Variable in php class which can be used in all its functions - php

Question

I want to declare a variable in a php class which can be used in all its functions. I am using the codeigniter framework & to have to pass data like base_url etc in each of the functions. Also I need all of such data in a single variable. For example $data['base_url']=base_url(), $data['title']="My_Site_title" etc & then send only a single variable $data (this is a common thing in codeigniter).
As per this question, I modified my code to:
class Search extends CI_Controller {
function Search() {
parent::__construct();
$this->load->model('student_model');
$this->load->helper('form');
$this->load->helper('url');
$this->output->enable_profiler(TRUE);
$this->data['base_url']=base_url(); //gives an error here
}
function index() {
$this->load->view('search_view', $this->data);
}
}
But still it gives an error at the marked place saying Undefined variable: data and Fatal error: Cannot access empty property in ..\search.php on line 16.

Answer 1

Here you go:
class Search extends CI_Controller {
protected $data = array();
function Search() {
parent::__construct();
$this->load->model('student_model');
$this->load->helper('form');
$this->load->helper('url');
$this->output->enable_profiler(TRUE);
$this->data['base_url']=base_url();
}
function index() {
$this->load->view('search_view', $this->data);
}
}
More about class properties in php: http://php.net/manual/en/language.oop5.properties.php