call one controller to another controller

I think you need HMVC.

https://bitbucket.org/wiredesignz/codeig...downloads/

Modular Extensions makes the CodeIgniter PHP framework modular. Modules are groups of independent components, typically model, controller and view, arranged in an application modules sub-directory that can be dropped into other CodeIgniter applications.

HMVC stands for Hierarchical Model View Controller.

Module Controllers can be used as normal Controllers or HMVC Controllers and they can be used as widgets to help you build view partials.