For example, not every compiler for the Win32 platform has implemented C99 integer and boolean types, so I have stdint.h and stdbool.h files. Fortunately, The Open Group maintains an online definition for stdint.h and stdbool.h so I don’t have to guess about what is supposed to go in there. C99 also defines some new keywords:
_Bool is used by stdbool.h, it may or may not have been defined by the compiler. What I needed was a macro defined by the compiler that tells me which compiler it is so I can avoid compiler warnings.
Digging up the compiler macros on the internet can be challenging. However, there is a nice project at SourceForge to track Pre-defined C/C++ Compiler Macros.
That makes things a whole lot easier!