A free C, C++ and Fortran IDE built to meet the most demanding needs of its users

Code::Blocks
Free
Offline
http://www.codeblocks.org/

Code::Blocks is a free C, C++ and Fortran IDE built to meet the most demanding needs of its users. It is designed to be very extensible and fully configurable.
Finally, an IDE with all the features you need, having a consistent look, feel and operation across platforms.