PHP IP请求给出错误

Hey, PHP newbie here when I try to run this to get an IP it give me

Fatal error: Cannot access self:: when no class scope is active in /home/content/56/6442856/html/unlocking/Untitled-4.php on line 14

What am I doing wrong here?

Also, please remember: PHP newbie here, so explain as much as possible.

Thanks

<?php 
function get_ip_address()
{
    foreach (array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR') as $key)
    {
        if (array_key_exists($key, $_SERVER) === true)
        {
            foreach (explode(',', $_SERVER[$key]) as $ip)
            {
                $ip = trim($ip); // just to be safe

                if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) !== false)
                {
                    self::$ip = $ip; return $ip;
                }
            }
        }
    }
}

get_ip_address();
echo $ip;
?>

function get_ip_address()
{
    foreach (array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR') as $key)
    {
        if (array_key_exists($key, $_SERVER) === true)
        {
            foreach (explode(',', $_SERVER[$key]) as $ip)
            {
                $ip = trim($ip); // just to be safe

                if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) !== false)
                {
                    return $ip;
                }
            }
        }
    }
}

echo get_ip_address();

And i don't know if you really need such a function to get the IP of the client.

echo $_SERVER['REMOTE_ADDR'];

could be sufficient imo

You're getting the error because of this line :

self::$ip = $ip; return $ip;

You use self when you're inside a class and referring to one of its static members :

class Foo
{
    public static $my_static = 'foo';

    public function staticValue() {
        return self::$my_static; //It's correctly used here
    }
} 

as for the solution specific to your problem yes123 has already covered it.