python - Regex not start with dot or end with dot

Question

I need a regular expression that does not start with a dot or end with [-_.].

This regex works but fails for the first condition; it does not start with dot:

^[A-Za-z0-9][^.]*[^-_.][A-Za-z0-9]$

For example: test.com should be a valid string but it fails.

Answer 1

From your previous question, you should be able to use:

^[^.].*[^-_.]$

But if you want to be able to match a 1 character string, you will need negative lookaheads:

^(?![.])(?!.*[-_.]$).+

And if you want to match empty strings too, simply use * instead of +.

^(?![.])(?!.*[-_.]$).*