Getting emacs M-; to produce // style comments

How do I change the style of comments for M-; (comment-dwim) when using c-mode?

I would like it to use 开发者_如何学JAVAcomments preceeded by // instead of /* */ nesting.

Version:

GNU Emacs 23.2.1 (x86_64-pc-linux-gnu, GTK+ Version 2.20.1) of 2010-12-11 on brahms, modified by Debian

The relevant vars are comment-start and comment-end so you can use this:

(add-hook 'c-mode-hook (lambda () (setq comment-start "//"
                                        comment-end   "")))

From http://www.cs.cmu.edu/cgi-bin/info2www?(emacs)C%20Mode:

C++ mode is like C mode, except that it understands C++ comment syntax and certain other differences between C and C++. It also has a command `M-x fill-c++-comment', which fills a paragraph made of C++ comment lines.

So you can just add this line to your .emacs:

(add-to-list 'auto-mode-alist '("\\.[ch]\\'" . c++-mode))