Question

I thought this question was asked before but I tried Google but didn’t find an answer. Maybe I used wrong keywords.

Is it possible to use regular expression to match valid C# namespace name?

---

Update:

Thanks everyone for your answers and research! This question is much more complex than I expected. As Oscar Mederos and Joey pointed out, a valid namespace cannot contain C# reserved keywords, and can contain a lot more Unicode characters than Latin letters.

But my current project only need to syntactically validate namespaces. So I accepted primfaktor‘s answer, but I upvoted all answers.

Answer 1

For me, this worked:

^using (@?[a-z_A-Z]\w+(?:\.@?[a-z_A-Z]\w+)*);$

It matches using lines in C# and returns the complete namespace in the first (and only) match group. You may want to remove ^ and $ to allow for indentation and trailing comments.

Example on RegExr.