<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
<html><head><title>QUuid Class Reference</title><style>h3.fn,span.fn { margin-left: 1cm; text-indent: -1cm }
a:link { color: #004faf; text-decoration: none }
a:visited { color: #672967; text-decoration: none }
td.postheader { font-family: sans-serif }
tr.address { font-family: sans-serif }
body { background: #ffffff; color: black; }
</style></head><body><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr /><td align="left" valign="top" width="32"><img align="left" border="0" height="32" src="images/rb-logo.png" width="32" /></td><td width="1">  </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="modules.html"><font color="#004faf">Modules</font></a></td></table><h1 align="center">QUuid Class Reference<br /><sup><sup>[<a href="qtcore.html">QtCore</a> module]</sup></sup></h1><p>The QUuid class stores a Universally Unique Identifier (UUID).
<a href="#details">More...</a></p>
<h3>Types</h3><ul><li><div class="fn" />enum <b><a href="quuid.html#Variant-enum">Variant</a></b> { VarUnknown, NCS, DCE, Microsoft, Reserved }</li><li><div class="fn" />enum <b><a href="quuid.html#Version-enum">Version</a></b> { VerUnknown, Time, EmbeddedPOSIX, Name, Random }</li></ul><h3>Methods</h3><ul><li><div class="fn" /><b><a href="quuid.html#QUuid">__init__</a></b> (<i>self</i>)</li><li><div class="fn" /><b><a href="quuid.html#QUuid-2">__init__</a></b> (<i>self</i>, int <i>l</i>, int <i>w1</i>, int <i>w2</i>, str <i>b1</i>, str <i>b2</i>, str <i>b3</i>, str <i>b4</i>, str <i>b5</i>, str <i>b6</i>, str <i>b7</i>, str <i>b8</i>)</li><li><div class="fn" /><b><a href="quuid.html#QUuid-3">__init__</a></b> (<i>self</i>, QString)</li><li><div class="fn" /><b><a href="quuid.html#QUuid-4">__init__</a></b> (<i>self</i>, QByteArray)</li><li><div class="fn" /><b><a href="quuid.html#QUuid-5">__init__</a></b> (<i>self</i>, QUuid)</li><li><div class="fn" />bool <b><a href="quuid.html#isNull">isNull</a></b> (<i>self</i>)</li><li><div class="fn" />QByteArray <b><a href="quuid.html#toByteArray">toByteArray</a></b> (<i>self</i>)</li><li><div class="fn" />QByteArray <b><a href="quuid.html#toRfc4122">toRfc4122</a></b> (<i>self</i>)</li><li><div class="fn" />QString <b><a href="quuid.html#toString">toString</a></b> (<i>self</i>)</li><li><div class="fn" />Variant <b><a href="quuid.html#variant">variant</a></b> (<i>self</i>)</li><li><div class="fn" />Version <b><a href="quuid.html#version">version</a></b> (<i>self</i>)</li></ul><h3>Static Methods</h3><ul><li><div class="fn" />QUuid <b><a href="quuid.html#createUuid">createUuid</a></b> ()</li><li><div class="fn" />QUuid <b><a href="quuid.html#fromRfc4122">fromRfc4122</a></b> (QByteArray)</li></ul><h3>Special Methods</h3><ul><li><div class="fn" />bool <b><a href="quuid.html#__eq__">__eq__</a></b> (<i>self</i>, QUuid <i>orig</i>)</li><li><div class="fn" />bool <b><a href="quuid.html#__ge__">__ge__</a></b> (<i>self</i>, QUuid <i>other</i>)</li><li><div class="fn" />bool <b><a href="quuid.html#__gt__">__gt__</a></b> (<i>self</i>, QUuid <i>other</i>)</li><li><div class="fn" />bool <b><a href="quuid.html#__le__">__le__</a></b> (<i>self</i>, QUuid <i>other</i>)</li><li><div class="fn" />bool <b><a href="quuid.html#__lt__">__lt__</a></b> (<i>self</i>, QUuid <i>other</i>)</li><li><div class="fn" />bool <b><a href="quuid.html#__ne__">__ne__</a></b> (<i>self</i>, QUuid <i>orig</i>)</li><li><div class="fn" />str <b><a href="quuid.html#__repr__">__repr__</a></b> (<i>self</i>)</li></ul><a name="details" /><hr /><h2>Detailed Description</h2><p>The QUuid class stores a Universally Unique Identifier
(UUID).</p>
<p>Using <i>U</i>niversally <i>U</i>nique <i>ID</i>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, <i>G</i>lobally
<i>U</i>nique <i>ID</i>entifiers, but it refers to the same
thing.</p>
<a id="variant-field" name="variant-field" />
