How do I check OS with a preprocessor directive?

c operating-system c-preprocessor conditional-compilation

perimosocordiae · Sep 27, 2008 · Viewed 149.7k times · Source

I need my code to do different things based on the operating system on which it gets compiled. I'm looking for something like this:

#ifdef OSisWindows
// do Windows-specific stuff
#else
// do Unix-specific stuff
#endif

Is there a way to do this? Is there a better way to do the same thing?

Answer

The Predefined Macros for OS site has a very complete list of checks. Here are a few of them, with links to where they're found:

_WIN32 Both 32 bit and 64 bit
_WIN64 64 bit only

See this related question on some of the pitfalls of using this check.

unix
__unix
__unix__

__APPLE__
__MACH__

Both are defined; checking for either should work.

__linux__
linux Obsolete (not POSIX compliant)
__linux Obsolete (not POSIX compliant)

__FreeBSD__

__ANDROID__