I\'m writing ANSI-compatible C code, and hence I can\'t use the line (//) comment. I\'m using Xcode. In Sublime Text and Eclipse, and I think most other IDEs, t
There is now an Xcode plugin that allows this: CComment.
The easiest way to install this is to use the amazing Alcatraz plugin manager for Xcode.
EDIT Apple has sadly (and wrongly, IMHO) retired the old plugin model with Xcode 8. The new plugin system is quite limited, but should allow development of a plugin like this again. For anyone interested in doing this, watch WWDC 2016 session 414. Also, please file radars for API for plugins you'd like to write or see.