<p>Actually, the GUID is one <i>variant</i> of UUID. Multiple
variants are in use. Each UUID contains a bit field that specifies
which type (variant) of UUID it is. Call <a href="quuid.html#variant">variant</a>() to discover which type of UUID
an instance of QUuid contains. It extracts the three most
signifcant bits of byte 8 of the 16 bytes. In QUuid, byte 8 is
<tt>QUuid.data4[0]</tt>. 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 <tt>b1</tt>, which becomes <tt>QUuid.data4[0]</tt> and
contains the variant field in its three most significant bits. In
the table, 'x' means <i>don't care</i>.</p>
<table class="generic">
<thead>
<tr class="qt-style">
<th>msb0</th>
<th>msb1</th>
<th>msb2</th>
<th>Variant</th>
</tr>
</thead>
<tr class="odd" valign="top">
<td>0</td>
<td>x</td>
<td>x</td>
<td>NCS (Network Computing System)</td>
</tr>
<tr class="even" valign="top">
<td>1</td>
<td>0</td>
<td>x</td>
<td>DCE (Distributed Computing Environment)</td>
</tr>
<tr class="odd" valign="top">
<td>1</td>
<td>1</td>
<td>0</td>
<td>Microsoft (GUID)</td>
</tr>
<tr class="even" valign="top">
<td>1</td>
<td>1</td>
<td>1</td>
<td>Reserved for future expansion</td>
</tr>
</table>
<a id="version-field" name="version-field" />
<p>If <a href="quuid.html#variant">variant</a>() returns <a href="quuid.html#Variant-enum">QUuid.DCE</a>, the UUID also contains a
<i>version</i> field in the four most significant bits of
<tt>QUuid.data3</tt>, and you can call <a href="quuid.html#version">version</a>() 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 <tt>w2</tt>, which becomes <tt>QUuid.data3</tt> and
contains the version field in its four most significant bits.</p>
<table class="generic">
<thead>
<tr class="qt-style">
<th>msb0</th>
<th>msb1</th>
<th>msb2</th>
<th>msb3</th>
<th>Version</th>
</tr>
</thead>
<tr class="odd" valign="top">
<td>0</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>Time</td>
</tr>
<tr class="even" valign="top">
<td>0</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>Embedded POSIX</td>
</tr>
<tr class="odd" valign="top">
<td>0</td>
<td>0</td>
<td>1</td>
<td>1</td>
<td>Name</td>
</tr>
<tr class="even" valign="top">
<td>0</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>Random</td>
</tr>
</table>
<p>The field layouts for the DCE versions listed in the table above
are specified in the <a href="http://www.ietf.org/rfc/rfc4122.txt">Network Working Group UUID
Specification</a>.</p>
<p>Most platforms provide a tool for generating new UUIDs, e.g.
<tt>uuidgen</tt> and <tt>guidgen</tt>. You can also use <a href="quuid.html#createUuid">createUuid</a>(). UUIDs generated by
<a href="quuid.html#createUuid">createUuid</a>() are of the random
type. Their <a href="quuid.html#Version-enum">QUuid.Version</a>
bits are set to <a href="quuid.html#Version-enum">QUuid.Random</a>, and their <a href="quuid.html#Variant-enum">QUuid.Variant</a> bits are set to
<a href="quuid.html#Variant-enum">QUuid.DCE</a>. The rest of the
UUID is composed of random numbers. Theoretically, this means there
is a small chance that a UUID generated by <a href="quuid.html#createUuid">createUuid</a>() will not be unique. But it
is <a href="http://en.wikipedia.org/wiki/Universally_Unique_Identifier#Random_UUID_probability_of_duplicates">
a <i>very</i> small chance</a>.</p>
<p>UUIDs can be constructed from numeric values or from strings, or
using the static <a href="quuid.html#createUuid">createUuid</a>()
function. They can be converted to a string with <a href="quuid.html#toString">toString</a>(). UUIDs have a <a href="quuid.html#variant">variant</a>() and a <a href="quuid.html#version">version</a>(), and null UUIDs return true from
<a href="quuid.html#isNull">isNull</a>().</p>
<hr /><h2>Type Documentation</h2><h3 class="fn"><a name="Variant-enum" />QUuid.Variant</h3><p>This enum defines the values used in the <a href="quuid.html#variant-field">variant field</a> of the UUID. The value
