docs/reference/glib/html/glib-Quarks.html

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  20 <th width="100%" align="center">GLib Reference Manual</th>
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  24 <a href="#glib-Quarks.synopsis" class="shortcut">Top</a>
  25                    |
  26                   <a href="#glib-Quarks.description" class="shortcut">Description</a>
  27 </td></tr>
  28 </table>
  29 <div class="refentry">
  30 <a name="glib-Quarks"></a><div class="titlepage"></div>
  31 <div class="refnamediv"><table width="100%"><tr>
  32 <td valign="top">
  33 <h2><span class="refentrytitle"><a name="glib-Quarks.top_of_page"></a>Quarks</span></h2>
  34 <p>Quarks — a 2-way association between a string and a
  35                     unique integer identifier</p>
  36 </td>
  37 <td valign="top" align="right"></td>
  38 </tr></table></div>
  39 <div class="refsynopsisdiv">
  40 <a name="glib-Quarks.synopsis"></a><h2>Synopsis</h2>
  41 <pre class="synopsis">
  42 #include &lt;glib.h&gt;
  43
  44 typedef             <a class="link" href="glib-Quarks.html#GQuark" title="GQuark">GQuark</a>;
  45 <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>              <a class="link" href="glib-Quarks.html#g-quark-from-string" title="g_quark_from_string ()">g_quark_from_string</a>                 (<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>);
  46 <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>              <a class="link" href="glib-Quarks.html#g-quark-from-static-string" title="g_quark_from_static_string ()">g_quark_from_static_string</a>          (<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>);
  47 const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *       <a class="link" href="glib-Quarks.html#g-quark-to-string" title="g_quark_to_string ()">g_quark_to_string</a>                   (<em class="parameter"><code><a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a> quark</code></em>);
  48 <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="returnvalue">GQuark</span></a>              <a class="link" href="glib-Quarks.html#g-quark-try-string" title="g_quark_try_string ()">g_quark_try_string</a>                  (<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>);
  49 const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *       <a class="link" href="glib-Quarks.html#g-intern-string" title="g_intern_string ()">g_intern_string</a>                     (<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>);
  50 const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="returnvalue">gchar</span></a> *       <a class="link" href="glib-Quarks.html#g-intern-static-string" title="g_intern_static_string ()">g_intern_static_string</a>              (<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>);
  51 </pre>
  52 </div>
  53 <div class="refsect1">
  54 <a name="glib-Quarks.description"></a><h2>Description</h2>
  55 <p>
  56 Quarks are associations between strings and integer identifiers.
  57 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
  58 retrieve the other.
  59 </p>
  60 <p>
  61 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>.
  62 </p>
  63 <p>
  64 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
  65 <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>.
  66 </p>
  67 <p>
  68 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
  69 <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>.
  70 </p>
  71 <p>
  72 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
  73 <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>.
  74 </p>
  75 <p>
  76 Another use for the string pool maintained for the quark functions
  77 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
  78 <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
  79 representation for a string. One important advantage of interned
  80 strings is that they can be compared for equality by a simple
  81 pointer comparison, rather than using <code class="function">strcmp()</code>.
  82 </p>
  83 </div>
  84 <div class="refsect1">
  85 <a name="glib-Quarks.details"></a><h2>Details</h2>
  86 <div class="refsect2">
  87 <a name="GQuark"></a><h3>GQuark</h3>
  88 <pre class="programlisting">typedef guint32 GQuark;
  89 </pre>
  90 <p>
  91 A GQuark is a non-zero integer which uniquely identifies a
  92 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>.
  93 </p>
  94 </div>
  95 <hr>
  96 <div class="refsect2">
  97 <a name="g-quark-from-string"></a><h3>g_quark_from_string ()</h3>
  98 <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>
  99 <p>
 100 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
 101 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,
 102 using a copy of the string.
 103 </p>
 104 <div class="variablelist"><table border="0">
 105 <col align="left" valign="top">
 106 <tbody>
 107 <tr>
 108 <td><p><span class="term"><em class="parameter"><code>string</code></em> :</span></p></td>
 109 <td>a string. <span class="annotation">[<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 110 </td>
 111 </tr>
 112 <tr>
 113 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 114 <td>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
 115 <a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a>.</td>
 116 </tr>
 117 </tbody>
 118 </table></div>
 119 </div>
 120 <hr>
 121 <div class="refsect2">
 122 <a name="g-quark-from-static-string"></a><h3>g_quark_from_static_string ()</h3>
 123 <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>
 124 <p>
 125 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
 126 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>
 127 is created, linked to the given string.
