Regex Find Whole Substring Between Parenthesis Containing Exact Substring

For example I have string: 'one two (78-45ack sack); now (87 back sack) follow dollow (59 uhhaaa)' and I need only whole substring with parenthesis, containing word 'back', for t

Solution 1:

You can use this regex based on negated character class:

\([^()]*?back[^()]*\)

• [^()]* matches 0 or more of any character that is not ( and ), thus making sure we don't match across the pair of (...).

RegEx Demo 1

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Alternatively, you can also use this regex based on negative regex:

\((?:(?!back|[()]).)*?back[^)]*\)

RegEx Demo 2

• (?!back|[()]) is negative lookahead that asserts that current position doesn't have back or ( or ) ahead in the text.
• (?:(?!back|\)).)*? matches 0 or more of any character that doesn't have back or ( or ) ahead.
• [^)]* matches anything but ).

Solution 2:

h="one two  (78-45ack sack); now (87 back sack) follow dollow (59 uhhaaa)"
l=h.split("(")
[x.split(")")[0] for x in l if ")" in x and "back" in x]

Solution 3:

Try the below pattern for reluctant matching

pattern="\(.*?\)"