in the variant field determines the layout of the 128-bit
value.</p>
<table class="valuelist">
<tr class="odd" valign="top">
<th class="tblConst">Constant</th>
<th class="tblval">Value</th>
<th class="tbldscr">Description</th>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.VarUnknown</tt></td>
<td class="topAlign"><tt>-1</tt></td>
<td class="topAlign">Variant is unknown</td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.NCS</tt></td>
<td class="topAlign"><tt>0</tt></td>
<td class="topAlign">Reserved for NCS (Network Computing System)
backward compatibility</td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.DCE</tt></td>
<td class="topAlign"><tt>2</tt></td>
<td class="topAlign">Distributed Computing Environment, the scheme
used by <a href="quuid.html">QUuid</a></td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.Microsoft</tt></td>
<td class="topAlign"><tt>6</tt></td>
<td class="topAlign">Reserved for Microsoft backward compatibility
(GUID)</td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.Reserved</tt></td>
<td class="topAlign"><tt>7</tt></td>
<td class="topAlign">Reserved for future definition</td>
</tr>
</table>
<h3 class="fn"><a name="Version-enum" />QUuid.Version</h3><p>This enum defines the values used in the <a href="quuid.html#version-field">version field</a> of the UUID. The
version field is meaningful only if the value in the <a href="quuid.html#variant-field">variant field</a> is <a href="quuid.html#Variant-enum">QUuid.DCE</a>.</p>
<table class="valuelist">
<tr class="odd" valign="top">
<th class="tblConst">Constant</th>
<th class="tblval">Value</th>
<th class="tbldscr">Description</th>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.VerUnknown</tt></td>
<td class="topAlign"><tt>-1</tt></td>
<td class="topAlign">Version is unknown</td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.Time</tt></td>
<td class="topAlign"><tt>1</tt></td>
<td class="topAlign">Time-based, by using timestamp, clock
sequence, and MAC network card address (if available) for the node
sections</td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.EmbeddedPOSIX</tt></td>
<td class="topAlign"><tt>2</tt></td>
<td class="topAlign">DCE Security version, with embedded POSIX
UUIDs</td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.Name</tt></td>
<td class="topAlign"><tt>3</tt></td>
<td class="topAlign">Name-based, by using values from a name for
all sections</td>
</tr>
<tr>
<td class="topAlign"><tt>QUuid.Random</tt></td>
<td class="topAlign"><tt>4</tt></td>
<td class="topAlign">Random-based, by using random numbers for all
sections</td>
</tr>
</table>
<hr /><h2>Method Documentation</h2><h3 class="fn"><a name="QUuid" />QUuid.__init__ (<i>self</i>)</h3><p>Creates the null UUID. <a href="quuid.html#toString">toString</a>() will output the null UUID as
"{00000000-0000-0000-0000-000000000000}".</p>
<h3 class="fn"><a name="QUuid-2" />QUuid.__init__ (<i>self</i>, int <i>l</i>, int <i>w1</i>, int <i>w2</i>, str <i>b1</i>, str <i>b2</i>, str <i>b3</i>, str <i>b4</i>, str <i>b5</i>, str <i>b6</i>, str <i>b7</i>, str <i>b8</i>)</h3><p>Creates a UUID with the value specified by the parameters,
<i>l</i>, <i>w1</i>, <i>w2</i>, <i>b1</i>, <i>b2</i>, <i>b3</i>,
<i>b4</i>, <i>b5</i>, <i>b6</i>, <i>b7</i>, <i>b8</i>.</p>
<p>Example:</p>
<pre class="cpp">
<span class="comment">// {67C8770B-44F1-410A-AB9A-F9B5446F13EE}</span>
<span class="type"><a href="quuid.html">QUuid</a></span> IID_MyInterface(<span class="number">0x67c8770b</span><span class="operator">,</span> <span class="number">0x44f1</span><span class="operator">,</span> <span class="number">0x410a</span><span class="operator">,</span> <span class="number">0xab</span><span class="operator">,</span> <span class="number">0x9a</span><span class="operator">,</span> <span class="number">0xf9</span><span class="operator">,</span> <span class="number">0xb5</span><span class="operator">,</span> <span class="number">0x44</span><span class="operator">,</span> <span class="number">0x6f</span><span class="operator">,</span> <span class="number">0x13</span><span class="operator">,</span> <span class="number">0xee</span>)
