestaticnoexcept

Since: 6.6 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 668 of file qvariant.h.

◆ isDetached()

bool QVariant::isDetached ( ) const

inline

Definition at line 888 of file qvariant.h.

◆ isNull()

bool QVariant::isNull ( ) const

Returns true if this is a null variant, false otherwise.

A variant is considered null if it contains no initialized value or a null pointer.

Note: This behavior has been changed from Qt 5, where isNull() would also return true if the variant contained an object of a builtin type with an isNull() method that returned true for that object.

See also: convert()

Definition at line 2477 of file qvariant.cpp.

◆ isValid()

bool QVariant::isValid ( ) const

inline

Returns true if the storage type of this variant is not QMetaType::UnknownType; otherwise returns false.

Definition at line 845 of file qvariant.h.

◆ load()

void QVariant::load ( QDataStream & s )

Internal function for loading a variant from stream s.

Use the stream operators instead.

Definition at line 1191 of file qvariant.cpp.

◆ metaType()

QMetaType QVariant::metaType ( ) const

Since: 6.0

Returns the QMetaType of the value stored in the variant.

◆ operator=()

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

Move-assigns other to this QVariant instance.

Assigns the value of the variant variant to this variant.

Since: 5.2

Definition at line 1042 of file qvariant.cpp.

◆ save()

void QVariant::save ( QDataStream & s ) const

Internal function for saving a variant to the stream s.

Use the stream operators instead.

Definition at line 1271 of file qvariant.cpp.

◆ setValue() [1/3]

void QVariant::setValue ( const QVariant & value )

inline

Copies value over this QVariant.

It is equivalent to simply assigning value to this QVariant.

Definition at line 637 of file qvariant.h.

◆ setValue() [2/3]

void QVariant::setValue ( QVariant && value )

inline

Moves value over this QVariant.

It is equivalent to simply move assigning value to this QVariant.

Definition at line 642 of file qvariant.h.

◆ setValue() [3/3]

template<typename T, typename = std::enable_if_t<!std::is_same_v<std::decay_t<T>, QVariant>>>

void QVariant::setValue ( T && avalue )

inline

Definition at line 624 of file qvariant.h.

◆ swap()

void QVariant::swap ( QVariant & other )

inlinenoexcept

Since: 4.8 \memberswap{variant}

Definition at line 463 of file qvariant.h.

◆ toBitArray()

QBitArray QVariant::toBitArray ( ) const

Returns the variant as a QBitArray if the variant has userType() \l QMetaType::QBitArray; otherwise returns an empty bit array.

See also: canConvert(), convert()

Definition at line 1822 of file qvariant.cpp.

◆ toBool()

bool QVariant::toBool ( ) const

Returns the variant as a bool if the variant has userType() Bool.

Returns true if the variant has userType() \l QMetaType::Bool, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::UInt, or \l QMetaType::ULongLong and the value is non-zero, or if the variant has type \l QMetaType::QString or \l QMetaType::QByteArray and its lower-case content is not one of the following: empty, "0" or "false"; otherwise returns false.

See also: canConvert(), convert()

Definition at line 1934 of file qvariant.cpp.

◆ toByteArray()

QByteArray QVariant::toByteArray ( ) const

Returns the variant as a QByteArray if the variant has userType() \l QMetaType::QByteArray or \l QMetaType::QString (converted using QString::fromUtf8()); otherwise returns an empty byte array.

See also: canConvert(), convert()

Definition at line 1554 of file qvariant.cpp.

◆ toChar()

QChar QVariant::toChar ( ) const

Returns the variant as a QChar if the variant has userType() \l QMetaType::QChar, \l QMetaType::Int, or \l QMetaType::UInt; otherwise returns an invalid QChar.

See also: canConvert(), convert()

Definition at line 1811 of file qvariant.cpp.

◆ toDate()

QDate QVariant::toDate ( ) const

Returns the variant as a QDate if the variant has userType() \l QMetaType::QDate, \l QMetaType::QDateTime, or \l QMetaType::QString; otherwise returns an invalid date.

If the metaType() is \l QMetaType::QString, an invalid date will be returned if the string cannot be parsed as a Qt::ISODate format date.

