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

On MinGW, the _WIN32 define check isn't working. Here's a solution:

#if defined(_WIN32) || defined(__CYGWIN__)
    // Windows (x86 or x64)
    // ...
#elif defined(__linux__)
    // Linux
    // ...
#elif defined(__APPLE__) && defined(__MACH__)
    // Mac OS
    // ...
#elif defined(unix) || defined(__unix__) || defined(__unix)
    // Unix like OS
    // ...
#else
    #error Unknown environment!
#endif

For more information please look: https://sourceforge.net/p/predef/wiki/OperatingSystems/

Answer 2

Use #define OSsymbol and #ifdef OSsymbol where OSsymbol is a #define'able symbol identifying your target OS.

Typically you would include a central header file defining the selected OS symbol and use OS-specific include and library directories to compile and build.

You did not specify your development environment, but I'm pretty sure your compiler provides global defines for common platforms and OSes.

See also http://en.wikibooks.org/wiki/C_Programming/Preprocessor

Answer 3

Microsoft C/C++ compiler (MSVC) Predefined Macros can be found here

I think you are looking for:

• _WIN32 - Defined as 1 when the compilation target is 32-bit ARM, 64-bit ARM, x86, or x64. Otherwise, undefined
• _WIN64 - Defined as 1 when the compilation target is 64-bit ARM or x64. Otherwise, undefined.

gcc compiler PreDefined MAcros can be found here

I think you are looking for:

• __GNUC__
• __GNUC_MINOR__
• __GNUC_PATCHLEVEL__

Do a google for your appropriate compilers pre-defined.

Answer 4

Sorry for the external reference, but I think it is suited to your question:

C/C++ tip: How to detect the operating system type using compiler predefined macros

Answer 5

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__

Answer 6

show GCC defines on Windows:

gcc -dM -E - <NUL:

on Linux:

gcc -dM -E - </dev/null

Predefined macros in MinGW:

WIN32 _WIN32 __WIN32 __WIN32__ __MINGW32__ WINNT __WINNT __WINNT__ _X86_ i386 __i386

on UNIXes:

unix __unix__ __unix