<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.srand" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>srand</refname>
  <refpurpose>Seed the random number generator</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
   <methodsynopsis>
    <type>void</type><methodname>srand</methodname>
    <methodparam choice="opt"><type>int</type><parameter>seed</parameter></methodparam>
   </methodsynopsis>
  <para>
   Seeds the random number generator with <parameter>seed</parameter>
   or with a random value if no <parameter>seed</parameter> is given.
  </para>

  &note.randomseed;

 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>seed</parameter></term>
     <listitem>
      <para>
       Optional seed value
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.void;
  </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>Since 4.2.0</entry>
       <entry>
        The <parameter>seed</parameter> becomes optional
        and defaults to a random value if omitted.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>srand</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
// seed with microseconds
function make_seed()
{
  list($usec, $sec) = explode(' ', microtime());
  return (float) $sec + ((float) $usec * 100000);
}
srand(make_seed());
$randval = rand();
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>rand</function></member>
    <member><function>getrandmax</function></member>
    <member><function>mt_srand</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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