Question

I’m trying to find a regexp that only matches strings if they don’t contain a dot, e.g. it matches stackoverflow, 42abc47 or a-bc-31_4 but doesn’t match: .swp, stackoverflow or test..

Answer 1

^[^.]*$

or

^[^.]+$

Depending on whether you want to match empty string. Some applications may implicitly supply the ^ and $, in which case they’d be unnecessary. For example: the HTML5 input element’s pattern attribute.

You can find a lot more great information on the regular-expressions.info site.