A program that can interact with the operating system irrespective of the OS on which it runs.
Most of the compilers of c/c++ have the power to define macros that detect OS.
Some Macros of GCC compiler are −
_WIN32: macros for 32 bit and 64-bit Windows OS.
_WIN64: macros for 64-bit Windows OS.
_UNIX: macros for UNIX OS.
_APPLE_: macros for macOS.
Based on these macros defined, let’s create a program that will work irrespective of the OS −
Example
#include <iostream>
using namespace std;
int main() {
#ifdef _WIN32
system("dir");
#else
system("ls");
#endif
return 0;
}Output
This lists all files of the directory to the output screen irrespective of OS.