Similarly to the directive:
#if defined(__linux__)
....
#else
...
#endif
used to switch from something for Linux to something for other O.S., how can I set in C++ to switch from a Kit for Embedded System to a Kit for Desktop?
#if defined(...what instruction...)
?
I don't know if there is a define that every embedded system will have (I doubt there is one). However, you could always use your own defines like:
#define __IS_EMBEDDED__
or
#define __IS_DESKTOP__
and then check those at the appropriate places:
#if defined(__IS_EMBEDDED__)
...
#else
...
#endif
Depending on the system you build your software for, you can activate the appropriate defines. An elegant method to achieve this would be to pass the defines as compiler flags as suggested in the comment by #Murphy.
Related
While reading various C and C++ sources, I have encountered two macros __APPLE__ and __OSX__. I found plenty of use of __OSX__ in various codes, especially those originating from *BSD systems.
However, sometimes I find that testing __OSX__ only is not sufficient and I have to complete tests with __APPLE__ macro.
The Porting Command Line Unix Tools to Mac OS X guides specifies __APPLE__ and additionally __APPLE_CC__ but does not mention __OSX__.
The Porting from GCC guide says:
Use #ifdef __GNUC__ to wrap any GCC-specific code.
Use #ifdef __APPLE_CC__ to wrap any Mac OS X-specific code.
Again, no mention about __OSX__ macro.
What macro is predefined on Mac OS X platform and XCode development environment that should be used to distinguish OSX-specific code in C/C++ programs?
Where is the __OSX__ macro defined? Is it *BSD specific macro?
It all depends.
Each macro specifies something different in meaning.
See: https://developer.apple.com/library/mac/documentation/Porting/Conceptual/PortingUnix/compiling/compiling.html#//apple_ref/doc/uid/TP40002850-SW13
__APPLE__
This macro is defined in any Apple computer.
__APPLE_CC__
This macro is set to an integer that represents the version number of
the compiler. This lets you distinguish, for example, between compilers
based on the same version of GCC, but with different bug fixes or features.
Larger values denote later compilers.
__OSX__
Presumably the OS is a particular variant of OS X
So given the above definitions I would use __APPLE__ to distinguish apple specific code.
Here is a nice list of macros for operating systems.
There's little info on __OSX__ on the web. You'll be safe with __APPLE__.
I normally use __MACH__ for this. It's been defined since the earliest version of OS X (and even before, presumably).
If you want to exclude the possibility that you might be compiling for some other OS that uses the Mach kernel then you can use #scravy's suggestion of:
#if defined(__APPLE__) && defined(__MACH__)
Note also that if you're compiling generic C/C++ code, i.e. no Apple-speacific headers, so you are just interested in pre-defined compiler macros, you can check these as follows:
$ gcc -dM -E - < /dev/null | egrep -i 'os_|mac|apple'
#define __APPLE_CC__ 6000
#define __APPLE__ 1
#define __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ 120000
#define __ENVIRONMENT_OS_VERSION_MIN_REQUIRED__ 120000
#define __MACH__ 1
#define __VERSION__ "Apple LLVM 13.1.6 (clang-1316.0.21.2.3)"
#define __apple_build_version__ 13160021
Use
#if defined(__APPLE__) && defined(__MACH__)
to distinguish Apple operating systems.
You can further use TARGET_OS_MAC and TARGET_OS_IPHONE to distinguish between macOS and iOS.
Full example:
#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 */
#elif TARGET_OS_MAC == 1
/* macOS */
#endif
#endif
Regarding the question of "where does __OSX__ come from?":
Some on-line lists of compiler macros (like this one) list __MACOSX__. Some forum comments (like these) claim __OSX__ exists. These are incorrect. There are no such macros predefined by OSX compilers, but they may be defined by specific project Makefiles and platform-detector scripts like GNU autoconf.
Source: http://nadeausoftware.com/articles/2012/01/c_c_tip_how_use_compiler_predefined_macros_detect_operating_system
Update – the above link is broken, see version in web archive: https://web.archive.org/web/20180331065236/http://nadeausoftware.com/articles/2012/01/c_c_tip_how_use_compiler_predefined_macros_detect_operating_system#OSXiOSandDarwin
For anyone coming across this question >= 2019, I found there's a header "Availability.h".
