Strange regex exception with fullstop

Question

I am using

^(?i)(?=.*\bWORD_TO_FIND\b).*$

In this specific case I am trying to match "S.A.M."

This way it works:

^(?i)(?=.*\bs.a.m\b).*$

This way it doesn't:

^(?i)(?=.*\bs.a.m.\b).*$

Why does that fullstop brakes the match?

You don't need the lookahead assertion for this. And you should regex quote the find word(s). And you should use a boundary with qualification. You could use a conditional boundary `"(?i)^.*(?(?=\\w)\\b)(?:" + regexQuote(text) + ")(?(?<=\\w)\\b).*$"` or, the best way is to use a whitespace boundary `"(?i)^.*(?<!\\S)(?:" + regexQuote(text) + ")(?!\\S).*$"` — , Nov 18 '15 at 17:10

score 1 · Answer 1 · answered Nov 18 '15 at 14:56

1

That is because of \b or word boundary.After . there is no \b or word boundary but after m there is.

^(?i)(?=.*\bs\.a\.m\.\b).*$

                    ^^
                  Here no word boundary so assertion or lookahead fails.

You should also be escaping . if you want to match .

answered Nov 18 '15 at 14:56

vks

Thanks, what other symbols should I escape? – user2468425 Nov 18 '15 at 15:03
@user2468425 all metacharacters that have special meaning in regex like `.*?{}` etc. – vks Nov 18 '15 at 15:04
@user2468425 do accept if it worked for you – vks Nov 18 '15 at 15:36
I'm sorry but it doesn't work for me – user2468425 Nov 18 '15 at 15:42
@user2468425 what doesnt work?see here https://regex101.com/r/hE4jH0/13 for java you need to use `^(?i)(?=.*\\bs\\.a\\.m\\b).*$` – vks Nov 18 '15 at 15:43

1 Answers1