in reply to unable to monitor file size change with win32::changenotify

The biggest problem is that you are trying to monitor a file; when I try to do that with this code, I get the same error that you do. If, however, you specify only a directory at the prompt in your program, you will get a little further.

Of course when you get that far, you will discover that your program prints both "Nothing Changed" and "Something Changed" if nothing has changed. You might want to look into your logic a little further.