Can’t connect to MySQL from PHP script running on the PHP builtin server (localhost)

I am trying to connect to the MySQL service provided by XAMPP (screenshot) through a PHP script that runs on the builtin PHP server (I started the server through php -S localhost:4242 in the folder where I have the scripts). However, when I try to connect to the database, I receive this error:

Access denied for user ”@’localhost’ (using password: NO)

In my connection script, I have:

class DB
{
    private $host = 'localhost';
    private $user = 'root';
    private $pwd = '';
    private $dbname = 'mydb';

    public function create_connection() {
        $conn = new mysqli($host, $user, $pwd, $dbname);
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
          }

        return $conn;
    }
}

When I call create_connection() I receive the error above. The MySQLi extension is enabled in my PHP. What am I doing wrong?

PS: I don’t want to move everything to XAMPP’s htdocs, I would like to access MySQL from the scripts outside.

Update The problem was solved. The issue was confusion between instance/class variables, and now connection works. The correct statement is:

$conn = new mysqli($this->host, $this->user, $this->pwd, $this->dbname);