usort closure example (patch by Benjamin Kuz)

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@325271 c90b9560-bf6c-de11-be94-00142212c4b1

reference/array/functions/usort.xml

@@ -207,6 +207,41 @@ foreach ($a as $item) {
 b
 c
 d
+]]>
+    </screen>
+   </example>
+   <example>
+    <title>
+     <function>usort</function> example using a <link linkend="functions.anonymous">closure</link>
+     to sort a multi-dimensional array
+    </title>
+    <programlisting role="php">
+<![CDATA[
+<?php
+$array[0] = array('key_a' => 'z', 'key_b' => 'c');
+$array[1] = array('key_a' => 'x', 'key_b' => 'b');
+$array[2] = array('key_a' => 'y', 'key_b' => 'a');
+
+function build_sorter($key) {
+    return function ($a, $b) use ($key) {
+        return strnatcmp($a[$key], $b[$key]);
+    };
+}
+
+usort($array, build_sorter('key_b'));
+
+foreach ($array as $item) {
+    echo $item['key_a'] . ', ' . $item['key_b'] . "\n";
+}
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+y, a
+x, b
+z, c
 ]]>
     </screen>
    </example>