How should I call this function? PHP

Question

How should I call this function? I'm new to PHP. Here's my code... but I have an error

Notice: Undefined variable: ip in C:\xampp\htdocs\PHPTest\ip.php on line 19

    <?php
    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 $ip;
    }
    call_user_func('getRealIpAddr', '$ip');
    echo $ip;
    ?>

UPDATE

Strange reason, I'm using Windows 10, localhost, xampp and google Chrome this script doesn't provide me an ip address! That's why a corrected code was empty... Thought it was some kind of errors or something

Second UPDATE

If you're getting no ip like me, you may try this solution on httpd.conf

Answer 1

Error is very clear $ip is not defined:

Modified Code:

<?
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;
}

$ip = getRealIpAddr(); // your function
echo $ip;
?>

If you want to use $ip variable that you defined inside the function than note that scope of the $ip is limited into the function.

You can not call this variable outside the function. for this you need to store it in a variable as like above mentioned example ($ip = getRealIpAddr();).