Fortunately, there exist at least two decent C compilers for Windows that I know of: GCC and ICC. GCC provides the same FOSS compiler available on every other platform, and also allows cross-compiling from FOSS platforms to Windows, which helps when producing cross-platform binaries (to avoid needing to have a Windows system around to build release binaries). ICC doesn't use a FOSS license, and it lags behind GCC, but it does provide a replacement backend for Visual C++, which can make it more usable in some environments. Either one provides much better support for C than the Visual C++ C compiler.