 128 </p>
 129 <p>
 130 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
 131 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
 132 than a copy. This saves memory, but can only be used if the string
 133 will <span class="emphasis"><em>always</em></span> exist. It can be used with
 134 statically allocated strings in the main program, but not with
 135 statically allocated memory in dynamically loaded modules, if you
 136 expect to ever unload the module again (e.g. do not use this
 137 function in GTK+ theme engines).
 138 </p>
 139 <div class="variablelist"><table border="0">
 140 <col align="left" valign="top">
 141 <tbody>
 142 <tr>
 143 <td><p><span class="term"><em class="parameter"><code>string</code></em> :</span></p></td>
 144 <td>a string. <span class="annotation">[<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 145 </td>
 146 </tr>
 147 <tr>
 148 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 149 <td>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
 150 <a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a>.</td>
 151 </tr>
 152 </tbody>
 153 </table></div>
 154 </div>
 155 <hr>
 156 <div class="refsect2">
 157 <a name="g-quark-to-string"></a><h3>g_quark_to_string ()</h3>
 158 <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>
 159 <p>
 160 Gets the string associated with the given <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>.
 161 </p>
 162 <div class="variablelist"><table border="0">
 163 <col align="left" valign="top">
 164 <tbody>
 165 <tr>
 166 <td><p><span class="term"><em class="parameter"><code>quark</code></em> :</span></p></td>
 167 <td>a <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>.</td>
 168 </tr>
 169 <tr>
 170 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 171 <td>the string associated with the <a class="link" href="glib-Quarks.html#GQuark" title="GQuark"><span class="type">GQuark</span></a>.</td>
 172 </tr>
 173 </tbody>
 174 </table></div>
 175 </div>
 176 <hr>
 177 <div class="refsect2">
 178 <a name="g-quark-try-string"></a><h3>g_quark_try_string ()</h3>
 179 <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>
 180 <p>
 181 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
 182 <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>.
 183 </p>
 184 <p>
 185 If you want the GQuark to be created if it doesn't already exist,
 186 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>.
 187 </p>
 188 <div class="variablelist"><table border="0">
 189 <col align="left" valign="top">
 190 <tbody>
 191 <tr>
 192 <td><p><span class="term"><em class="parameter"><code>string</code></em> :</span></p></td>
 193 <td>a string. <span class="annotation">[<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 194 </td>
 195 </tr>
 196 <tr>
 197 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 198 <td>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
 199 <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.</td>
 200 </tr>
 201 </tbody>
 202 </table></div>
 203 </div>
 204 <hr>
 205 <div class="refsect2">
 206 <a name="g-intern-string"></a><h3>g_intern_string ()</h3>
 207 <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>
 208 <p>
 209 Returns a canonical representation for <em class="parameter"><code>string</code></em>. Interned strings can
 210 be compared for equality by comparing the pointers, instead of using <code class="function">strcmp()</code>.
 211 </p>
 212 <div class="variablelist"><table border="0">
 213 <col align="left" valign="top">
 214 <tbody>
 215 <tr>
 216 <td><p><span class="term"><em class="parameter"><code>string</code></em> :</span></p></td>
 217 <td>a string. <span class="annotation">[<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 218 </td>
 219 </tr>
 220 <tr>
 221 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 222 <td>a canonical representation for the string</td>
 223 </tr>
 224 </tbody>
 225 </table></div>
 226 <p class="since">Since 2.10</p>
 227 </div>
 228 <hr>
 229 <div class="refsect2">
 230 <a name="g-intern-static-string"></a><h3>g_intern_static_string ()</h3>
 231 <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>
 232 <p>
 233 Returns a canonical representation for <em class="parameter"><code>string</code></em>. Interned strings can
 234 be compared for equality by comparing the pointers, instead of using <code class="function">strcmp()</code>.
 235 <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
 236 not be freed or modified.
 237 </p>
 238 <div class="variablelist"><table border="0">
 239 <col align="left" valign="top">
 240 <tbody>
 241 <tr>
 242 <td><p><span class="term"><em class="parameter"><code>string</code></em> :</span></p></td>
 243 <td>a static string. <span class="annotation">[<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 244 </td>
 245 </tr>
 246 <tr>
 247 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 248 <td>a canonical representation for the string</td>
 249 </tr>
 250 </tbody>
 251 </table></div>
 252 <p class="since">Since 2.10</p>
 253 </div>
 254 </div>
 255 </div>
 256 <div class="footer">
 257 <hr>
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