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I often see __WIN32, WIN32 or __WIN32__. I assume that this depends on the used preprocessor (either one from visual studio, or gcc etc).
Do I now have to check first for os and then for the used compiler? We are using here G++ 4.4.x, Visual Studio 2008 and Xcode (which I assume is a gcc again) and ATM we are using just __WIN32__, __APPLE__ and __LINUX__.
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The symbol _WIN32 is defined by the compiler to indicate that this is a (32bit) Windows compilation. Unfortunately, for historical reasons, it is also defined for 64-bit compilation. The symbol _WIN64 is defined by the compiler to indicate that this is a 64-bit Windows compilation.
_MSC_VER Defined as an integer literal that encodes the major and minor number elements of the compiler's version number. The major number is the first element of the period-delimited version number and the minor number is the second element. For example, if the version number of the Microsoft C/C++ compiler is 17.00.
This article answers your question:
The article is quite long, and includes tables that are hard to reproduce, but here's the essence:
You can detect Unix-style OS with:
#if !defined(_WIN32) && (defined(__unix__) || defined(__unix) || (defined(__APPLE__) && defined(__MACH__))) /* UNIX-style OS. ------------------------------------------- */ #endif Once you know it's Unix, you can find if it's POSIX and the POSIX version with:
#include <unistd.h> #if defined(_POSIX_VERSION) /* POSIX compliant */ #endif You can check for BSD-derived systems with:
#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__)) #include <sys/param.h> #if defined(BSD) /* BSD (DragonFly BSD, FreeBSD, OpenBSD, NetBSD). ----------- */ #endif #endif and Linux with:
#if defined(__linux__) /* Linux */ #endif and Apple's operating systems with
#if defined(__APPLE__) && defined(__MACH__) /* Apple OSX and iOS (Darwin) */ #include <TargetConditionals.h> #if TARGET_IPHONE_SIMULATOR == 1 /* iOS in Xcode simulator */ #elif TARGET_OS_IPHONE == 1 /* iOS on iPhone, iPad, etc. */ #elif TARGET_OS_MAC == 1 /* OS X */ #endif #endif Windows with Cygwin
#if defined(__CYGWIN__) && !defined(_WIN32) /* Cygwin POSIX under Microsoft Windows. */ #endif And non-POSIX Windows with:
#if defined(_WIN64) /* Microsoft Windows (64-bit) */ #elif defined(_WIN32) /* Microsoft Windows (32-bit) */ #endif The full article lists the following symbols, and shows which systems define them and when: _AIX, __APPLE__, __CYGWIN32__, __CYGWIN__, __DragonFly__, __FreeBSD__, __gnu_linux, hpux, __hpux, linux, __linux, __linux__, __MACH__, __MINGW32__, __MINGW64__, __NetBSD__, __OpenBSD__, _POSIX_IPV6, _POSIX_MAPPED_FILES, _POSIX_SEMAPHORES, _POSIX_THREADS, _POSIX_VERSION, sun, __sun, __SunOS, __sun__, __SVR4, __svr4__, TARGET_IPHONE_SIMULATOR, TARGET_OS_EMBEDDED, TARGET_OS_IPHONE, TARGET_OS_MAC, UNIX, unix, __unix, __unix__, WIN32, _WIN32, __WIN32, __WIN32__, WIN64, _WIN64, __WIN64, __WIN64__, WINNT, __WINNT, __WINNT__.
A related article (archive.org link) covers detecting compilers and compiler versions. It lists the following symbols: __clang__, __GNUC__, __GNUG__, __HP_aCC, __HP_cc, __IBMCPP__, __IBMC__, __ICC, __INTEL_COMPILER, _MSC_VER, __PGI, __SUNPRO_C, __SUNPRO_CC for detecting compilers, and __clang_major__, __clang_minor__, __clang_patchlevel__, __clang_version__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__, __GNUC__, __GNUG__, __HP_aCC, __HP_cc, __IBMCPP__, __IBMC__, __ICC, __INTEL_COMPILER, __INTEL_COMPILER_BUILD_DATE, _MSC_BUILD, _MSC_FULL_VER, _MSC_VER, __PGIC_MINOR__, __PGIC_PATCHLEVEL__, __PGIC__, __SUNPRO_C, __SUNPRO_CC, __VERSION__, __xlC_ver__, __xlC__, __xlc__ for detecting compiler versions.
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