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?
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
__CYGWIN__
Unix (Linux, *BSD, but not Mac OS X)
See this related question on some of the pitfalls of using this check.
unix
__unix
__unix__
Mac OS X
__APPLE__ Also used for classic
__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__
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
Based on nadeausoftware and Lambda Fairy's answer.
#include <stdio.h>
/**
* Determination a platform of an operation system
* Fully supported supported only GNU GCC/G++, partially on Clang/LLVM
*/
#if defined(_WIN32)
#define PLATFORM_NAME "windows" // Windows
#elif defined(_WIN64)
#define PLATFORM_NAME "windows" // Windows
#elif defined(__CYGWIN__) && !defined(_WIN32)
#define PLATFORM_NAME "windows" // Windows (Cygwin POSIX under Microsoft Window)
#elif defined(__ANDROID__)
#define PLATFORM_NAME "android" // Android (implies Linux, so it must come first)
#elif defined(__linux__)
#define PLATFORM_NAME "linux" // Debian, Ubuntu, Gentoo, Fedora, openSUSE, RedHat, Centos and other
#elif defined(__unix__) || !defined(__APPLE__) && defined(__MACH__)
#include <sys/param.h>
#if defined(BSD)
#define PLATFORM_NAME "bsd" // FreeBSD, NetBSD, OpenBSD, DragonFly BSD
#endif
#elif defined(__hpux)
#define PLATFORM_NAME "hp-ux" // HP-UX
#elif defined(_AIX)
#define PLATFORM_NAME "aix" // IBM AIX
#elif defined(__APPLE__) && defined(__MACH__) // Apple OSX and iOS (Darwin)
#include <TargetConditionals.h>
#if TARGET_IPHONE_SIMULATOR == 1
#define PLATFORM_NAME "ios" // Apple iOS
#elif TARGET_OS_IPHONE == 1
#define PLATFORM_NAME "ios" // Apple iOS
#elif TARGET_OS_MAC == 1
#define PLATFORM_NAME "osx" // Apple OSX
#endif
#elif defined(__sun) && defined(__SVR4)
#define PLATFORM_NAME "solaris" // Oracle Solaris, Open Indiana
#else
#define PLATFORM_NAME NULL
#endif
// Return a name of platform, if determined, otherwise - an empty string
const char *get_platform_name() {
return (PLATFORM_NAME == NULL) ? "" : PLATFORM_NAME;
}
int main(int argc, char *argv[]) {
puts(get_platform_name());
return 0;
}
Tested with GCC and clang on:
Debian 8
Windows (MinGW)
Windows (Cygwin)
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.
In most cases it is better to check whether a given functionality is present or not. For example: if the function pipe() exists or not.
#ifdef _WIN32
// do something for windows like include <windows.h>
#elif defined __unix__
// do something for unix like include <unistd.h>
#elif defined __APPLE__
// do something for mac
#endif
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/
There is no standard macro that is set according to C standard. Some C compilers will set one on some platforms (e.g. Apple's patched GCC sets a macro to indicate that it is compiling on an Apple system and for the Darwin platform). Your platform and/or your C compiler might set something as well, but there is no general way.
Like hayalci said, it's best to have these macros set in your build process somehow. It is easy to define a macro with most compilers without modifying the code. You can simply pass -D MACRO to GCC, i.e.
gcc -D Windows
gcc -D UNIX
And in your code:
#if defined(Windows)
// do some cool Windows stuff
#elif defined(UNIX)
// do some cool Unix stuff
#else
# error Unsupported operating system
#endif
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
You can use Boost.Predef which contains various predefined macros for the target platform including the OS (BOOST_OS_*). Yes boost is often thought as a C++ library, but this one is a preprocessor header that works with C as well!
This library defines a set of compiler, architecture, operating system, library, and other version numbers from the information it can gather of C, C++, Objective C, and Objective C++ predefined macros or those defined in generally available headers. The idea for this library grew out of a proposal to extend the Boost Config library to provide more, and consistent, information than the feature definitions it supports. What follows is an edited version of that brief proposal.
For example
#include <boost/predef.h>
// or just include the necessary header
// #include <boost/predef/os.h>
#if BOOST_OS_WINDOWS
#elif BOOST_OS_ANDROID
#elif BOOST_OS_LINUX
#elif BOOST_OS_BSD
#elif BOOST_OS_AIX
#elif BOOST_OS_HAIKU
...
