Regex with all optional parts but at least one required

Question

I need to write a regex that matches strings like \"abc\", \"ab\", \"ac\", \"bc\", \"a\", \"b\", \"c\". Order is important and it shouldn\'t match multiple appearances of th

Answer 1

It is pointless to try to pack all functionality of all problems you ever have into one single regexp. The best solution is to write the obvious regex, and add a check against zero length. You should only get extra clever with regexps when you absolutely have to - for instance if you have to interact with an unchangeable API that accepts only one regexp and nothing more.