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

#include <quuid.h>

Public Types
enum	Variant { VarUnknown =-1 , NCS = 0 , DCE = 2 , Microsoft = 6 , Reserved = 7 }

enum	Version { VerUnknown =-1 , Time = 1 , EmbeddedPOSIX = 2 , Md5 = 3 , Name = Md5 , Random = 4 , Sha1 = 5 }

enum	StringFormat { WithBraces = 0 , WithoutBraces = 1 , Id128 = 3 }

Public Member Functions
constexpr	QUuid () noexcept

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

	QUuid (QAnyStringView string) noexcept

QString	toString (StringFormat mode=WithBraces) const

QByteArray	toByteArray (StringFormat mode=WithBraces) const

QByteArray	toRfc4122 () const

bool	isNull () const noexcept

constexpr bool	operator== (const QUuid &orig) const noexcept

constexpr bool	operator!= (const QUuid &orig) const noexcept

bool	operator< (const QUuid &other) const noexcept

bool	operator> (const QUuid &other) const noexcept

QUuid::Variant	variant () const noexcept

QUuid::Version	version () const noexcept

Static Public Member Functions
static QUuid	fromString (QAnyStringView string) noexcept

static QUuid	fromRfc4122 (QByteArrayView) noexcept

static QUuid	createUuid ()

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

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

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

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

Public Attributes
uint	data1

ushort	data2

ushort	data3

uchar	data4 [8]

Related Functions
(Note that these are not member functions.)
QDataStream &	operator<< (QDataStream &s, const QUuid &id)

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

bool	operator<= (const QUuid &lhs, const QUuid &rhs)

bool	operator>= (const QUuid &lhs, const QUuid &rhs)

QDebug	operator<< (QDebug dbg, const QUuid &id)

size_t	qHash (const QUuid &uuid, size_t seed) noexcept

Detailed Description

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

\inmodule QtCore

\reentrant

Using {U}niversally {U}nique {ID}entifiers (UUID) is a standard way to uniquely identify entities in a distributed computing environment. A UUID is a 16-byte (128-bit) number generated by some algorithm that is meant to guarantee that the UUID will be unique in the distributed computing environment where it is used. The acronym GUID is often used instead, {G}lobally {U}nique {ID}entifiers, but it refers to the same thing.

\target Variant field Actually, the GUID is one {variant} of UUID. Multiple variants are in use. Each UUID contains a bit field that specifies which type (variant) of UUID it is. Call variant() to discover which type of UUID an instance of QUuid contains. It extracts the three most significant bits of byte 8 of the 16 bytes. In QUuid, byte 8 is {QUuid::data4[0]}. If you create instances of QUuid using the constructor that accepts all the numeric values as parameters, use the following table to set the three most significant bits of parameter {b1}, which becomes {QUuid::data4[0]} and contains the variant field in its three most significant bits. In the table, 'x' means {don't care}.

\table \header

msb0
msb1
msb2
Variant

\row

0
x
x
NCS (Network Computing System)

\row

1
0
x
DCE (Distributed Computing Environment)

\row

1
1
0
Microsoft (GUID)

\row

1
1
1
Reserved for future expansion

\endtable

\target Version field 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.

\table \header

msb0
msb1
msb2
msb3
Version

\row

0
0
0
1
Time

\row

0
0
1
0
Embedded POSIX

\row

0
0
1
1
Md5(Name)

\row

0
1
0
0
Random

\row

0
1
0
1
Sha1

\endtable

The field layouts for the DCE versions listed in the table above are specified in the \l{RFC 4122} {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 \l{http://en.wikipedia.org/wiki/Universally_Unique_Identifier#Random_UUID_probability_of_duplicates} {a {very} small chance}.

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

Definition at line 66 of file quuid.h.

Member Enumeration Documentation

◆ StringFormat

enum QUuid::StringFormat

Since: 5.11

This enum is used by toString(StringFormat) to control the formatting of the string representation. The possible values are:

\value WithBraces The default, toString() will return five hex fields, separated by dashes and surrounded by braces. Example: {00000000-0000-0000-0000-000000000000}. \value WithoutBraces Only the five dash-separated fields, without the braces. Example: 00000000-0000-0000-0000-000000000000. \value Id128 Only the hex digits, without braces or dashes. Note that QUuid cannot parse this back again as input.

Enumerator
WithBraces
WithoutBraces
Id128

Definition at line 88 of file quuid.h.

◆ Variant

enum QUuid::Variant

This enum defines the values used in the \l{Variant field} {variant field} of the UUID. The value in the variant field determines the layout of the 128-bit value.

\value VarUnknown Variant is unknown \value NCS Reserved for NCS (Network Computing System) backward compatibility \value DCE Distributed Computing Environment, the scheme used by QUuid \value Microsoft Reserved for Microsoft backward compatibility (GUID) \value Reserved Reserved for future definition

Enumerator
VarUnknown
NCS
DCE
Microsoft
Reserved

Definition at line 70 of file quuid.h.

