[php] what is the use of $this->uri->segment(3) in codeigniter pagination

hear is my code

public function viewdeletedrecords()
{   

    if($this->session->userdata('applicant_firstname') == '')
    {
        redirect('papplicant/login') ;
    }
    $profile = $this->m_applicant->showdeletedrecods('','');                                                         
    $total_rows = count($profile) ;
    $config['base_url'] =  base_url().'index.php/papplicant/viewdeletedrecords/' ;
    $config['per_page'] = '10' ;
    $config['full_tag_open'] = '<div>' ;

    $config['full_tag_close'] = '</div>' ;

    $config['first_link'] = 'First' ;

    $config['last_link'] = 'Last' ;

    $config['use_page_numbers'] = TRUE ;

    $config['prev_link'] = '&lt;' ;

    $config['uri_segment'] = 3 ;

    $config['num_links'] = 10 ;         

    $config['cur_tag_open'] = '<b>' ;

    $config['cur_tag_close'] = '</b>' ;

    $config['total_rows'] = $total_rows ;       

    $invoicepaginate = $this->m_applicant->showdeletedrecods( $config['per_page'], $this->uri->segment(3)) ;    

    $this->pagination->initialize($config);     

    $data4 = array(                             

    'data' => $invoicepaginate                                                                                       

    ) ;

    $this->load->view('applicant', $data4);

}

what is the use of $this->uri->segment(3) in codeigniter

whan I enter $this->uri->segment(3); it works as expected but when I enter $this->uri->segment(4); it stops working

Let's say you have a url like this http://www.example.com/controller/action/arg1/arg2

If you want to know what are the arguments that are being passed in this url

$param_offset=0;
$params = array_slice($this->uri->rsegment_array(), $param_offset);
var_dump($params);

Output will be:

array (size=2)
  0 => string 'arg1'
  1 => string 'arg2'

By default the function returns FALSE (boolean) if the segment does not exist. There is an optional second parameter that permits you to set your own default value if the segment is missing. For example, this would tell the function to return the number zero in the event of failure: $product_id = $this->uri->segment(3, 0);

It helps avoid having to write code like this:

[if ($this->uri->segment(3) === FALSE)
{
    $product_id = 0;
}
else
{
    $product_id = $this->uri->segment(3);
}]

This provides you to retrieve information from your URI strings

$this->uri->segment(n); // n=1 for controller, n=2 for method, etc

Consider this example:

http://example.com/index.php/controller/action/1stsegment/2ndsegment

it will return

$this->uri->segment(1); // controller
$this->uri->segment(2); // action
$this->uri->segment(3); // 1stsegment
$this->uri->segment(4); // 2ndsegment

In your code $this->uri->segment(3) refers to the pagination offset which you use in your query. According to your $config['base_url'] = base_url().'index.php/papplicant/viewdeletedrecords/' ;, $this->uri->segment(3) i.e segment 3 refers to the offset. The first segment is the controller, second is the method, there after comes the parameters sent to the controllers as segments.

CodeIgniter User Guide says:

$this->uri->segment(n)

Permits you to retrieve a specific segment. Where n is the segment number you wish to retrieve. Segments are numbered from left to right. For example, if your full URL is this: http://example.com/index.php/news/local/metro/crime_is_up

The segment numbers would be this:

1. news
2. local
3. metro
4. crime_is_up

So segment refers to your url structure segment. By the above example, $this->uri->segment(3) would be 'metro', while $this->uri->segment(4) would be 'crime_is_up'.