If you changed your project file (not source) extension from .cpb to .cpp, then you are getting confused with our advice. .cpb is just a file that codeblocks uses to manage the project.
My advice (since extensions seem to be mangled), create a new C++ project, not C, in code blocks and copy over the source. The only problem that were having in the beginning is that you are trying to compile a C++ source file under a C project.
This post has been edited by jjl: 18 April 2013 - 02:21 PM