See also: canConvert(), convert()

Definition at line 1490 of file qvariant.cpp.

◆ toDateTime()

QDateTime QVariant::toDateTime ( ) const

Returns the variant as a QDateTime if the variant has userType() \l QMetaType::QDateTime, \l QMetaType::QDate, or \l QMetaType::QString; otherwise returns an invalid date/time.

If the metaType() is \l QMetaType::QString, an invalid date/time will be returned if the string cannot be parsed as a Qt::ISODate format date/time.

See also: canConvert(), convert()

Definition at line 1524 of file qvariant.cpp.

◆ toDouble()

double QVariant::toDouble ( bool * ok = nullptr ) const

Returns the variant as a double if the variant has userType() \l QMetaType::Double, \l QMetaType::Float, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.0.

If ok is non-null: {*}{ok} is set to true if the value could be converted to a double; otherwise {*}{ok} is set to false.

See also: canConvert(), convert()

Definition at line 1957 of file qvariant.cpp.

◆ toFloat()

float QVariant::toFloat ( bool * ok = nullptr ) const

Returns the variant as a float if the variant has userType() \l QMetaType::Double, \l QMetaType::Float, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.0.

Since: 4.6

If ok is non-null: {*}{ok} is set to true if the value could be converted to a double; otherwise {*}{ok} is set to false.

See also: canConvert(), convert()

Definition at line 1976 of file qvariant.cpp.

◆ toHash()

QVariantHash QVariant::toHash ( ) const

Returns the variant as a QHash<QString, QVariant> if the variant has metaType() \l QMetaType::QVariantHash; otherwise returns an empty map.

See also: canConvert(), convert()

Definition at line 1473 of file qvariant.cpp.

◆ toInt()

int QVariant::toInt ( bool * ok = nullptr ) const

Returns the variant as an int if the variant has userType() \l QMetaType::Int, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.

If ok is non-null: {*}{ok} is set to true if the value could be converted to an int; otherwise {*}{ok} is set to false.

{Warning:} If the value is convertible to a \l QMetaType::LongLong but is too large to be represented in an int, the resulting arithmetic overflow will not be reflected in ok. A simple workaround is to use QString::toInt().

See also: canConvert(), convert()

Definition at line 1861 of file qvariant.cpp.

◆ toJsonArray()

QJsonArray QVariant::toJsonArray ( ) const

Since: 5.0

Returns the variant as a QJsonArray if the variant has userType() \l QJsonArray; otherwise returns a default constructed QJsonArray.

See also: canConvert(), convert()

Definition at line 1784 of file qvariant.cpp.

◆ toJsonDocument()

QJsonDocument QVariant::toJsonDocument ( ) const

Since: 5.0

Returns the variant as a QJsonDocument if the variant has userType() \l QJsonDocument; otherwise returns a default constructed QJsonDocument.

See also: canConvert(), convert()

Definition at line 1797 of file qvariant.cpp.

◆ toJsonObject()

QJsonObject QVariant::toJsonObject ( ) const

Since: 5.0

Returns the variant as a QJsonObject if the variant has userType() \l QJsonObject; otherwise returns a default constructed QJsonObject.

See also: canConvert(), convert()

Definition at line 1771 of file qvariant.cpp.

◆ toJsonValue()

QJsonValue QVariant::toJsonValue ( ) const

Since: 5.0

Returns the variant as a QJsonValue if the variant has userType() \l QJsonValue; otherwise returns a default constructed QJsonValue.

See also: canConvert(), convert()

Definition at line 1758 of file qvariant.cpp.

◆ toLine()

QLine QVariant::toLine ( ) const

Returns the variant as a QLine if the variant has userType() \l QMetaType::QLine; otherwise returns an invalid QLine.

See also: canConvert(), convert()

Definition at line 1647 of file qvariant.cpp.

◆ toLineF()

QLineF QVariant::toLineF ( ) const

Returns the variant as a QLineF if the variant has userType() \l QMetaType::QLineF; otherwise returns an invalid QLineF.

See also: canConvert(), convert()

Definition at line 1634 of file qvariant.cpp.

