How to detect macOS version?

Question

I am trying to build a lib for macOS and Linux. The reason I am writing is to know how to detect macOS 11+ and Linux in a header file.

I have the structure on cmake, and it's building, but the os.h header is not building.

How can I detect with #ifdefs whether my code is on macOS Big Sur+ vs Red Hat? I am working on both sides.

I tried to use #ifdefs without success. This lib made with cmake is a proprietary code. I read a lot here about the subject without success. Can you help me?

My os.h:

#ifndef OS_H
#define OS_H

#include <iostream>
#include <sys/stat.h>
#include <sys/types.h>

#include <stdlib.h>
#include <map>
#include <string>
#include <sstream>
#include <vector>
#include <cstring>
#include <vector>
#include <fstream>
#include <ctype.h>

// os detection version
#ifdef Q_OS_LINUX
  std::cout << "Linux version";
#elif defined(Q_OS_CYGWIN)
  std::cout << "Cygwin version";
#else
#error "We don't support that version yet..."
#endif

#ifdef _WIN32 // Includes both 32 bit and 64 bit
        #ifdef _WIN64
            printf("Windows 64 bit\n");
        #else
            printf("Windows 32 bit\n");
        #endif
#elif __linux__
    printf("Linux\n");
#elif __unix__
    printf("Other unix OS\n");
#else
    printf("Unidentified OS\n");
#endif

#if __APPLE__
        #include "TargetConditionals.h"
        #if TARGET_OS_IPHONE && TARGET_IPHONE_SIMULATOR
            printf("iPhone stimulator\n");
        #elif TARGET_OS_IPHONE
            printf("iPhone\n");
        #elif TARGET_OS_MAC
            printf("MacOS\n");
        #else
            printf("Other Apple OS\n");
        #endif
    #else
        printf("Not an Apple OS\n");
    #endif

#if __linux__
        // linux optimized code (will fail in other platforms)
    #else
        // general code for all platforms
    #endif
    // general code

using namespace std;

#endif // OS_H

I cannot get this straight. My issue is somewhere. It's my first time with os flags. I am not used to this.

Note: there is no formal link between the compiler version and the OS your code is running on or even being compiled on. Cross-compilers confuse everything. — Botje, Apr 05 '23 at 09:15
Take a step back and explain why you need to detect OS versions _during the compilation process_ as opposed to at runtime? — Botje, Apr 05 '23 at 09:15
I use `#if defined(__GNUC__) && !defined(__llvm__)` to divert to rhel, and `#if defined(__APPLE__)` for mac. There are other ways, but that works for me. I use the gcc toolchain on both - although clang is switched in for the mac build. I only do this once in my entire codebase in case something messes up those switches. I then rely on my own proprietary symbols. — Bathsheba, Apr 05 '23 at 09:18
I am trying to detect os version over runtime. I know it's hard and confusing. I am trying to do this because I want to port for RED HAT under a cmake. Trying to avoid two compilations. Maybe, I will detect it to run on docker or podman. Perhaps I will do both versions. If things are not straight I will compile for both. — Pedro Vicente, Apr 05 '23 at 09:19
What does "trying to avoid two compilations" mean? MacOS and Linux have fundamentally different executable formats. — Botje, Apr 05 '23 at 09:29
Never mind. I wanted to say two compilations with the same code. Thanks — Pedro Vicente, Apr 05 '23 at 09:37
You need to compile separately for Mac and for Linux. A Mac binary cannot run on Linux and vice versa. — Jabberwocky, Apr 05 '23 at 09:42
But can I detect it on my header os.h? With the flags are showing here? — Pedro Vicente, Apr 05 '23 at 09:45
What's wrong with `#if defined(__APPLE__) //you're compiling for Mac #else you're not compiling for Mac #endif`. Also you write _"I tried to use ifdefs without success."_: [edit] and show what you've tried. — Jabberwocky, Apr 05 '23 at 09:49
I had a #error instruction and didn't work. For instance, if I build on my both machines with cmake, they work. But this #error is giving me a warning. I can't bypass them. — Pedro Vicente, Apr 05 '23 at 09:51
@PedroVicente please [edit] and share all details in the question. — Jabberwocky, Apr 05 '23 at 10:08
Clearly `Q_OS_LINUX` and `Q_OS_CYGWIN` are not defined when compiling for MacOS, which is why you hit the `#error`. You need another `#elif` branch to handle MacOS before reaching the `#error`. Or, just get rid of that whole `#ifdef`/`#elif` block completely, since you are using other `#if`s later in the file to handle the various platforms (including an `#elif` for `TARGET_OS_MAC`) — Remy Lebeau, Apr 05 '23 at 17:45

How to detect macOS version?

0 Answers0