CodeIgniter Multi-module configuration issues

I want to use CodeIgniter to develop a project, the front and rear stations are independent of the two modules;
Built two entry files: home.php and admin.php, respectively, corresponding to the foreground and backstage;
Application also built two application directories: admin and Home
But when I visited localhost/admin.php, I reported 404 mistakes, I do not know what the reason is, ask you the great God

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I want to use CodeIgniter to develop a project, the front and rear stations are independent of the two modules;
Built two entry files: home.php and admin.php, respectively, corresponding to the foreground and backstage;
Application also built two application directories: admin and Home
But when I visited localhost/admin.php, I reported 404 mistakes, I do not know what the reason is, ask you the great God

modifying parameters in admin.php
$routing [' directory '] = ' admin '
Create an admin file inside the controllers
Look at config/routes.php.
$route [' default_controller '] = ' welcome ';
Create a welcome.php in Controllers/admin
You can have it.

This is my sub-directory, in index.php modified System_path and Application_folder

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