◆ toList()

QVariantList QVariant::toList ( ) const

Returns the variant as a QVariantList if the variant has userType() \l QMetaType::QVariantList.

If it doesn't, QVariant will attempt to convert the type to a list and then return it. This will succeed for any type that has registered a converter to QVariantList or which was declared as a sequential container using \l{Q_DECLARE_SEQUENTIAL_CONTAINER_METATYPE}. If none of those conditions are true, this function will return an empty list.

See also: canConvert(), convert()

Definition at line 2011 of file qvariant.cpp.

◆ toLocale()

QLocale QVariant::toLocale ( ) const

Returns the variant as a QLocale if the variant has userType() \l QMetaType::QLocale; otherwise returns an invalid QLocale.

See also: canConvert(), convert()

Definition at line 1687 of file qvariant.cpp.

◆ toLongLong()

qlonglong QVariant::toLongLong ( bool * ok = nullptr ) const

Returns the variant as a long long int if the variant has userType() \l QMetaType::LongLong, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.

If ok is non-null: {*}{ok} is set to true if the value could be converted to an int; otherwise {*}{ok} is set to false.

See also: canConvert(), convert()

Definition at line 1900 of file qvariant.cpp.

◆ toMap()

QVariantMap QVariant::toMap ( ) const

Returns the variant as a QVariantMap if the variant has metaType() \l QMetaType::QVariantMap.

If it doesn't, QVariant will attempt to convert the type to a map and then return it. This will succeed for any type that has registered a converter to QVariantMap or which was declared as a associative container using \l{Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE}. If none of those conditions are true, this function will return an empty map.

See also: canConvert(), convert()

Definition at line 1462 of file qvariant.cpp.

◆ toPoint()

QPoint QVariant::toPoint ( ) const

Returns the variant as a QPoint if the variant has userType() \l QMetaType::QPoint or \l QMetaType::QPointF; otherwise returns a null QPoint.

See also: canConvert(), convert()

Definition at line 1568 of file qvariant.cpp.

◆ toPointF()

QPointF QVariant::toPointF ( ) const

Returns the variant as a QPointF if the variant has userType() \l QMetaType::QPoint or \l QMetaType::QPointF; otherwise returns a null QPointF.

See also: canConvert(), convert()

Definition at line 1661 of file qvariant.cpp.

◆ toReal()

qreal QVariant::toReal ( bool * ok = nullptr ) const

Returns the variant as a qreal if the variant has userType() \l QMetaType::Double, \l QMetaType::Float, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, \l QMetaType::UInt, or \l QMetaType::ULongLong; otherwise returns 0.0.

Since: 4.6

If ok is non-null: {*}{ok} is set to true if the value could be converted to a double; otherwise {*}{ok} is set to false.

See also: canConvert(), convert()

Definition at line 1995 of file qvariant.cpp.

◆ toRect()

QRect QVariant::toRect ( ) const

Returns the variant as a QRect if the variant has userType() \l QMetaType::QRect; otherwise returns an invalid QRect.

See also: canConvert(), convert()

Definition at line 1581 of file qvariant.cpp.

◆ toRectF()

QRectF QVariant::toRectF ( ) const

Returns the variant as a QRectF if the variant has userType() \l QMetaType::QRect or \l QMetaType::QRectF; otherwise returns an invalid QRectF.

See also: canConvert(), convert()

Definition at line 1621 of file qvariant.cpp.

◆ toSize()

QSize QVariant::toSize ( ) const

Returns the variant as a QSize if the variant has userType() \l QMetaType::QSize; otherwise returns an invalid QSize.

See also: canConvert(), convert()

Definition at line 1594 of file qvariant.cpp.

◆ toSizeF()

QSizeF QVariant::toSizeF ( ) const

Returns the variant as a QSizeF if the variant has userType() \l QMetaType::QSizeF; otherwise returns an invalid QSizeF.

See also: canConvert(), convert()

Definition at line 1607 of file qvariant.cpp.

