Notice: Undefined index: HTTP_X_FORWARDED_FOR Error in Function
<p>I'm getting Notice: Undefined index: HTTP_X_FORWARDED_FOR in the Function below:</p>

<pre><code>function _ip( )
{
    return ( preg_match( "/^([d]{1,3}).([d]{1,3}).([d]{1,3}).([d]{1,3})$/", $_SERVER['HTTP_X_FORWARDED_FOR'] ) ? $_SERVER['HTTP_X_FORWARDED_FOR'] : $_SERVER['REMOTE_ADDR'] );
}
</code></pre>
