需要在win7、windows server 2008、windows server 2012、win10上获取系统的版本号，综合了各类方法，最终代码如下所示，在4个平台可用。

#include <iostream>
#include <Windows.h>

#define REG_NT_VERSION "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion"

struct Info {
    char os_name[MAX_PATH];
    char installation[MAX_PATH];
    DWORD dwMajorVer, dwMinorVer, dwBuildNumber;
};

int get_os_info(Info& sysinfo, std::string& err) {
    HKEY hKey = NULL;
    LSTATUS lret = RegOpenKeyExA(
        HKEY_LOCAL_MACHINE,
        REG_NT_VERSION,
        0,
        KEY_READ,
        &hKey
    );
    if (lret != ERROR_SUCCESS) {
        char buf[1024];
        snprintf(buf, sizeof(buf), "RegOpenKeyExA error: %u", GetLastError());
        err = buf;
        return -1;
    }
    DWORD dwType = 0;
    DWORD dwSize = sizeof(sysinfo.os_name) / sizeof(sysinfo.os_name[0]);
    lret = RegQueryValueExA(hKey,
        "ProductName",
        NULL,
        &dwType,
        (LPBYTE)sysinfo.os_name,
        (DWORD*)&dwSize);
    if (lret != ERROR_SUCCESS) {
        char buf[1024];
        snprintf(buf, sizeof(buf), "RegQueryValueExA ProductName error: %u", GetLastError());
        err = buf;
        return -1;
    }
    dwSize = sizeof(sysinfo.installation) / sizeof(sysinfo.installation[0]);
    lret = RegQueryValueExA(hKey,
        "InstallationType",
        NULL,
        &dwType,
        (LPBYTE)sysinfo.installation,
        (DWORD*)&dwSize);
    if (lret != ERROR_SUCCESS) {
        char buf[1024];
        snprintf(buf, sizeof(buf), "RegQueryValueExA error: %u", GetLastError());
        err = buf;
        return -1;
    }
    RegCloseKey(hKey);

    BOOL bRet = FALSE;
    HMODULE hModNtdll = NULL;
    if (hModNtdll = ::LoadLibraryW(L"ntdll.dll"))
    {
        typedef void (WINAPI* pfRTLGETNTVERSIONNUMBERS)(DWORD*, DWORD*, DWORD*);
        pfRTLGETNTVERSIONNUMBERS pfRtlGetNtVersionNumbers;
        pfRtlGetNtVersionNumbers = (pfRTLGETNTVERSIONNUMBERS)::GetProcAddress(hModNtdll, "RtlGetNtVersionNumbers");
        if (pfRtlGetNtVersionNumbers)
        {
            pfRtlGetNtVersionNumbers(&sysinfo.dwMajorVer, &sysinfo.dwMinorVer, &sysinfo.dwBuildNumber);
            sysinfo.dwBuildNumber &= 0x0ffff;
            bRet = TRUE;
        }

        ::FreeLibrary(hModNtdll);
        hModNtdll = NULL;
    }
    if (!bRet) {
        char buf[1024];
        snprintf(buf, sizeof(buf), "get version error: %u", GetLastError());
        err = buf;
        return -1;
    }
    return 0;
}

int main()
{
    Info info = { 0 };
    std::string err;
    if (get_os_info(info, err)) {
        std::cerr << err << std::endl;
    }
    else {
        std::cout << "          OS: " << info.os_name << std::endl;
        std::cout << "Installation: " << info.installation << std::endl;
        std::cout << "    MajorVer: " << info.dwMajorVer << std::endl;
        std::cout << "    MinorVer: " << info.dwMinorVer << std::endl;
        std::cout << " BuildNumber: " << info.dwBuildNumber << std::endl;
    }
    char d;
    std::cin >> d;
    return 0;
}

采用VS2019编译。
win10上运行结果如下。

win10获取版本号.png

win7上结果如下。

win7获取版本号

windows server 2008上结果如下。

server 2008获取版本号

windows server 2012上结果如下。

server 2012获取结果