◆ toString()

QString QVariant::toString ( ) const

Returns the variant as a QString if the variant has a userType() including, but not limited to:

\l QMetaType::QString, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::QDate, \l QMetaType::QDateTime, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QStringList, \l QMetaType::QTime, \l QMetaType::UInt, or \l QMetaType::ULongLong.

Calling QVariant::toString() on an unsupported variant returns an empty string.

See also: canConvert(), convert()

Definition at line 1446 of file qvariant.cpp.

◆ toStringList()

QStringList QVariant::toStringList ( ) const

Returns the variant as a QStringList if the variant has userType() \l QMetaType::QStringList, \l QMetaType::QString, or \l QMetaType::QVariantList of a type that can be converted to QString; otherwise returns an empty list.

See also: canConvert(), convert()

Definition at line 1426 of file qvariant.cpp.

◆ toTime()

QTime QVariant::toTime ( ) const

Returns the variant as a QTime if the variant has userType() \l QMetaType::QTime, \l QMetaType::QDateTime, or \l QMetaType::QString; otherwise returns an invalid time.

If the metaType() is \l QMetaType::QString, an invalid time will be returned if the string cannot be parsed as a Qt::ISODate format time.

See also: canConvert(), convert()

Definition at line 1507 of file qvariant.cpp.

◆ toUInt()

uint QVariant::toUInt ( bool * ok = nullptr ) const

Returns the variant as an unsigned int if the variant has userType() \l QMetaType::UInt, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, or \l QMetaType::ULongLong; otherwise returns 0.

If ok is non-null: {*}{ok} is set to true if the value could be converted to an unsigned int; otherwise {*}{ok} is set to false.

{Warning:} If the value is convertible to a \l QMetaType::ULongLong but is too large to be represented in an unsigned int, the resulting arithmetic overflow will not be reflected in ok. A simple workaround is to use QString::toUInt().

See also: canConvert(), convert()

Definition at line 1883 of file qvariant.cpp.

◆ toULongLong()

qulonglong QVariant::toULongLong ( bool * ok = nullptr ) const

Returns the variant as an unsigned long long int if the variant has metaType() \l QMetaType::ULongLong, \l QMetaType::Bool, \l QMetaType::QByteArray, \l QMetaType::QChar, \l QMetaType::Double, \l QMetaType::Int, \l QMetaType::LongLong, \l QMetaType::QString, or \l QMetaType::UInt; otherwise returns 0.

If ok is non-null: {*}{ok} is set to true if the value could be converted to an int; otherwise {*}{ok} is set to false.

See also: canConvert(), convert()

Definition at line 1917 of file qvariant.cpp.

◆ toUrl()

QUrl QVariant::toUrl ( ) const

Returns the variant as a QUrl if the variant has userType() \l QMetaType::QUrl; otherwise returns an invalid QUrl.

See also: canConvert(), convert()

Definition at line 1674 of file qvariant.cpp.

◆ toUuid()

QUuid QVariant::toUuid ( ) const

Since: 5.0

Returns the variant as a QUuid if the variant has metaType() \l QMetaType::QUuid, \l QMetaType::QByteArray or \l QMetaType::QString; otherwise returns a default-constructed QUuid.

See also: canConvert(), convert()

Definition at line 1745 of file qvariant.cpp.

◆ typeId()

int QVariant::typeId ( ) const

inline

Returns the storage type of the value stored in the variant.

This is the same as metaType().id().

See also: metaType()

Definition at line 466 of file qvariant.h.

◆ typeName()

const char * QVariant::typeName ( ) const

Returns the name of the type stored in the variant.

The returned strings describe the C++ datatype used to store the data: for example, "QFont", "QString", or "QVariantList". An Invalid variant returns 0.

◆ userType()

int QVariant::userType ( ) const

inline

Definition at line 465 of file qvariant.h.

◆ value() [1/2]

template<typename T>

T QVariant::value ( ) &&

inline

Definition at line 660 of file qvariant.h.

◆ value() [2/2]

template<typename T>

T QVariant::value ( ) const &

inline

Definition at line 648 of file qvariant.h.

◆ view() [1/2]

template<typename T>

T QVariant::view ( )

inline

Returns a mutable view of template type {T} on the stored value.

