Regular Expressions: Positive Lookahead and Word Border question

Question

Hello again Stackoverflow people!

Assume I have these words: smartphones, smartphone

I want to match the substring "phone" from within them. However, in both case, I want only "phone" to be returned, not "phones" in the first case. In addition to this, I want matches only if the word "phone" is a suffix only, such that:

fonephonetics (just an example) is not matched.

I assumed that the regex

(phone([?=s])?)\b

would give me what I need, but it is currently matching "phones" and "phone", but not the "fonephonetics" one. I don't need "phones". I want "phone" for both cases.

Any ideas about what is wrong, and what I can do?

Thank you in advance!

Answer 1

To match phone followed by either s\b or \b:

phone(?=s?\b)

The lookahead is a zero-width match so the s won't be returned as part of the match.