regex notes

—

Look ahead positive A(?=B) — look for pattern A if followed by pattern B
Look ahead negative A(?!B) — look for pattern A if not followed by pattern B
Look behind positive (?<=B)A —- look for pattern A if preceded by pattern B
Look behind negative (?<!B)A —- look for pattern A if not preceded by pattern B
escape characters: \s space \S not space \d digit \D not digit \w word \W not word \r return \t tab

Comments