#endif
The full list can be found in BOOST_OS operating system macros
Demo on Godbolt
See also How to get platform IDs from boost?
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
Just to sum it all up, here are a bunch of helpful links.
GCC Common Predefined Macros
SourceForge predefined Operating Systems
MSDN Predefined Macros
The Much-Linked NaudeaSoftware Page
Wikipedia!!!
SourceForge's "Overview of pre-defined compiler macros for standards, compilers, operating systems, and hardware architectures."
FreeBSD's "Differentiating Operating Systems"
All kinds of predefined macros
libportable
I did not find Haiku definition here. To be complete, Haiku-os definition is simple __HAIKU__
Some compilers will generate #defines that can help you with this. Read the compiler documentation to determine what they are. MSVC defines one that's __WIN32__, GCC has some you can see with touch foo.h; gcc -dM foo.h
You can use pre-processor directives as warning or error to check at compile time you don't need to run this program at all just simply compile it .
#if defined(_WIN32) || defined(_WIN64) || defined(__WINDOWS__)
#error Windows_OS
#elif defined(__linux__)
#error Linux_OS
#elif defined(__APPLE__) && defined(__MACH__)
#error Mach_OS
#elif defined(unix) || defined(__unix__) || defined(__unix)
#error Unix_OS
#else
#error Unknown_OS
#endif
#include <stdio.h>
int main(void)
{
return 0;
}
I wrote an small library to get the operating system you are on, it can be installed using clib (The C package manager), so it is really simple to use it as a dependency for your projects.
Install
$ clib install abranhe/os.c
Usage
#include <stdio.h>
#include "os.h"
int main()
{
printf("%s\n", operating_system());
// macOS
return 0;
}
It returns a string (char*) with the name of the operating system you are using, for further information about this project check it out the documentation on Github.
Dear All I have a small Fortran program containing preprocessor macro. Below is a minimal example. On mac os x, it works well but when I compile it on windows 7 (64-bit) it always prints unknown operating system. I am using gfortran-4.8.0 (mingw32) on windows 7.
program foo
implicit integer(i-n), double precision (a-h,o-p),
+ character*8(x-z)
*
#ifdef _WIN64
zterm = 'wxt'
#elif _WIN32
zterm = 'wxt'
#elif __APPLE__
zterm = 'aqua'
#elif __linux
zterm = 'x11'
#elif __unix
zterm = 'x11'
#elif __posix
zterm = 'x11'
#else
print*, 'unknown operating system'
#endif
end program foo
Changing #ifdef _WIN64 to #if defined (_WIN64) did not help. Any suggestion will be appreciated.
This might be GFortran PR 42954. Since GFortran started using libcpp instead of running cpp in a separate process, many of these built-in macros are missing.
As a workaround, you can as part of your build process generate a file with these builtin macro definitions which you can then include. E.g. have a make target which runs
gcc -E -dM - < /dev/null > builtins.inc
Then your sources should depend on builtins.inc in the Makefile, and in the beginning of your source files you
#include "builtins.inc"
To handle platform specific code between Mac and Windows, WIN32 and APPLE are the terms to use, right?
So, thw code would look like this:
#ifdef _WIN32
// Windows code
#endif
#ifdef __APPLE__
// Mac code
#endif
What about Linux ?
How can i do that for all three? right
It's similar:
#ifdef __linux__
// Linux code
#endif
Since you are going to have either one of these three defined at a time, this should be ok for all three.
List of defines.
I am fairly new to C++. I am currently working on a group project and we want to make our classes compatible with both the lab computers (Windows) and my computer (Mac OS X).
Here is what we have been putting at the top of our files:
#ifdef TARGET_OS_X
# include <GLUT/glut.h>
# include <OpenGL/OpenGL.h>
#elif defined _WIN32 || defined _WIN64
# include <GL\glut.h>
#endif
I realize this question has been asked before but my searches have been giving me conflicting answers such as "_MAC", "TARGET_MAC_OS", "MACINTOSH", etc. What is the current and correct declaration to put in the #ifdef statement to make this compatible with Mac? Right now it is not working.
Thank you!
