How can I check OS version (Windows) with preprocessor directives?

Question

I would like to know if there is any chance to check which Windows version I really use. Something similar to: How do I check OS with a preprocessor directive?.

I tried code from MSDN:

1. http://msdn.microsoft.com/en-us/library/windows/desktop/ms724451(v=vs.85).aspx
2. http://msdn.microsoft.com/en-us/library/windows/desktop/ms724439(v=vs.85).aspx

But any of them gave me good results (for example: according to http://msdn.microsoft.com/en-us/library/windows/desktop/ms724832(v=vs.85).aspx my code should print 5.1 when Im on Windows XP but it showed 5 ...)

Is there any reliable way (I would prefer preprocessor directives way) to find out which Windows I'm using?

My code:

#include <windows.h>
#include <iostream>

int main()
{
    OSVERSIONINFO osvi;
    BOOL bIsWindowsXPorLater;

    ZeroMemory(&osvi, sizeof(OSVERSIONINFO));
    osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);

    GetVersionEx(&osvi);

    // I HAD THIS, AND IT WAS WRONG! :<
    std::cout << osvi.dwMajorVersion << "\n";

    // CHANGED THE ABOVE LINE TO THE LINE BELOW AND IT IS OK NOW :D
    std::cout << osvi.dwMajorVersion << "." << osvi.dwMinorVersion << "\n";


    return 0;
}

Answer 1

You are actually getting the right result. But you are only printing the major version:

std::cout << osvi.dwMajorVersion << "\n";

Instead try using:

if (osvi.dwMinorVersion >= 1) {
     std::cout << osvi.dwMajorVersion << "." << osvi.dwMinorVersion << std::endl;
} else {
     std::cout << osvi.dwMajorVersion << std::endl;
}