mysqli_real_escape_string returns empty inside function

Question

I made a function which has to filter the data passed into a $_GET variable. It recently worked, but I began working with mysqli and now it's not anymore. Echoing my $data everytime it went through a PHP function gave the result that the mysqli_real_escape_string causing the variable $data to return empty . But what am I doing wrong here.

My function which should filter the $_GET variables, but the mysqli_real_escape_string returns an empty variable..

    function filter($data) {
            global $link;
            $data = trim(htmlentities(strip_tags($data)));
            if (get_magic_quotes_gpc())
                $data = stripslashes($data);
            $data = mysqli_real_escape_string($link, $data);    
            return $data;
        }

A loop in order to run all $_GET variables trough the filter.

foreach($_GET as $key => $value) {
    $get[$key] = filter($value);
}   

The connection with the database (the connection does work): ( $link )

$link=mysqli_connect(DB_HOST,DB_USER,DB_PASS,DB_NAME); 

Answer 1

Modify your function to include $link and pass it by reference if you like:

function filter($data, &$link) {
    $data = trim(htmlentities(strip_tags($data)));
    if (get_magic_quotes_gpc())
        $data = stripslashes($data);
    $data = mysqli_real_escape_string($link, $data);    
    return $data;
}