Controller Suffix

Can someone help me, please;

I want to set every controller name  with '_controller' at end file name and controller class name

example:

PHP Code:

/**
* Filename: application/Welcome.php
*/

Class Wecome extends CI_Controller {} 


replace:

PHP Code:

/**
* Filename: application/Welcome_controller.php
*/

Class Welcome_controller extends CI_Controller {} 


but in url still like this:
http://localhost:8000/welcome

without _controller