C++ FAQ Celebrating Twenty-One Years of the C++ FAQ!!!
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Section 40:
[40.4] Is there a C++-mode for GNU emacs? If so, where can I get it?

Yes, there is a C++-mode for GNU emacs.

The latest and greatest version of C++-mode (and C-mode) is implemented in the file cc-mode.el. It is an extension of Detlef and Clamen's version. A version is included with emacs. Newer version are available from the elisp archives.