通过google找到了一些随机博客.有趣的代码实际上是在注释中，而不是博客所提到的.

Some random blog found via google . The interesting code is actually in the comment rather than what the blogger has mentioned.

function getIpAddress() 
{
    return (empty($_SERVER['HTTP_CLIENT_IP'])?(empty($_SERVER['HTTP_X_FORWARDED_FOR'])?
    $_SERVER['REMOTE_ADDR']:$_SERVER['HTTP_X_FORWARDED_FOR']):$_SERVER['HTTP_CLIENT_IP']);
}




function getRealIpAddr()
{
    if (!empty($_SERVER['HTTP_CLIENT_IP']))   //check ip from share internet
    {
      $ip=$_SERVER['HTTP_CLIENT_IP'];
    }
    elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))   //to check ip is pass from proxy
    {
      $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
    }
    else
    {
      $ip=$_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}