Regex - Does not contain certain characters except for end

Question

I need to match any lines that end with "&" but does not contain "," or "&" in between.

a b c &

a, b, c, &

a & b, c &

a & b

I was able to get partial success by using:

^(?!.*,).*&.*$

and I got both:

a b c &
a & b

So I've tried it with

^(?!.*(,|&)).*&.*$

And I'm unable to get any matches. How can I modify my regex so I can only get abc & ? I am using .NET

Answer 1

Seems you should get what you need by using a negated character class, eg

^[^,&]*&\s*$

using the multiline flag.

You can replace \\s* by \\r? if you don't want to allow trailing spaces as suggested by revo.

You might also want to add the newline character to the negated character class ( [^,&\\n] ) if you are working with multiline text (instead of testing line for line) to avoid overlapping matches.