php use ip as id code example

Example 1: php get user ip

$ip = $_SERVER['REMOTE_ADDR'];

Example 2: php get user ip address

#to best handle proxies use this:
if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
    $ip = $_SERVER['HTTP_CLIENT_IP'];
} elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
} else {
    $ip = $_SERVER['REMOTE_ADDR'];
}