Get content between parenthesis from String object in Ruby

Question

I have a string like this:

Hi my name is John (aka Johnator).

What is the best way to get what comes between the parentheses (including the parentheses)?

Cade · Accepted Answer · 2012-05-14T23:25:27.467

36

You can use String#[] with a regular expression:

a = "Hi my name is John (aka Johnator)"
a[/\(.*?\)/]
# => "(aka Johnator)"

edited May 14 '12 at 23:25

answered May 14 '12 at 23:18

Cade

1

what do you get for `"Hi my name is John (aka Surprise Bat /\\(*)(*)/\\)"`? – dbenhur May 14 '12 at 23:34
@dbenhur half a Surprise Bat. `[/\(.*\)/]` will prevent the slaughter. – Cade May 14 '12 at 23:39
@Cade ok, but now we're hosed with `"Hi my name is John (aka Surprise Bat /\\(*)(*)/\\) and this is my friend William (aka Bill)"`. Regexp has a hard time with arbitrary nesting http://stackoverflow.com/a/133684/1074296. – dbenhur May 14 '12 at 23:46
5

@dbenhur Sure. But these are straw men. It also won't help with `(It's () hard () to () write () a ()( (regex) )() when () the () input () (can () be () anything!))` – Cade May 14 '12 at 23:56
1

@venkatareddy The question mark changes it from a greedy match, which will match until the last closing parenthesis, to a lazy match, which will match until the first closing parenthesis. You can read more about greedy vs. lazy matching here: http://www.regular-expressions.info/repeat.html#greedy – Cade Sep 18 '15 at 14:19

score 3 · Answer 2 · edited Oct 18 '19 at 10:53

3

Use [^()]*? for select text in parenthese :

a = "Hi (a(b)c) ((d)"
# => "Hi (a(b)c) ((d)"
a.gsub(/\([^()]*?\)/) { |x| p x[1..-2]; "w"}
"b"
"d"
# => "Hi (awc) (w"

edited Oct 18 '19 at 10:53

Sebastián Palma

answered May 15 '12 at 11:23

raubarede

score 1 · Answer 3 · answered May 14 '12 at 23:48

1

Try this:

str1 = ""
text = "Hi my name is John (aka Johnator)"

text.sub(/(\(.*?\))/) { str1 = $1 }

puts str1

Edit: Didn't read about leaving the parenthesis!

answered May 14 '12 at 23:48

Sheol

3 Answers3