The QUuid class stores a Universally Unique Identifier (UUID). More...

Public Types
enum	Variant

enum	Version

Public Methods
constexpr	QUuid ()

constexpr	QUuid (const GUID &guid)

	QUuid (const QByteArray &text)

	QUuid (const QString &text)

constexpr	QUuid (uint l, ushort w1, ushort w2, uchar b1, uchar b2, uchar b3, uchar b4, uchar b5, uchar b6, uchar b7, uchar b8)

bool	isNull () const

	operator GUID () const

constexpr bool	operator!= (const GUID &guid) const

constexpr bool	operator!= (const QUuid &other) const

bool	operator< (const QUuid &other) const

constexpr QUuid &	operator= (const GUID &guid)

constexpr bool	operator== (const GUID &guid) const

constexpr bool	operator== (const QUuid &other) const

bool	operator> (const QUuid &other) const

QByteArray	toByteArray () const

QByteArray	toRfc4122 () const

QString	toString () const

QUuid::Variant	variant () const

QUuid::Version	version () const

Static Public Methods
static QUuid	createUuid ()

static QUuid	createUuidV3 (const QUuid &ns, const QByteArray &baseData)

static QUuid	createUuidV3 (const QUuid &ns, const QString &baseData)

static QUuid	createUuidV5 (const QUuid &ns, const QByteArray &baseData)

static QUuid	createUuidV5 (const QUuid &ns, const QString &baseData)

static QUuid	fromRfc4122 (const QByteArray &bytes)

Related Functions
These are not member functions
QDataStream &	operator<< (QDataStream &stream, const QUuid &id)

QDataStream &	operator>> (QDataStream &stream, QUuid &id)

Detailed Description

The QUuid class stores a Universally Unique IDentifier (UUID). Using a UUID is a standard way to identify entities in a distributed computing environment. It is a 16-byte (128-bit) number generated by an algorithm which is meant to guarantee the UUID will be unique. The acronym GUID or Globally Unique IDentifier refers to a UUID which was generated by one specific algorithm. Multiple algorithms can be used to generate a UUID. Each algorithm is called a variant.

Each UUID contains a bit field which specifies the variant for that UUID. The method variant() can be used to identify the algorithm used to created the UUID. The variant is stored in the three most significant bits of byte 8.

If you create instances of QUuid using the constructor which accepts all the numeric values as parameters, use the following table to set the three most significant bits of parameter b1. In the table, 'x' means "do not care".

msb0	msb1	msb2	Variant
0	x	x	NCS (Network Computing System)
1	0	x	DCE (Distributed Computing Environment)
1	1	0	Microsoft (GUID)
1	1	1	Reserved for future expansion

If variant() returns QUuid::DCE, the UUID also contains a version field in the four most significant bits of QUuid::data3, and you can call version() to discover which version your QUuid contains. If you create instances of QUuid using the constructor that accepts all the numeric values as parameters, use the following table to set the four most significant bits of parameter w2, which becomes QUuid::data3 and contains the version field in its four most significant bits.

msb1	msb2	msb3	Version
0	0	1	Time
0	1	0	Embedded POSIX
0	1	1	Name
1	0	0	Random

The field layouts for the DCE versions listed in the table above are specified in the Network Working Group UUID Specification.

Most platforms provide a tool for generating new UUIDs, e.g. uuidgen and guidgen. You can also use createUuid(). UUIDs generated by createUuid() are of the random type. Their QUuid::Version bits are set to QUuid::Random, and their QUuid::Variant bits are set to QUuid::DCE. The rest of the UUID is composed of random numbers. Theoretically, this means there is a small chance that a UUID generated by createUuid() will not be unique. But it is a very small chance.

UUIDs can be constructed from numeric values or from strings, or using the static createUuid() method. They can be converted to a string with toString(). UUIDs have a variant() and a version(), and null UUIDs return true from isNull().

See also: toString(), QUuid()

Member Enumeration Documentation

enum QUuid::Variant

This enum defines the values used in the variant field of the UUID. The value in the variant field determines the layout of the 128-bit value.

