|There is no
GetUsbDriveLetter function in any Windows API (I don't know that function and a quick search did not found it too). Especially it can't be defined in winbase.h because that declares only plain Win32 functions which does not know the
Also, please don't post the same question at multiple places. I suggest that you delete the duplicate in the ATL / WTL / STL Discussion Boards[^]. Even this forum is not the correct one. The C / C++ / MFC board would have been a better choice.