Regular expression for valid filename

Question

I already gone through some question in StackOverflow regarding this but nothing helped much in my case.

I want to restrict the user to provide a filename that shoul

Answer 1

This is a minor change to Engineers answer.

string regex = @"^[\w\- ]+[\w\-. ]*$"

This will block ".txt" which isn't valid.

Trouble is, it does block "..txt" which is valid