</pre>
<h3 class="fn"><a name="QUuid-3" />QUuid.__init__ (<i>self</i>, QString)</h3><p>Creates a <a href="quuid.html">QUuid</a> object from the string
<i>text</i>, which must be formatted as five hex fields separated
by '-', e.g., "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}" where '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 <a href="quuid.html#toString">toString</a>() for an
explanation of how the five hex fields map to the public data
members in <a href="quuid.html">QUuid</a>.</p>
<p><b>See also</b> <a href="quuid.html#toString">toString</a>() and
<a href="quuid.html#QUuid">QUuid</a>().</p>
<h3 class="fn"><a name="QUuid-4" />QUuid.__init__ (<i>self</i>, <a href="qbytearray.html">QByteArray</a>)</h3><h3 class="fn"><a name="QUuid-5" />QUuid.__init__ (<i>self</i>, <a href="quuid.html">QUuid</a>)</h3><p>Creates a <a href="quuid.html">QUuid</a> object from the
<a href="qbytearray.html">QByteArray</a> <i>text</i>, which must be
formatted as five hex fields separated by '-', e.g.,
"{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}" where '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
<a href="quuid.html#toByteArray">toByteArray</a>() for an
explanation of how the five hex fields map to the public data
members in <a href="quuid.html">QUuid</a>.</p>
<p>This function was introduced in Qt 4.8.</p>
<p><b>See also</b> <a href="quuid.html#toByteArray">toByteArray</a>() and <a href="quuid.html#QUuid">QUuid</a>().</p>
<h3 class="fn"><a name="createUuid" /><a href="quuid.html">QUuid</a> QUuid.createUuid ()</h3><p>On any platform other than Windows, this function returns a new
UUID with variant <a href="quuid.html#Variant-enum">QUuid.DCE</a>
and version <a href="quuid.html#Version-enum">QUuid.Random</a>. 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 (<a href="qtcore.html#qrand">qrand</a>(), which is seeded by <a href="qtcore.html#qsrand">qsrand</a>()) which is usually not of
cryptograhic quality, which means that the UUID can't be guaranteed
to be unique.</p>
<p>On a Windows platform, a GUID is generated, which almost
certainly <i>will</i> be unique, on this or any other system,
networked or not.</p>
<p><b>See also</b> <a href="quuid.html#variant">variant</a>() and
<a href="quuid.html#version">version</a>().</p>
<h3 class="fn"><a name="fromRfc4122" /><a href="quuid.html">QUuid</a> QUuid.fromRfc4122 (<a href="qbytearray.html">QByteArray</a>)</h3><p>Creates a <a href="quuid.html">QUuid</a> object from the binary
representation of the UUID given by <i>bytes</i>, as specified by
RFC 4122 section 4.1.2. See <a href="quuid.html#toRfc4122">toRfc4122</a>() for a further explanation of
the order of bytes required.</p>
<p>The byte array accepted is <i>not</i> a human readable
format.</p>
<p>If the conversion fails, a null UUID is created.</p>
<p>This function was introduced in Qt 4.8.</p>
<p><b>See also</b> <a href="quuid.html#toRfc4122">toRfc4122</a>()
and <a href="quuid.html#QUuid">QUuid</a>().</p>
<h3 class="fn"><a name="isNull" />bool QUuid.isNull (<i>self</i>)</h3><p>Returns true if this is the null UUID
{00000000-0000-0000-0000-000000000000}; otherwise returns
false.</p>
<h3 class="fn"><a name="toByteArray" /><a href="qbytearray.html">QByteArray</a> QUuid.toByteArray (<i>self</i>)</h3><p>Returns the binary representation of this <a href="quuid.html">QUuid</a>. 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 <a href="quuid.html">QUuid</a> as
follows:</p>
<table class="generic">
<thead>
<tr class="qt-style">
<th>Field #</th>
<th>Source</th>
</tr>
</thead>
<tr class="odd" valign="top">
<td>1</td>
<td>data1</td>
</tr>
<tr class="even" valign="top">
<td>2</td>
