C++ get windows product id from registry

Question

I already searched the internet and found a lot of "solutions" which dont work for me :/

I have this:

HKEY keyHandle;
char rgValue[1024];
char fnlRes[1024];
DWORD size1;
DWORD Type;

if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion", 0, KEY_QUERY_VALUE | KEY_WOW64_64KEY, &keyHandle) == ERROR_SUCCESS)
{
    size1 = 1023;
    RegQueryValueEx(keyHandle, L"Productid", NULL, &Type, (LPBYTE)rgValue, &size1);
    sprintf_s(fnlRes, "Product ID of your Windows system is:: %s", rgValue);
}
else strcpy_s(fnlRes, "Couldn't access system information!");

RegCloseKey(keyHandle);

std::cout << fnlRes;

And I get this in console:

Answer 1

The reason is a character encoding mismatch. You are calling the Unicode version of RegQueryValueEx() but giving it an Ansi buffer to fill. Use WCHAR instead of char:

HKEY keyHandle;
WCHAR rgValue[1024];
WCHAR fnlRes[1024];
DWORD size1;
DWORD Type;

if (RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion", 0, KEY_QUERY_VALUE | KEY_WOW64_64KEY, &keyHandle) == ERROR_SUCCESS)
{
    size1 = 1023;
    RegQueryValueExW(keyHandle, L"Productid", NULL, &Type, (LPBYTE)rgValue, &size1);
    swprintf_s(fnlRes, L"Product ID of your Windows system is:: %s", rgValue);
    RegCloseKey(keyHandle);
}
else wcscpy_s(fnlRes, L"Couldn't access system information!");

wcout << fnlRes;