<?php
    class userAuth {
        public $username;
        private $password;
        private $_resultCode;

        public function _construct($username,$password) {
            $this->username = $username;
            $this->password = $password;
            $this->_resultCode = -1;
        }

        public function getResultCode() {
            return $this->_resultCode;
        }

        public function authenticateUser() {
            if($this->username == "billy") {
                $this->_resultCode = 1;
                if ($this->password == "test") $this->_resultCode = 2;
            } else $this->_resultCode = -1;
        }

    }
?>

<?php
    $user_auth = new userAuth("test", "123");
    echo $user_auth->username;
?>