Regex find whole substring between parenthesis con

Question

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 this string it will be:

"(87 back sack)"

I've tried:

(\(.*?back.*?\))

but it's return "(78-45ack sack); now (87 back sack)"

How should my regex look like? As I understood it's happening cause search going from begin of the string, in common - how to perform regex to "search" from the middle of string, from the word "back"?

Answer 1

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]

Answer 2

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 ).

Answer 3

Try the below pattern for reluctant matching

pattern="\(.*?\)"