php-doc-en/reference/array/functions/natsort.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.natsort" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>natsort</refname>
  <refpurpose>Sort an array using a "natural order" algorithm</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>natsort</methodname>
   <methodparam><type>array</type><parameter role="reference">array</parameter></methodparam>
  </methodsynopsis>
  <para>
   This function implements a sort algorithm that orders alphanumeric strings
   in the way a human being would while maintaining key/value associations.
   This is described as a "natural ordering".  An example of the difference
   between this algorithm and the regular computer string sorting algorithms
   (used in <function>sort</function>) can be seen in the example below.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>array</parameter></term>
     <listitem>
      <para>
       The input array.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry>5.2.10</entry>
      <entry>
       Zero padded numeric strings (e.g., '00005') now essentially ignore the 0 padding.
      </entry>
     </row>
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>natsort</function> examples demonstrating basic usage</title>
    <programlisting role="php">
<![CDATA[
<?php
$array1 = $array2 = array("img12.png", "img10.png", "img2.png", "img1.png");

asort($array1);
echo "Standard sorting\n";
print_r($array1);

natsort($array2);
echo "\nNatural order sorting\n";
print_r($array2);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Standard sorting
Array
(
    [3] => img1.png
    [1] => img10.png
    [0] => img12.png
    [2] => img2.png
)

Natural order sorting
Array
(
    [3] => img1.png
    [2] => img2.png
    [1] => img10.png
    [0] => img12.png
)
]]>
    </screen>
    <para>
     For more information see: Martin Pool's <link
     xlink:href="&url.strnatcmp;">Natural Order String Comparison</link>
     page.
    </para>
   </example>
   <example>
    <title><function>natsort</function> examples demonstrating potential gotchas</title>
    <programlisting role="php">
<![CDATA[
<?php
echo "Negative numbers\n";
$negative = array('-5','3','-2','0','-1000','9','1');
print_r($negative);
natsort($negative);
print_r($negative);

echo "Zero padding\n";
$zeros = array('09', '8', '10', '009', '011', '0'); 
print_r($zeros);
natsort($zeros);
print_r($zeros);

echo "Other characters interfering\n";
$images_oops = array('image_1.jpg','image_12.jpg', 'image_21.jpg', 'image_4.jpg');
print_r($images_oops);
natsort($images_oops);
print_r($images_oops);

echo "Sort by keys\n";
$smoothie = array('orange' => 1, 'apple' => 1, 'yogurt' => 4, 'banana' => 4);
print_r($smoothie);
uksort( $smoothie, 'strnatcmp');
print_r($smoothie);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Negative numbers
Array
(
    [0] => -5
    [1] => 3
    [2] => -2
    [3] => 0
    [4] => -1000
    [5] => 9
    [6] => 1
)
Array
(
    [2] => -2
    [0] => -5
    [4] => -1000
    [3] => 0
    [6] => 1
    [1] => 3
    [5] => 9
)

Zero padding
Array
(
    [0] => 09
    [1] => 8
    [2] => 10
    [3] => 009
    [4] => 011
    [5] => 0
)
Array
(
    [5] => 0
    [1] => 8
    [3] => 009
    [0] => 09
    [2] => 10
    [4] => 011
)

Other characters interfering
Array
(
    [0] => image_1.jpg
    [1] => image_12.jpg
    [2] => image_21.jpg
    [3] => image_4.jpg
)
Array
(
    [0] => image_1.jpg
    [3] => image_4.jpg
    [1] => image_12.jpg
    [2] => image_21.jpg
)

Sort by keys
Array
(
    [orange] => 1
    [apple]  => 1
    [yogurt] => 4
    [banana] => 4
)
Array
(
    [apple]  => 1
    [banana] => 4
    [orange] => 1
    [yogurt] => 4
)
]]>
    </screen>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>natcasesort</function></member>
    <member>&seealso.array.sorting;</member>
    <member><function>strnatcmp</function></member>
    <member><function>strnatcasecmp</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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