[c++] How to identify platform/compiler from preprocessor macros?

I'm writing a cross-platform code, which should compile at linux, windows, Mac OS. On windows, I must support visual studio and mingw.

There are some pieces of platform-specific code, which I should place in #ifdef .. #endif environment. For example, here I placed win32 specific code:

#ifdef WIN32
#include <windows.h>
#endif

But how do I recognize linux and mac OS? What are defines names (or etc.) I should use?

If you're writing C++, I can't recommend using the Boost libraries strongly enough.

The latest version (1.55) includes a new Predef library which covers exactly what you're looking for, along with dozens of other platform and architecture recognition macros.

#include <boost/predef.h>

// ...

#if BOOST_OS_WINDOWS

#elif BOOST_OS_LINUX

#elif BOOST_OS_MACOS

#endif

See: http://predef.sourceforge.net/index.php

This project provides a reasonably comprehensive listing of pre-defined #defines for many operating systems, compilers, language and platform standards, and standard libraries.

Here's what I use:

#ifdef _WIN32 // note the underscore: without it, it's not msdn official!
    // Windows (x64 and x86)
#elif __unix__ // all unices, not all compilers
    // Unix
#elif __linux__
    // linux
#elif __APPLE__
    // Mac OS, not sure if this is covered by __posix__ and/or __unix__ though...
#endif

EDIT: Although the above might work for the basics, remember to verify what macro you want to check for by looking at the Boost.Predef reference pages. Or just use Boost.Predef directly.