How do I check OS with a preprocessor directive?

Question

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         


        

Answer 1

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:

Windows

_WIN32   Both 32 bit and 64 bit
_WIN64   64 bit only

Unix (Linux, *BSD, Mac OS X)

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

unix
__unix
__unix__

Mac OS X

__APPLE__
__MACH__

Both are defined; checking for either should work.

Linux

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

FreeBSD

__FreeBSD__

Android

__ANDROID__