In that header, are #defines like:
#define __MAC_10_0 1000
#define __MAC_10_1 1010
#define __MAC_10_2 1020
#define __MAC_10_3 1030
#define __MAC_10_4 1040
#define __MAC_10_5 1050
#define __MAC_10_6 1060
#define __MAC_10_7 1070
#define __MAC_10_8 1080
#define __MAC_10_9 1090
#define __MAC_10_10 101000
#define __MAC_10_10_2 101002
#define __MAC_10_10_3 101003
#define __MAC_10_11 101100
#define __MAC_10_11_2 101102
So you CAN tell if you're compiling on a particular MacOS platform.
See http://nadeausoftware.com/articles/2012/01/c_c_tip_how_use_compiler_predefined_macros_detect_operating_system#OSXiOSandDarwin
#ifdef __APPLE__
#include <TargetConditionals.h>
#if TARGET_OS_MAC
...
#endif /* TARGET_OS_MAC */
#endif /* __APPLE__ */
Note that __OSX__ does NOT exist, at least as of Xcode 9.
Also note that it is #if TARGET_OS_MAC not #ifdef. It is always defined, but is 0 when not macOS.
One can compile different code depending on the current Qt version:
#if QT_VERSION < 0x050000
.....
#else
.....
#endif
However, Qt4 and Qt5 have different macros for checking the operating system: Q_WS_WIN -> Q_OS_WIN and Q_WS_X11 -> Q_OS_LINUX, respectively. How to add #ifdef macro for certain operating system?
You do not need to use QT_VERSION, you can check both versions like this:
#if defined(Q_WS_WIN) || defined(Q_OS_WIN)
// Windows...
#elif defined(Q_WS_X11) || defined(Q_OS_LINUX)
// Linux...
#endif
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 work in Visual Studio but my project is for a POSIX-based environment (marmalade sdk). In this project, the release
build is compiled with gcc for ARM but the debug version works on windows and is compiled by MS compiler. Also this environmet has its own implementation of STL and other standard libraries.
Many of these c++ librares have code like this:
#if defined( _MSC_VER )
#include <Windows.h>
#else
#include <pthread.h>
#endif
Is it possible to undefine the _MSC_VER macro? - So that the C++ libraries will detect a POSIX system here.
_MSC_VER is (and always should be) defined when compiling with the Microsoft compiler so that it "evaluates to the major and minor number components of the compiler's version number". Therefore, the code is using the wrong macro test, since it will always be defined to some value for your compiler regardless of the Windows environment differences.
Rather than destroy the definition of _MSC_VER (which could lead to other problems if any code really does want to know the compiler version), what you really should do instead is to correct the condition so that a more appropriate macro test is used that distinguishes between the kinds of Windows environments that you might encounter.
See the more complete list of predefined macros you could consider here
You could either replace the condition ...
#if someOtherConditionGoesHere
... or extend it with additional conditions, e.g.
#if defined(_MSC_VER) && someOtherConditionGoesHere
Of course:
#undef _MSC_VER
#if defined( _MSC_VER )
#include <Windows.h>
#else
#include <pthread.h>
#endif
Or, #undef it before you include the file where _MSC_VER is used.
While reading various C and C++ sources, I have encountered two macros __APPLE__ and __OSX__. I found plenty of use of __OSX__ in various codes, especially those originating from *BSD systems.
However, sometimes I find that testing __OSX__ only is not sufficient and I have to complete tests with __APPLE__ macro.
The Porting Command Line Unix Tools to Mac OS X guides specifies __APPLE__ and additionally __APPLE_CC__ but does not mention __OSX__.
The Porting from GCC guide says:
Use #ifdef __GNUC__ to wrap any GCC-specific code.
Use #ifdef __APPLE_CC__ to wrap any Mac OS X-specific code.
Again, no mention about __OSX__ macro.
