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

<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.array-rand" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_rand</refname>
  <refpurpose>Pick one or more random entries out of an array</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>array_rand</methodname>
   <methodparam><type>array</type><parameter>array</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>num</parameter><initializer>1</initializer></methodparam>
  </methodsynopsis>
  <para>
   Picks one or more random entries out of an array, and returns the
   key (or keys) of the random entries.
   It uses a pseudo random number generator that is not suitable for
   cryptographic purposes.
  </para>
 </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>num</parameter></term>
     <listitem>
      <para>
       Specifies how many entries should be picked.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   When picking only one entry, <function>array_rand</function> returns
   the key for a random entry. Otherwise, an array of keys for the random
   entries is returned. This is done so that random keys can be picked
   from the array as well as random values. Trying to pick more elements
   than there are in the array will result in an
   <constant>E_WARNING</constant> level error, and NULL will be returned.
  </para>
 </refsect1>
 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>5.2.10</entry>
       <entry>
        The resulting array of keys is no longer shuffled.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>array_rand</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$input = array("Neo", "Morpheus", "Trinity", "Cypher", "Tank");
$rand_keys = array_rand($input, 2);
echo $input[$rand_keys[0]] . "\n";
echo $input[$rand_keys[1]] . "\n";
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>shuffle</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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