Emacs : eldoc mode and c-eldoc mode

eldoc mode as the name suggests provides documentation for Elisp files. This is a very useful and cool mode and shows the function signature in the mode-line when your cursor is on a particular function.  It also provides info on the variables. Check out the screen-shots below.

To start eldoc mode, add the following to your .emacs file

;;Turn on documentation in elisp mode
(add-hook 'emacs-lisp-mode-hook
          '(lambda ()
	     (turn-on-eldoc-mode)))

c-eldoc mode is eldoc mode for c. It displays the arguments of C functions while one is programming.

To add c-eldoc mode, get the latest c-eldoc.el, copy it in your load-path and then add then following to your .emacs file.

(add-hook 'c-mode-hook 'c-turn-on-eldoc-mode)