What macro is predefined on Mac OS X platform and XCode development environment that should be used to distinguish OSX-specific code in C/C++ programs?
Where is the __OSX__ macro defined? Is it *BSD specific macro?
It all depends.
Each macro specifies something different in meaning.
See: https://developer.apple.com/library/mac/documentation/Porting/Conceptual/PortingUnix/compiling/compiling.html#//apple_ref/doc/uid/TP40002850-SW13
__APPLE__
This macro is defined in any Apple computer.
__APPLE_CC__
This macro is set to an integer that represents the version number of
the compiler. This lets you distinguish, for example, between compilers
based on the same version of GCC, but with different bug fixes or features.
Larger values denote later compilers.
__OSX__
Presumably the OS is a particular variant of OS X
So given the above definitions I would use __APPLE__ to distinguish apple specific code.
Here is a nice list of macros for operating systems.
There's little info on __OSX__ on the web. You'll be safe with __APPLE__.
I normally use __MACH__ for this. It's been defined since the earliest version of OS X (and even before, presumably).
If you want to exclude the possibility that you might be compiling for some other OS that uses the Mach kernel then you can use #scravy's suggestion of:
#if defined(__APPLE__) && defined(__MACH__)
Note also that if you're compiling generic C/C++ code, i.e. no Apple-speacific headers, so you are just interested in pre-defined compiler macros, you can check these as follows:
$ gcc -dM -E - < /dev/null | egrep -i 'os_|mac|apple'
#define __APPLE_CC__ 6000
#define __APPLE__ 1
#define __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ 120000
#define __ENVIRONMENT_OS_VERSION_MIN_REQUIRED__ 120000
#define __MACH__ 1
#define __VERSION__ "Apple LLVM 13.1.6 (clang-1316.0.21.2.3)"
#define __apple_build_version__ 13160021
Use
#if defined(__APPLE__) && defined(__MACH__)
to distinguish Apple operating systems.
You can further use TARGET_OS_MAC and TARGET_OS_IPHONE to distinguish between macOS and iOS.
Full example:
#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 */
#elif TARGET_OS_MAC == 1
/* macOS */
#endif
#endif
Regarding the question of "where does __OSX__ come from?":
Some on-line lists of compiler macros (like this one) list __MACOSX__. Some forum comments (like these) claim __OSX__ exists. These are incorrect. There are no such macros predefined by OSX compilers, but they may be defined by specific project Makefiles and platform-detector scripts like GNU autoconf.
Source: http://nadeausoftware.com/articles/2012/01/c_c_tip_how_use_compiler_predefined_macros_detect_operating_system
Update – the above link is broken, see version in web archive: https://web.archive.org/web/20180331065236/http://nadeausoftware.com/articles/2012/01/c_c_tip_how_use_compiler_predefined_macros_detect_operating_system#OSXiOSandDarwin
For anyone coming across this question >= 2019, I found there's a header "Availability.h".
In that header, are #defines like:
#define __MAC_10_0 1000
#define __MAC_10_1 1010
#define __MAC_10_2 1020
#define __MAC_10_3 1030
#define __MAC_10_4 1040
#define __MAC_10_5 1050
#define __MAC_10_6 1060
#define __MAC_10_7 1070
#define __MAC_10_8 1080
#define __MAC_10_9 1090
#define __MAC_10_10 101000
#define __MAC_10_10_2 101002
#define __MAC_10_10_3 101003
#define __MAC_10_11 101100
#define __MAC_10_11_2 101102
So you CAN tell if you're compiling on a particular MacOS platform.
See http://nadeausoftware.com/articles/2012/01/c_c_tip_how_use_compiler_predefined_macros_detect_operating_system#OSXiOSandDarwin
#ifdef __APPLE__
#include <TargetConditionals.h>
#if TARGET_OS_MAC
...
#endif /* TARGET_OS_MAC */
#endif /* __APPLE__ */
Note that __OSX__ does NOT exist, at least as of Xcode 9.
Also note that it is #if TARGET_OS_MAC not #ifdef. It is always defined, but is 0 when not macOS.