According to this answer:
#ifdef __APPLE__
#include "TargetConditionals.h"
#ifdef TARGET_OS_IPHONE
// iOS
#elif TARGET_IPHONE_SIMULATOR
// iOS Simulator
#elif TARGET_OS_MAC
// Other kinds of Mac OS
#else
// Unsupported platform
#endif
#endif
So in short:
#ifdef __APPLE__
#include "TargetConditionals.h"
#ifdef TARGET_OS_MAC
#include <GLUT/glut.h>
#include <OpenGL/OpenGL.h>
#endif
#elif defined _WIN32 || defined _WIN64
#include <GL\glut.h>
#endif
It depends on the compiler. #ifdef __APPLE__ works for gcc.
According to Microsoft, _WIN32 will cover both the 32-bit and 64-bit versions of Windows. And __APPLE__ works for Clang (at least in Mavericks). So one correct way to write the ifdefs above is:
#ifdef __APPLE__
DoSomething();
#elif _WIN32
DoSomethingElse();
#else
GenerateErrorOrIgnore
Small correction: #ifdef TARGET_OS_MAC will get you always true on both OS X and iOS, as it is defines either 0 or 1 depending on platform, but when APPLE is defined, TARGET_OS_MAC is defined as well, so checking it inside the #ifdef APPLE is worthless.
You might want to use #if TARGET_OS_MAC instead. Same for all TARGET_* macros.
This question already has answers here:
How do I check OS with a preprocessor directive?
(16 answers)
Closed 3 years ago.
The community reviewed whether to reopen this question 6 months ago and left it closed:
Original close reason(s) were not resolved
If there's some cross-platform C/C++ code that should be compiled on Mac OS X, iOS, Linux, Windows, how can I detect them reliably during preprocessor process?
There are predefined macros that are used by most compilers, you can find the list here. GCC compiler predefined macros can be found here.
Here is an example for gcc:
#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__)
//define something for Windows (32-bit and 64-bit, this part is common)
#ifdef _WIN64
//define something for Windows (64-bit only)
#else
//define something for Windows (32-bit only)
#endif
#elif __APPLE__
#include <TargetConditionals.h>
#if TARGET_IPHONE_SIMULATOR
// iOS, tvOS, or watchOS Simulator
#elif TARGET_OS_MACCATALYST
// Mac's Catalyst (ports iOS API into Mac, like UIKit).
#elif TARGET_OS_IPHONE
// iOS, tvOS, or watchOS device
#elif TARGET_OS_MAC
// Other kinds of Apple platforms
#else
# error "Unknown Apple platform"
#endif
#elif __ANDROID__
// Below __linux__ check should be enough to handle Android,
// but something may be unique to Android.
#elif __linux__
// linux
#elif __unix__ // all unices not caught above
// Unix
#elif defined(_POSIX_VERSION)
// POSIX
#else
# error "Unknown compiler"
#endif
The defined macros depend on the compiler that you are going to use.
The _WIN64 #ifdef can be nested into the _WIN32 #ifdef because _WIN32 is even defined when targeting the Windows x64 version. This prevents code duplication if some header includes are common to both
(also WIN32 without underscore allows IDE to highlight the right partition of code).
As Jake points out, TARGET_IPHONE_SIMULATOR is a subset of TARGET_OS_IPHONE.
Also, TARGET_OS_IPHONE is a subset of TARGET_OS_MAC.
So a better approach might be:
#ifdef _WIN64
//define something for Windows (64-bit)
#elif _WIN32
//define something for Windows (32-bit)
#elif __APPLE__
#include "TargetConditionals.h"
#if TARGET_OS_IPHONE && TARGET_OS_SIMULATOR
// define something for simulator
// (although, checking for TARGET_OS_IPHONE should not be required).
#elif TARGET_OS_IPHONE && TARGET_OS_MACCATALYST
// define something for Mac's Catalyst
#elif TARGET_OS_IPHONE
// define something for iphone
#else
#define TARGET_OS_OSX 1
// define something for OSX
#endif
#elif __linux
// linux
#elif __unix // all unices not caught above
// Unix
#elif __posix
// POSIX
#endif
Note that above checks TARGET_OS_SIMULATOR macro because TARGET_IPHONE_SIMULATOR macro got deprecated since iOS 14.
5 Jan 2021: link update thanks to #Sadap's comment.
Kind of a corollary answer: the people on this site have taken the time to make tables of macros defined for every OS/compiler pair.
For example, you can see that _WIN32 is NOT defined on Windows with Cygwin (POSIX), while it IS defined for compilation on Windows, Cygwin (non-POSIX), and MinGW with every available compiler (Clang, GNU, Intel, etc.).
Anyway, I found the tables quite informative and thought I'd share here.