case 'check':
$index->checkLogin();
break;
case 'delete':
break;
case 'edit':
if ($_SESSION['user_type'] == 1) {
$index->showEditScreen();
}
break;
case 'logout':
$index->logout();
break;
case 'manage':
if ($_SESSION['user_type'] == 1) {
$index->showManagement();
}
break;
case 'register':
$index->showRegister('show');
break;
case 'checkr':
$index->register();
break;
case 'search':
$index->search('autor');
break;
case 'searchb':
$index->search('book');
break;
case 'submit':