global variable in controllers

[eluser]brian88[/eluser]
For my controller, I was wondering how to use the same variable for more than 1 function.

Code:

class Main extends CI_Controller {
  function __construct() {
    parent::__construct();
    $v = "23";
  }

  function index() {
    echo $v; // doesnt work, undefined var
  }
}

[eluser]Learn CodeIgniter[/eluser]

Code:

class Main extends CI_Controller {

  public $v;

  function __construct()
  {
    parent::__construct();

    $this->v = "23";
  }

  function index()
  {
    echo $this->v; // doesnt work, undefined var
  }
}