getting wether OS is 32-bit or 64-bit - c++

Question

getting information if operating system is 32-bit or 64-bit from Qt Framework, to be portable on different OS's
I can get from Qt information wether the application has been build for as 32 or 64-bit (QSysInfo::buildCpuArchitecture()) or wether the CPU is 32 or 64-bit (QSysInfo::currentCpuArchitecture()), the operating system name(QSysInfo::prettyProductName()) but I haven't find how to determine if the operating system is 32 or 64-bit with Qt (should be portable!).
Is there any function in Qt to get that information?
Thanks for your time.
qDebug() << "QSysInfo::buildCpuArchitecture():" << QSysInfo::buildCpuArchitecture();
qDebug() << "QSysInfo::currentCpuArchitecture():" << QSysInfo::currentCpuArchitecture();
qDebug() << "QSysInfo::buildAbi():" << QSysInfo::buildAbi();
qDebug() << "QSysInfo::prettyProductName():" << QSysInfo::prettyProductName();
// the result with MinGW 32-bit:
// QSysInfo::buildCpuArchitecture(): "i386"
// QSysInfo::currentCpuArchitecture(): "x86_64"
// QSysInfo::buildAbi(): "i386-little_endian-ilp32"
// QSysInfo::prettyProductName(): "Windows 10"
// the result with VC++ 64-bit:
// QSysInfo::buildCpuArchitecture(): "x86_64"
// QSysInfo::currentCpuArchitecture(): "x86_64"
// QSysInfo::buildAbi(): "x86_64-little_endian-llp64"
// QSysInfo::prettyProductName(): "Windows 10"

Answer 1

Although the name suggests otherwise, currentCpuArchitecture does not tell you whether the CPU is 32bit or 64bit, but will tell you about the bitness of the operating system.
QString QSysInfo::currentCpuArchitecture()
Returns the architecture of the CPU that the application is running
on, in text format. Note that this function depends on what the OS
will report and may not detect the actual CPU architecture if the OS
hides that information or is unable to provide it. For example, a
32-bit OS running on a 64-bit CPU is usually unable to determine the
CPU is actually capable of running 64-bit programs.
http://doc.qt.io/qt-5/qsysinfo.html#currentCpuArchitecture

Answer 2

After many trials, I have found a solution, which gives also the right result with a 32-bit application an 64-bit Windows:
#if defined(Q_OS_WIN)
inline bool isWow64Process()
{
// https://learn.microsoft.com/en-us/windows/desktop/api/wow64apiset/nf-wow64apiset-iswow64process
typedef BOOL (WINAPI *LPFN_ISWOW64PROCESS) (HANDLE, PBOOL);
BOOL bIsWow64 = FALSE;
//IsWow64Process is not available on all supported versions of Windows.
//Use GetModuleHandle to get a handle to the DLL that contains the function
//and GetProcAddress to get a pointer to the function if available.
LPFN_ISWOW64PROCESS fnIsWow64Process = (LPFN_ISWOW64PROCESS) GetProcAddress(
GetModuleHandle(TEXT("kernel32")),"IsWow64Process");
if( NULL != fnIsWow64Process )
{
if (!fnIsWow64Process(GetCurrentProcess(), &bIsWow64))
{
// we couldn't get the pointer to the function,
// we assume that app is not running as
// WOW64 process and return therefore FALSE
bIsWow64 = FALSE;
}
}
return bIsWow64;
}
#endif // (_MSC_VER)
QString osInfo()
{
#if defined(Q_OS_WIN)
QString osBitness( QSysInfo::buildAbi().contains("ilp32") && !isWow64Process()? "32-bit" : "64-bit" );
return QString( QSysInfo::prettyProductName() + " - " + osBitness);
#else // we do not know how to get OS bitness on Linux and OS-X (we do not mean processor, neither application, but OS!)
return QSysInfo::prettyProductName();
#endif
}