Constant	Value	Description
`QUuid::VarUnknown`	`-1`	Variant is unknown
`QUuid::NCS`	`0`	Reserved for NCS (Network Computing System) backward compatibility
`QUuid::DCE`	`2`	Distributed Computing Environment, the scheme used by QUuid
`QUuid::Microsoft`	`6`	Reserved for Microsoft backward compatibility (GUID)
`QUuid::Reserved`	`7`	Reserved for future definition

enum QUuid::Version

This enum defines the values used in the version field of the UUID. The version field is meaningful only if the value in the variant field is QUuid::DCE.

Constant	Value	Description
`QUuid::VerUnknown`	`-1`	Version is unknown
`QUuid::Time`	`1`	Time based by using timestamp, clock sequence, and MAC network card address (if available) for the node sections
`QUuid::EmbeddedPOSIX`	`2`	DCE Security version, with embedded POSIX UUIDs
`QUuid::Name`	`3`	Name based by using values from a name for all sections
`QUuid::Random`	`4`	Random based by using random numbers for all sections

Constructor & Destructor Documentation

constexpr QUuid::QUuid ( )

inlineconstexpr

Creates the null UUID. The method toString() will output the null UUID as "{00000000-0000-0000-0000-000000000000}".

constexpr QUuid::QUuid	(	uint	l,
		ushort	w1,
		ushort	w2,
		uchar	b1,
		uchar	b2,
		uchar	b3,
		uchar	b4,
		uchar	b5,
		uchar	b6,
		uchar	b7,
		uchar	b8
	)

inlineconstexpr

Creates a UUID with the value specified by the parameters, l, w1, w2, b1, b2, b3, b4, b5, b6, b7, b8.

// {67C8770B-44F1-410A-AB9A-F9B5446F13EE}

QUuid IID_MyInterface(0x67c8770b, 0x44f1, 0x410a, 0xab, 0x9a, 0xf9, 0xb5, 0x44, 0x6f, 0x13, 0xee)

QUuid::QUuid ( const QString & text )

Creates a QUuid object from the string text. This must be formatted as five hex fields separated by a dash. The value for each x is a hex digit. The curly braces are optional. If the conversion fails, a null UUID is created.

"{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}"

Refer to the methods toString() for documentation about how the five hex fields map to the public data members in QUuid.

See also: toString(), QUuid()

QUuid::QUuid ( const QByteArray & text )

Creates a QUuid object from the QByteArray text. This must be formatted as five hex fields separated by a dash. The value for each x is a hex digit. The curly braces are optional. If the conversion fails, a null UUID is created.

Refer to the methods toByteArray() for documentation about how the five hex fields map to the public data members in QUuid.

See also: toByteArray(), QUuid()

constexpr QUuid::QUuid ( const GUID & guid )

inlineconstexpr

Casts a Windows guid to a QUuid. This method is only available on Windows.

Method Documentation

QUuid QUuid::createUuid ( )

static

On any platform other than Windows, this function returns a new UUID with variant QUuid::DCE and version QUuid::Random. If the /dev/urandom device exists, then the numbers used to construct the UUID will be of cryptographic quality, which will make the UUID unique. Otherwise, the numbers of the UUID will be obtained from the local pseudo-random number generator (qrand(), which is seeded by qsrand()) which is usually not of cryptographic quality, which means that the UUID can not be guaranteed to be unique.

On a Windows platform a GUID is generated which is expected to be unique.

See also: variant(), version()

QUuid QUuid::createUuidV3	(	const QUuid &	ns,
		const QByteArray &	baseData
	)

static

Returns a new UUID with variant QUuid::DCE and version QUuid::Md5.The given ns is the namespace and baseData is the basic data as described by RFC 4122.

See also: variant(), version(), createUuidV5()

QUuid QUuid::createUuidV3	(	const QUuid &	ns,
		const QString &	baseData
	)

inlinestatic

Returns a new UUID with variant QUuid::DCE and version QUuid::Md5. The given ns is the namespace and baseData is the basic data as described by RFC 4122.

See also: variant(), version(), createUuidV5()

QUuid QUuid::createUuidV5	(	const QUuid &	ns,
		const QByteArray &	baseData
	)

static

Returns a new UUID with variant QUuid::DCE and version QUuid::Sha1. The given ns is the namespace and baseData is the basic data as described by RFC 4122.