<td>data2</td>
</tr>
<tr class="odd" valign="top">
<td>3</td>
<td>data3</td>
</tr>
<tr class="even" valign="top">
<td>4</td>
<td>data4[0] .. data4[1]</td>
</tr>
<tr class="odd" valign="top">
<td>5</td>
<td>data4[2] .. data4[7]</td>
</tr>
</table>
<p>This function was introduced in Qt 4.8.</p>
<h3 class="fn"><a name="toRfc4122" /><a href="qbytearray.html">QByteArray</a> QUuid.toRfc4122 (<i>self</i>)</h3><p>Returns the binary representation of this <a href="quuid.html">QUuid</a>. The byte array is in big endian format, and
formatted according to RFC 4122, section 4.1.2 - "Layout and byte
order".</p>
<p>The order is as follows:</p>
<table class="generic">
<thead>
<tr class="qt-style">
<th>Field #</th>
<th>Source</th>
</tr>
</thead>
<tr class="odd" valign="top">
<td>1</td>
<td>data1</td>
</tr>
<tr class="even" valign="top">
<td>2</td>
<td>data2</td>
</tr>
<tr class="odd" valign="top">
<td>3</td>
<td>data3</td>
</tr>
<tr class="even" valign="top">
<td>4</td>
<td>data4[0] .. data4[7]</td>
</tr>
</table>
<p>This function was introduced in Qt 4.8.</p>
<h3 class="fn"><a name="toString" />QString QUuid.toString (<i>self</i>)</h3><p>Returns the string representation of this <a href="quuid.html">QUuid</a>. 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 <a href="quuid.html">QUuid</a> as
follows:</p>
<table class="generic">
<thead>
<tr class="qt-style">
<th>Field #</th>
<th>Source</th>
</tr>
</thead>
<tr class="odd" valign="top">
<td>1</td>
<td>data1</td>
</tr>
<tr class="even" valign="top">
<td>2</td>
<td>data2</td>
</tr>
<tr class="odd" valign="top">
<td>3</td>
<td>data3</td>
</tr>
<tr class="even" valign="top">
<td>4</td>
<td>data4[0] .. data4[1]</td>
</tr>
<tr class="odd" valign="top">
<td>5</td>
<td>data4[2] .. data4[7]</td>
</tr>
</table>
<h3 class="fn"><a name="variant" /><a href="quuid.html#Variant-enum">Variant</a> QUuid.variant (<i>self</i>)</h3><p>Returns the value in the <a href="quuid.html#variant-field">variant field</a> of the UUID. If the
return value is <a href="quuid.html#Variant-enum">QUuid.DCE</a>,
call <a href="quuid.html#version">version</a>() to see which layout
it uses. The null UUID is considered to be of an unknown
variant.</p>
<p><b>See also</b> <a href="quuid.html#version">version</a>().</p>
<h3 class="fn"><a name="version" /><a href="quuid.html#Version-enum">Version</a> QUuid.version (<i>self</i>)</h3><p>Returns the <a href="quuid.html#version-field">version field</a>
of the UUID, if the UUID's <a href="quuid.html#variant-field">variant field</a> is <a href="quuid.html#Variant-enum">QUuid.DCE</a>. Otherwise it returns
<a href="quuid.html#Version-enum">QUuid.VerUnknown</a>.</p>
<p><b>See also</b> <a href="quuid.html#variant">variant</a>().</p>
<h3 class="fn"><a name="__eq__" />bool QUuid.__eq__ (<i>self</i>, <a href="quuid.html">QUuid</a> <i>orig</i>)</h3><h3 class="fn"><a name="__ge__" />bool QUuid.__ge__ (<i>self</i>, <a href="quuid.html">QUuid</a> <i>other</i>)</h3><h3 class="fn"><a name="__gt__" />bool QUuid.__gt__ (<i>self</i>, <a href="quuid.html">QUuid</a> <i>other</i>)</h3><h3 class="fn"><a name="__le__" />bool QUuid.__le__ (<i>self</i>, <a href="quuid.html">QUuid</a> <i>other</i>)</h3><h3 class="fn"><a name="__lt__" />bool QUuid.__lt__ (<i>self</i>, <a href="quuid.html">QUuid</a> <i>other</i>)</h3><h3 class="fn"><a name="__ne__" />bool QUuid.__ne__ (<i>self</i>, <a href="quuid.html">QUuid</a> <i>orig</i>)</h3><h3 class="fn"><a name="__repr__" />str QUuid.__repr__ (<i>self</i>)</h3><address><hr /><div align="center"><table border="0" cellspacing="0" width="100%"><tr class="address"><td align="left" width="25%">PyQt 4.10.3 for X11</td><td align="center" width="50%">Copyright © <a href="http://www.riverbankcomputing.com">Riverbank Computing Ltd</a> and <a href="http://www.qtsoftware.com">Nokia</a> 2012</td><td align="right" width="25%">Qt 4.8.5</td></tr></table></div></address></body></html>
