glib-hash-tables.html

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</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>key</code></em>&#160;:</span></p></td>
<td> a key to insert.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>value</code></em>&#160;:</span></p></td>
<td> the value to associate with the key.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id3289656"></a><h3>
<a name="g-hash-table-size"></a>g_hash_table_size ()</h3>
<a class="indexterm" name="id3289670"></a><pre class="programlisting"><a class="link" href="glib-Basic-Types.html#guint">guint</a>               g_hash_table_size                   (<a class="link" href="glib-Hash-Tables.html#GHashTable">GHashTable</a> *hash_table);</pre>
<p>
Returns the number of elements contained in the <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.</p>
<p>

</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
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<td><p><span class="term"><em class="parameter"><code>hash_table</code></em>&#160;:</span></p></td>
<td> a <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span>&#160;:</span></p></td>
<td> the number of key/value pairs in the <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id3289754"></a><h3>
<a name="g-hash-table-lookup"></a>g_hash_table_lookup ()</h3>
<a class="indexterm" name="id3289767"></a><pre class="programlisting"><a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a>            g_hash_table_lookup                 (<a class="link" href="glib-Hash-Tables.html#GHashTable">GHashTable</a> *hash_table,
                                                         <a class="link" href="glib-Basic-Types.html#gconstpointer">gconstpointer</a> key);</pre>
<p>
Looks up a key in a <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>. Note that this function cannot
distinguish between a key that is not present and one which is present
and has the value <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>. If you need this distinction, use
<a class="link" href="glib-Hash-Tables.html#g-hash-table-lookup-extended"><code class="function">g_hash_table_lookup_extended()</code></a>.</p>
<p>

</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>hash_table</code></em>&#160;:</span></p></td>
<td> a <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>key</code></em>&#160;:</span></p></td>
<td> the key to look up.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span>&#160;:</span></p></td>
<td> the associated value, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> if the key is not found.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id3289899"></a><h3>
<a name="g-hash-table-lookup-extended"></a>g_hash_table_lookup_extended ()</h3>
<a class="indexterm" name="id3289912"></a><pre class="programlisting"><a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            g_hash_table_lookup_extended        (<a class="link" href="glib-Hash-Tables.html#GHashTable">GHashTable</a> *hash_table,
                                                         <a class="link" href="glib-Basic-Types.html#gconstpointer">gconstpointer</a> lookup_key,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> *orig_key,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> *value);</pre>
<p>
Looks up a key in the <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>, returning the original key and the
associated value and a <a class="link" href="glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> which is <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the key was found. This
is useful if you need to free the memory allocated for the original key,
for example before calling <a class="link" href="glib-Hash-Tables.html#g-hash-table-remove"><code class="function">g_hash_table_remove()</code></a>.</p>
<p>

</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>hash_table</code></em>&#160;:</span></p></td>
<td> a <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>lookup_key</code></em>&#160;:</span></p></td>
<td> the key to look up.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>orig_key</code></em>&#160;:</span></p></td>
<td> returns the original key.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>value</code></em>&#160;:</span></p></td>
<td> returns the value associated with the key.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span>&#160;:</span></p></td>
<td> <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the key was found in the <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id3290105"></a><h3>
<a name="g-hash-table-foreach"></a>g_hash_table_foreach ()</h3>
<a class="indexterm" name="id3290118"></a><pre class="programlisting">void                g_hash_table_foreach                (<a class="link" href="glib-Hash-Tables.html#GHashTable">GHashTable</a> *hash_table,
                                                         <a class="link" href="glib-Hash-Tables.html#GHFunc">GHFunc</a> func,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> user_data);</pre>
<p>
Calls the given function for each of the key/value pairs in the
<a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.  The function is passed the key and value of each
pair, and the given <em class="parameter"><code>user_data</code></em> parameter.  The hash table may not
be modified while iterating over it (you can't add/remove
items). To remove all items matching a predicate, use
<a class="link" href="glib-Hash-Tables.html#g-hash-table-foreach-remove"><code class="function">g_hash_table_foreach_remove()</code></a>.
</p>
<p>
See <a class="link" href="glib-Hash-Tables.html#g-hash-table-find"><code class="function">g_hash_table_find()</code></a> for performance caveats for linear
order searches in contrast to <a class="link" href="glib-Hash-Tables.html#g-hash-table-lookup"><code class="function">g_hash_table_lookup()</code></a>.</p>
<p>

</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>hash_table</code></em>&#160;:</span></p></td>
<td> a <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>func</code></em>&#160;:</span></p></td>
<td> the function to call for each key/value pair.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em>&#160;:</span></p></td>
<td> user data to pass to the function.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id3290275"></a><h3>
<a name="g-hash-table-find"></a>g_hash_table_find ()</h3>
<a class="indexterm" name="id3290291"></a><pre class="programlisting"><a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a>            g_hash_table_find                   (<a class="link" href="glib-Hash-Tables.html#GHashTable">GHashTable</a> *hash_table,
                                                         <a class="link" href="glib-Hash-Tables.html#GHRFunc">GHRFunc</a> predicate,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> user_data);</pre>
<p>
Calls the given function for key/value pairs in the <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a> until
<em class="parameter"><code>predicate</code></em> returns <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>.  The function is passed the key and value of
each pair, and the given <em class="parameter"><code>user_data</code></em> parameter. The hash table may not
be modified while iterating over it (you can't add/remove items).
</p>
<p>
Note, that hash tables are really only optimized for forward lookups,
i.e. <a class="link" href="glib-Hash-Tables.html#g-hash-table-lookup"><code class="function">g_hash_table_lookup()</code></a>.
So code that frequently issues <a class="link" href="glib-Hash-Tables.html#g-hash-table-find"><code class="function">g_hash_table_find()</code></a> or
<a class="link" href="glib-Hash-Tables.html#g-hash-table-foreach"><code class="function">g_hash_table_foreach()</code></a> (e.g. in the order of once per every entry in a
hash table) should probably be reworked to use additional or different
data structures for reverse lookups (keep in mind that an O(n) find/foreach
operation issued for all n values in a hash table ends up needing O(n*n)
operations).</p>
<p>

</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>hash_table</code></em>&#160;:</span></p></td>
<td> a <a class="link" href="glib-Hash-Tables.html#GHashTable"><span class="type">GHashTable</span></a>.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>predicate</code></em>&#160;:</span></p></td>
<td>  function to test the key/value pairs for a certain property.
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em>&#160;:</span></p></td>
<td>  user data to pass to the function.
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span>&#160;:</span></p></td>
<td> The value of the first key/value pair is returned, for which