How to get value from URL in Codeigniter?

Get value from URL in Codeigniter

Paste in Controller

$user_id = $this->uri->segment(2);

//$user_id = $this->uri->segment(position_after_index.php);

Paste in View

<?php echo base_url('index.php/update/'.$row['ID']); ?>

//http://localhost/codelearning/index.php/update/26

Paste in Routes

$route['update/(:any)'] = 'welcome/update_user';

$route['page_name/(:any)'] = 'conroller_name/controller_function';