CodeIgniter链接到另一个页面/控制器

I am a beginner in CodeIgniter framework and I have problem with links. I found a couple of pages in which is explained how to link pages, but from some reason I have problem to link two pages. I did this:

<a href="<?php echo site_url('controller_proffesor') ?>">Insert Labwork</a>

and that should call controller_proffesor method :

function index(){
    $this->load->view('proffesor_view_insert_labwork');
}

i try also this:

<a href="<?php echo site_url('controller_proffesor/index') ?>">Insert Labwork</a>

but when i click on that link this is what i get:

A PHP Error was encountered
Severity: Notice
Message: Undefined property: Controller_proffesor::$load
Filename: controllers/controller_proffesor.php
Line Number: 7
Backtrace:

i have also include this line in my autoload file :

$autoload['helper'] = array('url','form');

What am I doing wrong?

Within the constructor have you added:

parent::__construct();

Try adding it inside __construct(). It invokes the constructor of inherited parent class CI_Controller.

Your code should look like this..

class Controller_proffesor extends CI_Controller {
    public function __construct()
    {
        parent::__construct();

        //followed by your helper, model load statements
    } 

NOTE: Refer this https://stackoverflow.com/a/21339891/5176188 for more details. This may be a duplicate question.

Try this:

In your config file you must set something like this:

$autoload['helper'] = array('url','form','html');

In the controller, you must forget to extend it and the name also must concide with the name of your class and it is also like the model extends it to CI_Model

Class Class_Name extends CI_Controller {

   public function __construct () {
      parent::__construct    
      // you can load here the session and models
   }
}

Hope it helps.