<?php
class Database{

  private static $INSTANCE = null;
  private $mysqli,
          $HOST = "localhost",
          $USER = "root",
          $PASS = "gunawan02",
          $DBNAME = "loginOOP";

          public function  __construct(){
            $this->mysqli = new mysqli($this->HOST , $this->USER , $this->PASS , $this->DBNAME);
            if (mysqli_connect_error()) {
              die("error cant connect db");
            }
          }

          public static function getInstance(){
            if (!isset ( self::$INSTANCE )) {
              self::$INSTANCE = new Database();
            }
            else{
              return self::$INSTANCE;
            }
          }
}
//pemanggilan fungsi db
// Database::getInstance();
// atau
//
$db = Database::getInstance();
var_dump($db);




 ?>