Baris Yuksel has a nice set of videos (Part 1, Part 2) that show you how to configure Emacs to be a reasonable IDE for C and C++. In the first video Yuksel talks about auto-complete, auto-complete-c-headers, and yasnippet. Adding these three packages allow a programmer to autocomplete many of the common C/C++ objects.
The second video discusses iedit, flymake-google-cpplint, google-c-style, and flymake-cursor-mode. Together with the packages from the first video, they make a very nice C/C++ environment. The flymake-google-cpplint and google-c-style packages help enforce Google coding standards. You may or may not subscribe to Google’s standards but there are also generic C++ checkers as well as checkers for many other languages. The flymake-cursor-mode puts a message in the minibuffer telling you what error the other flymake packages are complaining about for the line at the cursor.
Finally, iedit is sort of like Magnor Sveen’s multiple cursors. If you’re already using multiple cursors, you probably don’t need it.
Together the two videos are less than 15 minutes so it’s easy to fit them into your schedule. If you’re hacking C or C++ in Emacs, you should give them a look.