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

#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

Answer 2

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;
}

Answer 3

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.

Answer 4

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.

Answer 5

I did not find Haiku definition here. To be complete, Haiku-os definition is simple __HAIKU__

Answer 6

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