See also: variant(), version(), createUuidV3()

QUuid QUuid::createUuidV5	(	const QUuid &	ns,
		const QString &	baseData
	)

inlinestatic

Returns a new UUID with variant QUuid::DCE and version QUuid::Sha1. The given ns is the namespace and baseData is the basic data as described by RFC 4122.

See also: variant(), version(), createUuidV3()

QUuid QUuid::fromRfc4122 ( const QByteArray & bytes )

static

Creates a QUuid object from the binary representation of the UUID given by bytes, as specified by RFC 4122 section 4.1.2. The byte array accepted is not a human readable format. If the conversion fails, a null UUID is created.

Refer to toRfc4122() for a further explanation of the order of bytes required.

See also: toRfc4122(), QUuid()

bool QUuid::isNull ( ) const

Returns true if this is the null UUID {00000000-0000-0000-0000-000000000000}, otherwise returns false.

QUuid::operator GUID ( ) const

inline

Returns a Windows GUID from a QUuid.

Warning: This method is only for Windows platforms.

constexpr bool QUuid::operator!= ( const GUID & guid ) const

inlineconstexpr

Returns true if this QUid is not equal to the given guid, otherwise returns false.

constexpr bool QUuid::operator!= ( const QUuid & other ) const

inlineconstexpr

Returns true if this QUuid and the other are different, otherwise returns false.

bool QUuid::operator< ( const QUuid & other ) const

Returns true if this QUuid has the same variant field as other and is lexicographically before other. If the other QUuid has a different variant field, the return value is determined by comparing the two variants.

See also: variant()

constexpr QUuid & QUuid::operator= ( const GUID & guid )

inlineconstexpr

Copy assigns from other and returns a reference to this object. This method only exists on Windows platforms.

constexpr bool QUuid::operator== ( const GUID & guid ) const

inlineconstexpr

Returns true if this QUUid is equal to the given guid, otherwise returns false.

constexpr bool QUuid::operator== ( const QUuid & other ) const

inlineconstexpr

Returns true if this QUuid and other are identical, otherwise returns false.

bool QUuid::operator> ( const QUuid & other ) const

Returns true if this QUuid has the same variant field as other and is lexicographically after the other. If other has a different variant field the return value is determined by comparing the two variants.

See also: variant()

QByteArray QUuid::toByteArray ( ) const

Returns the binary representation of this QUuid. The byte array is formatted as five hex fields separated by '-' and enclosed in curly braces, i.e., "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}" where 'x' is a hex digit. From left to right, the five hex fields are obtained from the four public data members in QUuid as follows:

Field #	Source
1	data1
2	data2
3	data3
4	data4[0] .. data4[1]
5	data4[2] .. data4[7]

QByteArray QUuid::toRfc4122 ( ) const

Returns the binary representation of this QUuid. The byte array is in big endian format, and formatted according to RFC 4122, section 4.1.2 - "Layout and byte order".

The order is as follows:

Field #	Source
1	data1
2	data2
3	data3
4	data4[0] .. data4[7]

QString QUuid::toString ( ) const

Returns the string representation of this QUuid. The string is formatted as five hex fields separated by '-' and enclosed in curly braces, i.e., "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}" where 'x' is a hex digit. From left to right, the five hex fields are obtained from the four public data members in QUuid as follows.

Field #	Source
1	data1
2	data2
3	data3
4	data4[0] .. data4[1]
5	data4[2] .. data4[7]

QUuid::Variant QUuid::variant ( ) const

Returns the value in the variant field of the UUID. If the return value is QUuid::DCE, call version() to see which layout it uses. The null UUID is considered to be of an unknown variant.

See also: version()

QUuid::Version QUuid::version ( ) const

Returns the version field of the UUID, if the UUID's variant field is QUuid::DCE. Otherwise it returns QUuid::VerUnknown.

See also: variant()

Friends And Related Function Documentation

QDataStream & operator<<	(	QDataStream &	stream,
		const QUuid &	id
	)

QDataStream & operator>>	(	QDataStream &	stream,
		QUuid &	id
	)

Public Types

Public Methods

Static Public Methods

Related Functions

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Method Documentation

Friends And Related Function Documentation