get IP address from behind proxy/cloudflare - PHP

<?php

// author: vvn
// see a working example of the script at http://bit.ly/QUxT4N

$arr = array('HTTP_CLIENT_IP', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_CF_CONNECTING_IP', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR');

foreach ($arr as $i=>$key){

    echo $key;
    echo " = <b>";
    echo $_SERVER[$key];
    echo "</b><br /><br />";

    if (!empty($_SERVER[$key])){
        $ip = $_SERVER[$key];

    }

}

echo "<p><hr /></p>";
echo "your most likely IP address is:<br /><br />";
echo "<b style='color:#900; font-size:20px;'>".$ip."</b> which resolves to <b style='color:#900; font-size:20px;'>".gethostbyaddr($ip);
echo "</b>";

?>