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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>GLib Reference Manual: Quarks</title>
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<td width="100%" align="left" class="shortcuts">
<a href="#" class="shortcut">Top</a><span id="nav_description"> <span class="dim">|</span>
<a href="#glib-Quarks.description" class="shortcut">Description</a></span>
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<div class="refentry">
<a name="glib-Quarks"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="glib-Quarks.top_of_page"></a>Quarks</span></h2>
<p>Quarks — a 2-way association between a string and a
unique integer identifier</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="glib-Quarks.functions"></a><h2>Functions</h2>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="glib-Quarks.html#G-DEFINE-QUARK:CAPS" title="G_DEFINE_QUARK()">G_DEFINE_QUARK</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>
</td>
<td class="function_name">
<a class="link" href="glib-Quarks.html#g-quark-from-string" title="g_quark_from_string ()">g_quark_from_string</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>
</td>
<td class="function_name">
<a class="link" href="glib-Quarks.html#g-quark-from-static-string" title="g_quark_from_static_string ()">g_quark_from_static_string</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *
</td>
<td class="function_name">
<a class="link" href="glib-Quarks.html#g-quark-to-string" title="g_quark_to_string ()">g_quark_to_string</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>
</td>
<td class="function_name">
<a class="link" href="glib-Quarks.html#g-quark-try-string" title="g_quark_try_string ()">g_quark_try_string</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *
</td>
<td class="function_name">
<a class="link" href="glib-Quarks.html#g-intern-string" title="g_intern_string ()">g_intern_string</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *
</td>
<td class="function_name">
<a class="link" href="glib-Quarks.html#g-intern-static-string" title="g_intern_static_string ()">g_intern_static_string</a> <span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="glib-Quarks.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody><tr>
<td class="typedef_keyword">typedef</td>
<td class="function_name"><a class="link" href="glib-Quarks.html#GQuark" title="GQuark">GQuark</a></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect1">
<a name="glib-Quarks.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include <glib.h>
</pre>
</div>
<div class="refsect1">
<a name="glib-Quarks.description"></a><h2>Description</h2>
<p>Quarks are associations between strings and integer identifiers.
Given either the string or the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> identifier it is possible to
retrieve the other.</p>
<p>Quarks are used for both <a class="link" href="glib-Datasets.html" title="Datasets">datasets</a> and
<a class="link" href="glib-Keyed-Data-Lists.html" title="Keyed Data Lists">keyed data lists</a>.</p>
<p>To create a new quark from a string, use <a class="link" href="glib-Quarks.html#g-quark-from-string" title="g_quark_from_string ()"><code class="function">g_quark_from_string()</code></a> or
<a class="link" href="glib-Quarks.html#g-quark-from-static-string" title="g_quark_from_static_string ()"><code class="function">g_quark_from_static_string()</code></a>.</p>
<p>To find the string corresponding to a given <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>, use
<a class="link" href="glib-Quarks.html#g-quark-to-string" title="g_quark_to_string ()"><code class="function">g_quark_to_string()</code></a>.</p>
<p>To find the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> corresponding to a given string, use
<a class="link" href="glib-Quarks.html#g-quark-try-string" title="g_quark_try_string ()"><code class="function">g_quark_try_string()</code></a>.</p>
<p>Another use for the string pool maintained for the quark functions
is string interning, using <a class="link" href="glib-Quarks.html#g-intern-string" title="g_intern_string ()"><code class="function">g_intern_string()</code></a> or
<a class="link" href="glib-Quarks.html#g-intern-static-string" title="g_intern_static_string ()"><code class="function">g_intern_static_string()</code></a>. An interned string is a canonical
representation for a string. One important advantage of interned
strings is that they can be compared for equality by a simple
pointer comparison, rather than using <code class="function">strcmp()</code>.</p>
</div>
<div class="refsect1">
<a name="glib-Quarks.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="G-DEFINE-QUARK:CAPS"></a><h3>G_DEFINE_QUARK()</h3>
<pre class="programlisting">#define G_DEFINE_QUARK(QN, q_n)</pre>
<p>A convenience macro which defines a function returning the
<a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> for the name <em class="parameter"><code>QN</code></em>
. The function will be named
<em class="parameter"><code><code class="function">q_n_quark()</code></code></em>
.</p>
<p>Note that the quark name will be stringified automatically
in the macro, so you shouldn't use double quotes.</p>
<div class="refsect3">
<a name="id-1.6.15.7.2.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>QN</p></td>
<td class="parameter_description"><p>the name to return a <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> for</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>q_n</p></td>
<td class="parameter_description"><p>prefix for the function name</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<p class="since">Since 2.34</p>
</div>
<hr>
<div class="refsect2">
<a name="g-quark-from-string"></a><h3>g_quark_from_string ()</h3>
<pre class="programlisting"><a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>
g_quark_from_string (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);</pre>
<p>Gets the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> identifying the given string. If the string does
not currently have an associated <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>, a new <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> is created,
using a copy of the string.</p>
<div class="refsect3">
<a name="id-1.6.15.7.3.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>string</p></td>
<td class="parameter_description"><p> a string. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="NULL is OK, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.6.15.7.3.6"></a><h4>Returns</h4>
<p> the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> identifying the string, or 0 if <em class="parameter"><code>string</code></em>
