Code formatter / beautifier for C on Linux for Emacs user

Question

I'm a Linux user looking for a code beautifier which will take files containing C code and format them to specification. Specifically, I'm looking to:

• Change all indentations to be 8 spaces
• Format blocks of code consistently
• Add line breaks consistently

It would be nice if it had both defaults and the ability to customize. I prefer free / open source solutions when available. Any suggestions?

UPDATE: I should also note than I'm an emacs user, and so this may be an emacs specific question. I've updated the tags to reflect this.

Answer 1

"indent" and "cb" come with most distros I've had...

Answer 2

Did you look at GNU indent ?

Answer 3

Astyle is worth a look.

Answer 4

emacs? That's probably more than you're looking for, but it WILL do it...

Answer 5

If you want the (external) indentation engine to play well with Emacs, you'll want to be sure to set up your cc-mode indentation to match. There are many built-in styles you can use. And if none of them meet your needs, you can customize the settings (of particular use is the interactive customization).

Another, inferior, solution would be to set up your before-save-hook to call the indentation scheme. Something like the following:

(add-hook 'c-mode-common-hook 
     (labmda ()) (add-hook (make-local-variable 'before-save-hook) 
                           'indent-it-all))
(defun indent-it-all ()
  "indent the buffer using indent"
  (shell-command-on-region (point-min) (point-max) "indent" t t))

Answer 6

This is what I use personally, and I think it satisfies all of your indentation needs, you can try it by adding the code to your .emacs file. This function takes care of proper indentation when I'm writing code:

(defun linux-c-indent ()
  "adjusted defaults for C/C++ mode use"
  (interactive)
  (setq tab-width 8)
  (setq indent-tabs-mode nil) ;;force spaces, to work with dumber editors
  (setq c-basic-offset 8)
  (setq c-set-style "K&R"))

(add-hook 'c-mode-common-hook 'linux-c-indent)

And if I wish to re-indent files written by other people, I use the following:

(defun iwb ()
  "indent whole buffer"
  (interactive)
  (delete-trailing-whitespace)
  (indent-region (point-min) (point-max) nil)
  (untabify (point-min) (point-max)))

The iwb function runs every time I open a "programming" file in emacs. That way, I always see well-indented code. I can put up that bit of code too I you want it.