Regex - finding all 3 letter words - unexpected outcome

Question

Using regexpal.com to practice my regular expressions. I decided to start simply and ran into a problem.

Say you want to find all 3 letter words.

\\s\\w{         


        

Answer 1

(?<=\s)\w{3}(?=\s)

Overlapping spaces. Use 0 width assertions instead.When you use \s\w{3}\s on " abc acd " the regex engine consumes abc so the only thing left is acd which your regex will not match.So use lookaround to just assert and not consume.

EDIT:

\b\w{3}\b

Can also be used.

\b==>assert position at a word boundary (^\w|\w$|\W\w|\w\W)

or

(?:^|(?<=\s))\w{3}(?=\s|$)

This will find your 3 letter word even if it is at start or in middle or at end.