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

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<refentry xml:id="function.sort" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>sort</refname>
  <refpurpose>Sort an array</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>sort</methodname>
   <methodparam><type>array</type><parameter role="reference">array</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>sort_flags</parameter><initializer>SORT_REGULAR</initializer></methodparam>
  </methodsynopsis>
  <para>
   This function sorts an array.  Elements will be arranged from
   lowest to highest when this function has completed.
  </para>
  &note.sort-unstable;
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>array</parameter></term>
     <listitem>
      <para>
       The input array.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>sort_flags</parameter></term>
     <listitem>
      <para>
       The optional second parameter <parameter>sort_flags</parameter>
       may be used to modify the sorting behavior using these values:
      </para>
      <para>
       Sorting type flags:
       <itemizedlist>
        <listitem>
         <simpara><constant>SORT_REGULAR</constant> - compare items normally;
         the details are described in the <link linkend="language.operators.comparison">comparison operators</link> section</simpara>
        </listitem>
        <listitem>
         <simpara><constant>SORT_NUMERIC</constant> - compare items numerically</simpara>
        </listitem>
        <listitem>
         <simpara><constant>SORT_STRING</constant> - compare items as strings</simpara>
        </listitem>
        <listitem>
         <simpara>
          <constant>SORT_LOCALE_STRING</constant> - compare items as
          strings, based on the current locale. It uses the locale,
          which can be changed using <function>setlocale</function>
         </simpara>
        </listitem>
        <listitem>
         <simpara>
          <constant>SORT_NATURAL</constant> - compare items as strings
          using "natural ordering" like <function>natsort</function>
         </simpara>
        </listitem>
        <listitem>
         <simpara>
          <constant>SORT_FLAG_CASE</constant> - can be combined
          (bitwise OR) with
          <constant>SORT_STRING</constant> or
          <constant>SORT_NATURAL</constant> to sort strings case-insensitively
         </simpara>
        </listitem>
       </itemizedlist>
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>sort</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php

$fruits = array("lemon", "orange", "banana", "apple");
sort($fruits);
foreach ($fruits as $key => $val) {
    echo "fruits[" . $key . "] = " . $val . "\n";
}

?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
fruits[0] = apple
fruits[1] = banana
fruits[2] = lemon
fruits[3] = orange
]]>
    </screen>
   </example>
  </para>
  <para>
   The fruits have been sorted in alphabetical order.
  </para>
  <para>
   <example>
    <title><function>sort</function> example using case-insensitive natural
    ordering</title>
    <programlisting role="php">
<![CDATA[
<?php

$fruits = array(
    "Orange1", "orange2", "Orange3", "orange20"
);
sort($fruits, SORT_NATURAL | SORT_FLAG_CASE);
foreach ($fruits as $key => $val) {
    echo "fruits[" . $key . "] = " . $val . "\n";
}

?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
fruits[0] = Orange1
fruits[1] = orange2
fruits[2] = Orange3
fruits[3] = orange20
]]>
    </screen>
   </example>
  </para>
  <para>
   The fruits have been sorted like <function>natcasesort</function>.
  </para>
 </refsect1>
 <refsect1 role="notes">
  &reftitle.notes;
  &note.no-key-association;
  <note>
   <simpara>
    Like most PHP sorting functions, <function>sort</function> uses an
    implementation of <link
    xlink:href="&url.wiki.quicksort;">Quicksort</link>.
    The pivot is chosen in the middle of the partition resulting in an optimal
    time for already sorted arrays. This is however an implementation detail you
    shouldn't rely on.
   </simpara>
  </note>
  <warning>
   <simpara>
    Be careful when sorting arrays with mixed types values because
    <function>sort</function> can produce unexpected results,
    if <parameter>sort_flags</parameter> is <constant>SORT_REGULAR</constant>,
   </simpara>
  </warning>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>asort</function></member>
    <member><function>rsort</function></member>
    <member>&seealso.array.sorting;</member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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