If the function succeeds, the return value is an open handle to a specified file. If a specified file exists before the function call and dwCreationDisposition is CREATE_ALWAYS or OPEN_ALWAYS, a call to GetLastError returns ERROR_ALREADY_EXISTS, even when the function succeeds. If a file does not exist before the call, GetLastError returns 0 (zero).
If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.