Call canView() to find out whether such a view is supported. If no such view can be created, returns the stored value converted to the template type {T}. Call canConvert() to find out whether a type can be converted. If the value can neither be viewed nor converted, a \l{default-constructed value} will be returned.

See also: canView(), Q_DECLARE_SEQUENTIAL_CONTAINER_METATYPE()

Definition at line 652 of file qvariant.h.

◆ view() [2/2]

bool QVariant::view	(	int	type,
		void *	ptr )

protected

Definition at line 2119 of file qvariant.cpp.

◆ comparesEqual

bool comparesEqual	(	const QVariant &	a,
		const QVariant &	b )

friend

Definition at line 749 of file qvariant.h.

◆ get_if [1/2]

template<typename T>

const T * get_if ( const QVariant * v )

friend

Since: 6.6

Definition at line 770 of file qvariant.h.

◆ get_if [2/2]

template<typename T>

T * get_if ( QVariant * v )

friend

If v contains an object of type T, returns a pointer to the contained object, otherwise returns \nullptr.

The overload taking a mutable v detaches v: When called on a \l{isNull()}{null} v with matching type T, v will not be null after the call.

These functions are provided for compatibility with {std::variant}.

See also: data()

Definition at line 762 of file qvariant.h.

◆ operator<< [1/3]

template<typename T>

auto operator<<	(	const QDebug &	debug,
		const T &	variant ) -> std::enable_if_t<std::is_same_v<T, QVariant>, QDebug>

friend

Definition at line 755 of file qvariant.h.

◆ operator<<() [2/3]

QDataStream & operator<<	(	QDataStream &	s,
		const QVariant &	p )

Writes a variant p to the stream s.

See also: {Serializing Qt Data Types}{Format of the QDataStream operators}

Definition at line 1388 of file qvariant.cpp.

◆ operator<<() [3/3]

QDataStream & operator<<	(	QDataStream &	s,
		const QVariant::Type	p )

Deprecated: [6.0] Stream QMetaType::Type instead.

Writes a variant type p to the stream s.

Deprecated: [6.0] Stream QMetaType::Type instead.

Writes a variant type p to the stream s.

◆ operator>>() [1/2]

QDataStream & operator>>	(	QDataStream &	s,
		QVariant &	p )

Since: 4.4

Reads a variant p from the stream s.

Note: If the stream contains types that aren't the built-in ones (see \l QMetaType::Type), those types must be registered using qRegisterMetaType() or QMetaType::registerType() before the variant can be properly loaded. If an unregistered type is found, QVariant will set the corrupt flag in the stream, stop processing and print a warning. For example, for QList<int> it would print the following:

\quotation QVariant::load: unknown user type with name QList<int> \endquotation

See also: {Serializing Qt Data Types}{Format of the QDataStream operators}

Definition at line 1376 of file qvariant.cpp.

◆ operator>>() [2/2]

QDataStream & operator>>	(	QDataStream &	s,
		QVariant::Type &	p )

Deprecated: [6.0] Stream QMetaType::Type instead.

Reads a variant type p in enum representation from the stream s.

Deprecated: [6.0] Stream QMetaType::Type instead.

Reads a variant type p in enum representation from the stream s.

◆ qvariant_cast [1/2]

template<typename T>

T qvariant_cast ( const QVariant & value )

friend

Returns the given value converted to the template type {T}.

This function is equivalent to QVariant::value().

See also: QVariant::value()

Definition at line 905 of file qvariant.h.

◆ qvariant_cast [2/2]

template<typename T>

T qvariant_cast ( QVariant && value )

friend

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since: 6.7

Returns the given value converted to the template type {T}.

Definition at line 920 of file qvariant.h.

◆ qVariantCanConvert()

bool qVariantCanConvert ( const QVariant & value )

Deprecated

Returns true if the given value can be converted to the template type specified; otherwise returns false.

This function is equivalent to QVariant::canConvert(value).

Note: This function was provided as a workaround for MSVC 6 which did not support member template functions. It is advised to use the other form in new code.

See also: QVariant::canConvert()

Deprecated

Returns true if the given value can be converted to the template type specified; otherwise returns false.

