I’ve talked about eldoc in the past, a minor mode that displays arguments to functions in the echo area. Eldoc is mainly used for lisp and scheme files, although it also works with Python, but something fewer people realize is that there is a mode that turns eldoc on for C files.
Unfortunately, this package does not come built in to GNU Emacs. You can obtain it here and put it in your load path. It doesn’t work with C++ files; only straight C files can take advantage of it. This is better than nothing, anyway. Enabling it is quite simple: Add c-eldoc.el to your load path and add the following to your initialization file:
(require 'c-eldoc) (add-hook 'c-mode-hook 'c-turn-on-eldoc-mode)