public function loginAction()
    {
        // action body
        $auth_adapter=$this->getAuthAdapter();
        echo gettype($auth_adapter);
        $username='JmcC';
        $password='123';
        $auth_adapter->setIdentity($username)
                     ->setCredential($password);
        $auth=Zend_Auth::getInstance();
        $out=$auth->authenticate($auth_adapter);
            if($out->isValid()){
                echo ' pass' ;
                }else{
                    echo 'Not pass';
                    }


        $this->view->loginForm=$loginForm;

    }
     private function getAuthAdapter() {
        $authAdapter=new Zend_Auth_Adapter_DbTable(Zend_Db_Table_Abstract::getDefaultAdapter());
        $authAdapter->setTableName('users')
                    ->setIdentityColumn('username')
                    ->setCredentialColumn('password')
                    ->setCredentialTreatment('MD5(?)');

     }
-------------------
Output:

NULL
Fatal error: Call to a member function setIdentity() on a non-object in C:\xampp\htdocs\Eco-Cars\application\controllers\AccountsController.php on line 53