$this->uri->segment（3）在 codeigniter 分页中的用途是什么

听到是我的代码

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);

}

在 codeigniter 中有什么用处$this->uri->segment(3)

我输入它按预期工作，但当我输入时，它停止工作$this->uri->segment(3);$this->uri->segment(4);