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Writing OS Independent Code in C/C++

A program that can interact with the operating system irrespective of the OS on which it runs. In simple words, we can say that a program, which can run on a computer without depending on the operating system.

How to write a utility program that lists all contents of the directory irrespective of the Operating System?
Most of the C/C++ compilers define macros that can be used to detect operating systems. For example, in GCC, the following are common macros. 

_WIN32 : Defined for both 32 bit and 64 bit windows OS.
_WIN64 : Defined for 64 bit windows OS.

unix, __unix, __unix__ : Defined in UNIX OS

__APPLE__, __MACH__ : Defined in Mac OS

In Windows, we use dir call to list all directories, and in most of the other Operating Systems “ls” is used. Below is a simple C++ implementation to list directories of folders irrespective of OS.




// C++ program to list all directories.
#include <bits/stdc++.h>
using namespace std;
int main()
{
#ifdef _WIN32
    system("dir");
#else
    system("ls");
#endif
    return 0;
}




// C program to list all directories.
#include <stdio.h>
 
int main()
{
#ifdef _WIN32
    system("dir");
#else
    system("ls");
#endif
    return 0;
}

Output:

bin
boot
dev
etc
home
lib
lib64
media
mnt
opt
proc
run
sbin
srv
sys
tmp
usr
var

The above OS-independent code is totally different from Java’s platform independence. In Java, there is intermediate byte code that is a very clean way of handling platform dependencies. Here we have to remember compiler-specific macros and write code using clumsy #ifdef and #else, and the most important, we need to recompile the code for every OS.
 

How to write 

Writing OS-independent code in C++ involves designing your code in a way that it can run on different operating systems without modification. Here are a few strategies that can help you write OS-independent code:

It’s important to note that while these strategies can help you write more portable code, it’s not always possible to write code that is completely OS-independent. Some functionality may not be available or may behave differently on different operating systems.

It’s also important to note that using platform-independent libraries and avoiding platform-specific libraries is not a foolproof method to make your code OS-independent. Sometimes, these libraries may have their own dependencies on operating system-specific functionality, and it’s always a good idea to check the documentation of the library to see how it behaves on different platforms.

Finally, it’s important to keep in mind that writing OS-independent code is not just about avoiding platform-specific functionality, but also about designing your code to be as modular and decoupled as possible. This makes it easier to adapt the code to different environments and to maintain it over time.

In summary, writing OS-independent code in C++ requires careful design and implementation, and it’s important to use platform-independent libraries, avoid platform-specific libraries, use preprocessor directives, use cross-platform build systems, use virtualization and containerization, and test on different operating systems. It’s also important to keep in mind that writing OS-independent code is not just about avoiding platform-specific functionality, but also about designing your code to be as modular and decoupled as possible.


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