I have this function on my function.php
function getPassword($username, $conn){
    if ($stmt2 = mysqli_prepare($conn, "SELECT data FROM xf_user_authenticate WHERE username = ?")){
        mysqli_stmt_bind_param($stmt2, "s", $username);
        mysqli_stmt_execute($stmt2);
        mysqli_stmt_bind_result($stmt2, $password);
        mysqli_stmt_fetch($stmt2);
        mysqli_stmt_close($stmt2);
        $password = substr($password, 22, -3);
        return $password;
    }
}
And I have a check.php file that's give me this error
Notice: Undefined variable: username
Notice: Undefined variable: conn
I go with global $username but the selection from database not work. Why its give me this error?
 
     
    