◆ Version

enum QUuid::Version

This enum defines the values used in the \l{Version field} {version field} of the UUID. The version field is meaningful only if the value in the \l{Variant field} {variant field} is QUuid::DCE.

\value VerUnknown Version is unknown \value Time Time-based, by using timestamp, clock sequence, and MAC network card address (if available) for the node sections \value EmbeddedPOSIX DCE Security version, with embedded POSIX UUIDs \value Name Name-based, by using values from a name for all sections \value Md5 Alias for Name \value Random Random-based, by using random numbers for all sections \value Sha1

Enumerator
VerUnknown
Time
EmbeddedPOSIX
Md5
Name
Random
Sha1

Definition at line 78 of file quuid.h.

Constructor & Destructor Documentation

◆ QUuid() [1/3]

QUuid::QUuid ( )

inlineconstexprnoexcept

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

Definition at line 94 of file quuid.h.

◆ QUuid() [2/3]

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

inlineconstexprnoexcept

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

Example:

Definition at line 96 of file quuid.h.

◆ QUuid() [3/3]

QUuid::QUuid ( QAnyStringView text )

inlineexplicitnoexcept

Creates a QUuid object from the string text, which must be formatted as five hex fields separated by '-', e.g., "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}" where each 'x' is a hex digit. The curly braces shown here are optional, but it is normal to include them. If the conversion fails, a null UUID is created. See toString() for an explanation of how the five hex fields map to the public data members in QUuid.

Note: In Qt versions prior to 6.3, this constructor was an overload set consisting of QString, QByteArray and {const char*} instead of one constructor taking QAnyStringView.

See also: toString(), QUuid()

Definition at line 100 of file quuid.h.

Member Function Documentation

◆ createUuid()

QUuid QUuid::createUuid ( )

static

On any platform other than Windows, this function returns a new UUID with variant QUuid::DCE and version QUuid::Random. On Windows, a GUID is generated using the Windows API and will be of the type that the API decides to create.

See also: variant(), version()

Definition at line 936 of file quuid.cpp.

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◆ createUuidV3() [1/2]

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

static

Since: 5.0

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

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

Definition at line 482 of file quuid.cpp.

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◆ createUuidV3() [2/2]

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

inlinestatic

Since: 5.0

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

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

Definition at line 176 of file quuid.h.

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◆ createUuidV5() [1/2]

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

static

Since: 5.0

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

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

Definition at line 488 of file quuid.cpp.

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◆ createUuidV5() [2/2]

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

inlinestatic

Since: 5.0

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

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

Definition at line 182 of file quuid.h.

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◆ fromRfc4122()

QUuid QUuid::fromRfc4122 ( QByteArrayView bytes )

staticnoexcept

Creates a QUuid object from the binary representation of the UUID, as specified by RFC 4122 section 4.1.2. See toRfc4122() for a further explanation of the order of bytes required.

The byte array accepted is NOT a human readable format.

If the conversion fails, a null UUID is created.

Note: In Qt versions prior to 6.3, this function took QByteArray, not QByteArrayView.

Since: 4.8

See also: toRfc4122(), QUuid()

Definition at line 509 of file quuid.cpp.

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◆ fromString()

QUuid QUuid::fromString ( QAnyStringView string )

staticnoexcept

Since: 5.10

Creates a QUuid object from the string string, which must be formatted as five hex fields separated by '-', e.g., "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}" where each 'x' is a hex digit. The curly braces shown here are optional, but it is normal to include them. If the conversion fails, a null UUID is returned. See toString() for an explanation of how the five hex fields map to the public data members in QUuid.

Note: In Qt versions prior to 6.3, this function was an overload set consisting of QStringView and QLatin1String instead of one function taking QAnyStringView.

See also: toString(), QUuid()

Definition at line 437 of file quuid.cpp.

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◆ isNull()

bool QUuid::isNull ( ) const

noexcept

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

Definition at line 757 of file quuid.cpp.

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◆ operator!=()

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

inlineconstexprnoexcept

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

Returns true if this UUID is not equal to the Windows GUID guid; otherwise returns false.

Definition at line 132 of file quuid.h.

◆ operator<()

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

noexcept

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

See also: variant()

Definition at line 850 of file quuid.cpp.

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◆ operator==()

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

inlineconstexprnoexcept

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

Returns true if this UUID is equal to the Windows GUID guid; otherwise returns false.

Definition at line 119 of file quuid.h.

◆ operator>()

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

noexcept

Returns true if this QUuid has the same \l{Variant field} {variant field} as the other QUuid and is lexicographically {after} the other QUuid. If the other QUuid has a different variant field, the return value is determined by comparing the two \l{QUuid::Variant} {variants}.