is <a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a></p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-quark-from-static-string"></a><h3>g_quark_from_static_string ()</h3>
<pre class="programlisting"><a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>
g_quark_from_static_string (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);</pre>
<p>Gets the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> identifying the given (static) string. If the
string does not currently have an associated <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>, a new <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>
is created, linked to the given string.</p>
<p>Note that this function is identical to <a class="link" href="glib-Quarks.html#g-quark-from-string" title="g_quark_from_string ()"><code class="function">g_quark_from_string()</code></a> except
that if a new <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> is created the string itself is used rather
than a copy. This saves memory, but can only be used if the string
will continue to exist until the program terminates. It can be used
with statically allocated strings in the main program, but not with
statically allocated memory in dynamically loaded modules, if you
expect to ever unload the module again (e.g. do not use this
function in GTK+ theme engines).</p>
<div class="refsect3">
<a name="id-1.6.15.7.4.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>string</p></td>
<td class="parameter_description"><p> a string. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="NULL is OK, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.6.15.7.4.7"></a><h4>Returns</h4>
<p> the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> identifying the string, or 0 if <em class="parameter"><code>string</code></em>
is <a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a></p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-quark-to-string"></a><h3>g_quark_to_string ()</h3>
<pre class="programlisting">const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *
g_quark_to_string (<em class="parameter"><code><a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> quark</code></em>);</pre>
<p>Gets the string associated with the given <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>.</p>
<div class="refsect3">
<a name="id-1.6.15.7.5.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>quark</p></td>
<td class="parameter_description"><p>a <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>.</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.6.15.7.5.6"></a><h4>Returns</h4>
<p> the string associated with the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a></p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-quark-try-string"></a><h3>g_quark_try_string ()</h3>
<pre class="programlisting"><a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>
g_quark_try_string (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);</pre>
<p>Gets the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> associated with the given string, or 0 if string is
<a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a> or it has no associated <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>.</p>
<p>If you want the GQuark to be created if it doesn't already exist,
use <a class="link" href="glib-Quarks.html#g-quark-from-string" title="g_quark_from_string ()"><code class="function">g_quark_from_string()</code></a> or <a class="link" href="glib-Quarks.html#g-quark-from-static-string" title="g_quark_from_static_string ()"><code class="function">g_quark_from_static_string()</code></a>.</p>
<div class="refsect3">
<a name="id-1.6.15.7.6.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>string</p></td>
<td class="parameter_description"><p> a string. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="NULL is OK, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.6.15.7.6.7"></a><h4>Returns</h4>
<p> the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> associated with the string, or 0 if <em class="parameter"><code>string</code></em>
is
<a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a> or there is no <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> associated with it</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="g-intern-string"></a><h3>g_intern_string ()</h3>
<pre class="programlisting">const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *
g_intern_string (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);</pre>
<p>Returns a canonical representation for <em class="parameter"><code>string</code></em>
. Interned strings
can be compared for equality by comparing the pointers, instead of
using <code class="function">strcmp()</code>.</p>
<div class="refsect3">
<a name="id-1.6.15.7.7.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>string</p></td>
<td class="parameter_description"><p> a string. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="NULL is OK, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.6.15.7.7.6"></a><h4>Returns</h4>
<p> a canonical representation for the string</p>
<p></p>
</div>
<p class="since">Since 2.10</p>
</div>
<hr>
<div class="refsect2">
<a name="g-intern-static-string"></a><h3>g_intern_static_string ()</h3>
<pre class="programlisting">const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *
g_intern_static_string (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);</pre>
<p>Returns a canonical representation for <em class="parameter"><code>string</code></em>
. Interned strings
can be compared for equality by comparing the pointers, instead of
using <code class="function">strcmp()</code>. <a class="link" href="glib-Quarks.html#g-intern-static-string" title="g_intern_static_string ()"><code class="function">g_intern_static_string()</code></a> does not copy the string,
therefore <em class="parameter"><code>string</code></em>
must not be freed or modified.</p>
<div class="refsect3">
<a name="id-1.6.15.7.8.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>string</p></td>
<td class="parameter_description"><p> a static string. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="NULL is OK, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.6.15.7.8.6"></a><h4>Returns</h4>
<p> a canonical representation for the string</p>
<p></p>
</div>
<p class="since">Since 2.10</p>
</div>
</div>
<div class="refsect1">
<a name="glib-Quarks.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GQuark"></a><h3>GQuark</h3>
<pre class="programlisting">typedef guint32 GQuark;
</pre>
<p>A GQuark is a non-zero integer which uniquely identifies a
particular string. A GQuark value of zero is associated to <a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a>.</p>
</div>
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