Here is the code
string = "Looking for the ^[cows]"
footnote = string[/\^\[(.*?)\]/]
I was hoping that footnote would equal cows
What I get is footnote equals ^[cows]
Any help?
Thanks!
4 Answers
You can specify which capture group you want with a second argument to []:
string = "Looking for the ^[cows]"
footnote = string[/\^\[(.*?)\]/, 1]
# footnote == "cows"
1 Comment
crowhill
.match() might be a better solution in some cases, but this works best for me.
According to the String documentation, the #[] method takes a second parameter, an integer, which determines the matching group returned:
a = "hello there"
a[/[aeiou](.)\1/] #=> "ell"
a[/[aeiou](.)\1/, 0] #=> "ell"
a[/[aeiou](.)\1/, 1] #=> "l"
a[/[aeiou](.)\1/, 2] #=> nil
You should use footnote = string[/\^\[(.*?)\]/, 1]
Comments
If you want to capture subgroups, you can use Regexp#match:
r = /\^\[(.*?)\]/
r.match(string) # => #<MatchData "^[cows]" 1:"cows">
r.match(string)[0] # => "^[cows]"
r.match(string)[1] # => "cows"
Comments
An alternative to using a capture group, and then retrieving it's contents, is to match only what you want. Here are three ways of doing that.
#1 Use a positive lookbehind and a positive lookahead
string[/(?<=\[).*?(?=\])/]
#=> "cows"
#2 Use match but forget (\K) and a positive lookahead
string[/\[\K.*?(?=\])/]
#=> "cows"
#3 Use String#gsub
string.gsub(/.*?\[|\].*/,'')
#=> "cows"
^[cows], because that's what you are explicitly asking for in the pattern\^\[(.*?)\]. Thecowssubstring resides in the especial variable$1(group one). Be aware that string[regexp] will return the match of the entire pattern, not the groups.