Hi,
tha attribute _A_SUBDIR comes from C++ CRT. If you are developing for Windows, you had better use Windows API functions and corresponding constants - see e.g.
MSDN File Attributes Constants.
Back to your question, I think there is no such attribute for EXE file or TXT files. But you can distinguish them by their suffix (.exe, .txt, ...). For some of these files (not all) thare are special validation rules, that you have to check to see if the content inside is really that of the file type. E.g. There is such a check for EXE files - when trying to excecute an EXE file, OS check validation rules to see if it is a valid EXE file - these rules are described in the
PE file Specification.
Hope this helps.
Best regards,
J.K.