what is the exact time that FileSystemWatcher raise Changed event

Question

I would like to understand the following: FileSystemWatcher raise Changed event when I open file and change it or just when I save the file after I change it?

If I using FileStream the change event will raise only when I do: fs.Close();

Answer 1

As far as the file system is concerned, a file is not "changed" until it is saved. If you open a text file in a word processor (from Notepad to Word) and start typing, the file hasn't actually "changed" yet; only the in-memory representation of the file that is specific to the word processor has changed.