In which files routes are defined in Codeigniter?
Codeigniter | routes
Routing rules are defined in your application/config/routes.php file.
In it, you'll see an array called $route that permits you to specify your own routing criteria. Routes can either be specified using wildcards or Regular Expressions.
The default code present in the application/config/routes.php file
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
$route['default_controller'] = 'welcome';
$route['404_override'] = '';
$route['translate_uri_dashes'] = FALSE;
?>