This function is equivalent to QVariant::canConvert(value).

Note: This function was provided as a workaround for MSVC 6 which did not support member template functions. It is advised to use the other form in new code.

See also: QVariant::canConvert()

◆ QVariantHash()

QVariantHash

Since: 4.5

Synonym for QHash<QString, QVariant>.

Definition at line 53 of file qcontainerfwd.h.

◆ QVariantList()

QVariantList

Synonym for QList<QVariant>.

Definition at line 16 of file qjsonarray.h.

◆ QVariantMap()

QVariantMap

Synonym for QMap<QString, QVariant>.

Definition at line 52 of file qcontainerfwd.h.

◆ qVariantValue()

template< typename T > T qVariantValue ( const QVariant & value )

Deprecated

Returns the given value converted to the template type {T}.

This function is equivalent to \l{QVariant::value()}{QVariant::value}<T>(value).

Note: This function was provided as a workaround for MSVC 6 which did not support member template functions. It is advised to use the other form in new code.

See also: QVariant::value(), qvariant_cast()

Deprecated

Returns the given value converted to the template type {T}.

This function is equivalent to \l{QVariant::value()}{QVariant::value}<T>(value).

Note: This function was provided as a workaround for MSVC 6 which did not support member template functions. It is advised to use the other form in new code.

See also: QVariant::value(), qvariant_cast()

Member Data Documentation

◆ d

Private QVariant::d

protected

Definition at line 803 of file qvariant.h.

The documentation for this class was generated from the following files:

qtbase/src/corelib/kernel/qvariant.h (aa113acde28292611a4774f6e755dda12c7964d6)
qtbase/src/corelib/kernel/qvariant.cpp (aa113acde28292611a4774f6e755dda12c7964d6)

Classes

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Related Symbols

Detailed Description

Member Typedef Documentation

◆ DataPtr

Constructor & Destructor Documentation

◆ QVariant() [1/46]

◆ ~QVariant()

◆ QVariant() [2/46]

◆ QVariant() [3/46]

◆ QVariant() [4/46]

◆ QVariant() [5/46]

◆ QVariant() [6/46]

◆ QVariant() [7/46]

◆ QVariant() [8/46]

◆ QVariant() [9/46]

◆ QVariant() [10/46]

◆ QVariant() [11/46]

◆ QVariant() [12/46]

◆ QVariant() [13/46]

◆ QVariant() [14/46]

◆ QVariant() [15/46]

◆ QVariant() [16/46]

◆ QVariant() [17/46]

◆ QVariant() [18/46]

◆ QVariant() [19/46]

◆ QVariant() [20/46]

◆ QVariant() [21/46]

◆ QVariant() [22/46]

◆ QVariant() [23/46]

◆ QVariant() [24/46]

◆ QVariant() [25/46]

◆ QVariant() [26/46]

◆ QVariant() [27/46]

◆ QVariant() [28/46]

◆ QVariant() [29/46]

◆ QVariant() [30/46]

◆ QVariant() [31/46]

◆ QVariant() [32/46]

◆ QVariant() [33/46]

◆ QVariant() [34/46]

◆ QVariant() [35/46]

◆ QVariant() [36/46]

◆ QVariant() [37/46]

◆ QVariant() [38/46]

◆ QVariant() [39/46]

◆ QVariant() [40/46]

◆ QVariant() [41/46]

◆ QVariant() [42/46]

◆ QVariant() [43/46]

◆ QVariant() [44/46]

◆ QVariant() [45/46]

◆ QVariant() [46/46]

Member Function Documentation

◆ canConvert() [1/2]

◆ canConvert() [2/2]

◆ canView() [1/2]

◆ canView() [2/2]

◆ clear()

◆ compare()

◆ constData()

◆ convert() [1/2]

◆ convert() [2/2]

◆ create() [1/2]

◆ create() [2/2]

◆ data() [1/2]

◆ data() [2/2]

◆ data_ptr() [1/2]

◆ data_ptr() [2/2]

◆ detach()

◆ emplace() [1/2]

◆ emplace() [2/2]

◆ equals()

◆ fromMetaType()