regex - Regular expression doesn't match if a character participated in a previous match -

i have regex:

(?:\s)\++(?:\s) 

which supposed catch pluses in query string this:

?busca=tenis+nike+categoria:"tenis+e+squash"&pagina=4&operador=or 

it should have been 4 matches, there 3:
s+n
e+c
s+e

it missing last one:
e+s

and seems happen because "e" character has participated in previous match (s+e), because "e" character right in middle of 2 pluses (teni s+e+s quash).

if test regex following input, matches last "+":

?busca=tenis+nike+categoria:"tenis_e+squash"&pagina=4&operador=or 

(changed "s+e" "s_e" in order not cause "e" character participate in match).

would please shed light on that?

thanks in advance!

you correct: fourth match doesn't happen because surrounding character has participated in previous match. solution use lookaround (if regex implementation supports - javascript doesn't support lookbehind, example).

try

(?<!\s)\++(?!\s) 

this matches 1 or more + unless surrounded whitespace. works if plus @ start or end of string.

explanation:

(?<!\s)  # assert there no space before current position          # (but don't make character part of match itself) \++      # match 1 or more pluses (?!\s)   # assert there no space after current position 

if regex implementation doesn't support lookbehind, use

\s\++(?!\s) 

that way, match contain character before plus, not after it, , therefore there no overlapping matches (thanks gumbo!). fail match plus @ start of string, though (because \s need match character). not problem.