git clone https://github.com/fredericfrances/company-c-preprocessor.git in your .emacs
(add-to-list 'load-path "<path to company-c-preprocessor clone directory>")Add this in emacs load path.
melpa comming soon.
(require 'company-c-preprocessor)
(add-to-list 'company-backends 'company-c-preprocessor)