It doesn't find my class even if it exists - codeigniter-3

Question

This is the error:
Fatal error: Class 'Admin_Controller' not found in C:\xampp\htdocs\ci-blog-master\application\modules\admin\controllers\Settings.php on line 4
A PHP Error was encountered
Severity: Error
Message: Class 'Admin_Controller' not found
Filename: controllers/Settings.php
Line Number: 4
Backtrace:
And here is my code for :
Admin_controller.php
<?php defined('BASEPATH') OR exit('No direct script access allowed');
class Admin_Controller extends MY_Controller {
function __construct()
{
parent::__construct();
}
}
And here is my Settings.php
class Settings extends Admin_Controller {
public function __construct(){
parent::__construct();
$this->allow_group_access(array('admin'));
$this->load->model('Category');
$this->data['parent_menu'] = 'post';
}
public function index(){
$this->session->set_flashdata('message',message_box('Setting is the coming soon feature!','danger'));
redirect('admin/posts/index');
$config['base_url'] = site_url('admin/categories/index/');
$config['total_rows'] = count($this->Category->find());
$config['per_page'] = 10;
$config["uri_segment"] = 4;
$this->data['categories'] = $this->Category->find($config['per_page'], $this->uri->segment(4));
$this->data['pagination'] = $this->bootstrap_pagination($config);
$this->render('admin/categories/index');
}
public function add(){
$this->form_validation->set_rules('name', 'name', 'required|is_unique[categories.name]');
$this->form_validation->set_rules('status', 'status', 'required');
if($this->form_validation->run() == true){
$category = array(
'name' => $this->input->post('name'),
'status' => $this->input->post('status')
);
$this->Category->create($category);
$this->session->set_flashdata('message',message_box('Category has been saved','success'));
redirect('admin/categories/index');
}
$this->render('admin/categories/add');
}
public function edit($id = null){
if($id == null){
$id = $this->input->post('id');
}
$this->form_validation->set_rules('name', 'name', 'required');
$this->form_validation->set_rules('status', 'status', 'required');
if($this->form_validation->run() == true){
$category = array(
'name' => $this->input->post('name'),
'status' => $this->input->post('status')
);
$this->Category->update($category, $id);
$this->session->set_flashdata('message',message_box('Category has been saved','success'));
redirect('admin/categories/index');
}
$this->data['category'] = $this->Category->find_by_id($id);
$this->render('admin/categories/edit');
}
public function delete($id = null){
if(!empty($id)){
$this->Category->delete($id);
$this->session->set_flashdata('message',message_box('Category has been deleted','success'));
redirect('admin/categories/index');
}else{
$this->session->set_flashdata('message',message_box('Invalid id','danger'));
redirect('admin/categories/index');
}
}
public function update_multiple(){
#test commit
#test commit di branch sendiri
}
}

Answer 1

You can put more classes in MY_Controller.php file:
<?php defined('BASEPATH') OR exit('No direct script access allowed');
class MY_Controller extends CI_Controller
{
public function __construct()
{
parent::__construct();
}
public function some_mycontr_method()
{
// appropriate code here
}
}
class Admin_Controller extends MY_Controller
{
public function __construct()
{
parent::__construct();
}
public function some_admin_method()
{
// appropriate code here
}
}