See also: variant()

Definition at line 877 of file quuid.cpp.

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◆ toByteArray()

QByteArray QUuid::toByteArray ( QUuid::StringFormat mode = WithBraces ) const

Since: 5.11

Returns the string representation of this QUuid, with the formattiong controlled by the mode parameter. From left to right, the five hex fields are obtained from the four public data members in QUuid as follows:

\table \header

Field #
Source

\row

1
data1

\row

2
data2

\row

3
data3

\row

4
data4[0] .. data4[1]

\row

5
data4[2] .. data4[7]

\endtable

Definition at line 624 of file quuid.cpp.

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◆ toRfc4122()

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:

\table \header

Field #
Source

\row

1
data1

\row

2
data2

\row

3
data3

\row

4
data4[0] .. data4[7]

\endtable

Since: 4.8

Definition at line 664 of file quuid.cpp.

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◆ toString()

QString QUuid::toString ( QUuid::StringFormat mode = WithBraces ) const

Since: 5.11

Returns the string representation of this QUuid, with the formattiong controlled by the mode parameter. From left to right, the five hex fields are obtained from the four public data members in QUuid as follows:

\table \header

Field #
Source

\row

1
data1

\row

2
data2

\row

3
data3

\row

4
data4[0] .. data4[1]

\row

5
data4[2] .. data4[7]

\endtable

Definition at line 583 of file quuid.cpp.

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◆ variant()

QUuid::Variant QUuid::variant ( ) const

noexcept

Returns the value in the \l{Variant field} {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()

Definition at line 806 of file quuid.cpp.

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◆ version()

QUuid::Version QUuid::version ( ) const

noexcept

Returns the \l{Version field} {version field} of the UUID, if the UUID's \l{Variant field} {variant field} is QUuid::DCE. Otherwise it returns QUuid::VerUnknown.

See also: variant()

Definition at line 827 of file quuid.cpp.

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Friends And Related Function Documentation

◆ operator<<() [1/2]

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

Definition at line 690 of file quuid.cpp.

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◆ operator<<() [2/2]

QDebug operator<<	(	QDebug	dbg,
		const QUuid &	id
	)

Definition at line 969 of file quuid.cpp.

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◆ operator<=()

bool operator<=	(	const QUuid &	lhs,
		const QUuid &	rhs
	)

Since: 5.5

Returns true if lhs has the same \l{Variant field} {variant field} as rhs and is lexicographically {not after} rhs. If rhs has a different variant field, the return value is determined by comparing the two \l{QUuid::Variant} {variants}.

See also: {QUuid::}{variant()}

Definition at line 216 of file quuid.h.

◆ operator>=()

bool operator>=	(	const QUuid &	lhs,
		const QUuid &	rhs
	)

Since: 5.5

Returns true if lhs has the same \l{Variant field} {variant field} as rhs and is lexicographically {not before} rhs. If rhs has a different variant field, the return value is determined by comparing the two \l{QUuid::Variant} {variants}.

See also: {QUuid::}{variant()}

Definition at line 218 of file quuid.h.

◆ operator>>()

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

Definition at line 723 of file quuid.cpp.

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◆ qHash()

size_t qHash	(	const QUuid &	uuid,
		size_t	seed
	)

Since: 5.0

Returns a hash of the UUID uuid, using seed to seed the calculation.

Definition at line 982 of file quuid.cpp.

Member Data Documentation

◆ data1

uint QUuid::data1

Definition at line 197 of file quuid.h.

◆ data2

ushort QUuid::data2

Definition at line 198 of file quuid.h.

◆ data3

ushort QUuid::data3

Definition at line 199 of file quuid.h.

◆ data4

uchar QUuid::data4[8]

Definition at line 200 of file quuid.h.

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

src/corelib/plugin/quuid.h
src/corelib/plugin/quuid.cpp

Public Types

Public Member Functions

Static Public Member Functions

Public Attributes

Related Functions

Detailed Description

Member Enumeration Documentation

◆ StringFormat

◆ Variant

◆ Version

Constructor & Destructor Documentation

◆ QUuid() [1/3]

◆ QUuid() [2/3]

◆ QUuid() [3/3]

Member Function Documentation

◆ createUuid()

◆ createUuidV3() [1/2]

◆ createUuidV3() [2/2]

◆ createUuidV5() [1/2]

◆ createUuidV5() [2/2]

◆ fromRfc4122()

◆ fromString()

◆ isNull()

◆ operator!=()

◆ operator<()

◆ operator==()

◆ operator>()

◆ toByteArray()

◆ toRfc4122()

◆ toString()

◆ variant()

◆ version()

Friends And Related Function Documentation

◆ operator<<() [1/2]

◆ operator<<() [2/2]

◆ operator<=()

◆ operator>=()

◆ operator>>()

◆ qHash()

Member Data Documentation

◆ data1

◆ data2

◆ data3

◆ data4