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  <refentry id="function.srand">
   <refnamediv>
    <refname>srand</refname>
    <refpurpose>Seed the random number generator</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
     <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>.
     Since PHP 4.2.0, the <parameter>seed</parameter>
     becomes optional and defaults to a random value if omitted.
    </para>
    <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>

    &note.randomseed;

    <simpara>
     See also:
     <function>rand</function>,
     <function>getrandmax</function>, and
     <function>mt_srand</function>.
    </simpara>    
   </refsect1>
  </refentry>

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