@koder: Qt SDK does not install g++ for you (except the Windows one which comes with MingW) on other platforms you need to install g++ and make.

And on-topic, g++ (or mingw) got to compile C code not only C++, off course if your code is standard C. (most C code is also C++)

So i suggest you try to create a project, you can start with a "Empty project" and add your files (.c and .h) to that project and see if you will have any issues.
After you start, if you run into troubles you can post again, and depending on what you are trying to achieve we may be able to give you better advices.

NOTE: C++ compilers have the C header files from C standard library, but there are without .h extension and have 'c' prefix: like in place of "#include <stdio.h>" you will write "#include <cstdio>" and so on...