Why does (?:\s)\w{2}(?:\s) not match only a 2 letter sub string with spaces around it not the spaces as well?

Question

I am trying to make a regex that matches all sub strings under or equal to 2 characters with a space on ether side. What did I do wrong?

ex what I want to do is have it match %2 or q but not 123 and not the spaces.

update this \b\w{2}\b if it also matched one letter sub strings and did not ignore special characters like - or #.

Answer 1

You should use

(^|\s)\S{1,2}(?=\s)

Since you cannot use a look-behind, you can use a capture group and if you replace text, you can then restore the captured part with $1.

See regex demo here

Regex breakdown:

• (^|\s) - Group 1 - either a start of string or a whitespace
• \S{1,2} - 1 or 2 non-whitespace characters
• (?=\s) - check if after 1 or 2 non-whitespace characters we have a whitespace. If not, fail.