#define SYSTEM_VERSION_REG_KEY "SOFTWARE//Microsoft//Windows NT//CurrentVersion"
#define SYSTEM_CURRENT_VER_VAR "CurrentVersion"
HKEY hKey;
LONG lRet = RegOpenKeyEx(HKEY_LOCAL_MACHINE, SYSTEM_VERSION_REG_KEY, 0, KEY_READ, &hKey );
DWORD dwBufSize = MAX_PATH;
//get value for product name
UCHAR szAppPath[MAX_PATH] = {0};
RegQueryValueEx(hKey, SYSTEM_CURRENT_VER_VAR, NULL, NULL,
szAppPath, &dwBufSize)
RegCloseKey(hKey);