CODEWITHSUNDEEP
rubyregexstringsubstring
Madhusudhan
Madhusudhan

Reputation: 8563

Extract a substring from a string in Ruby using a regular expression

How can I extract a substring from within a string in Ruby?

Example:

String1 = "<name> <substring>"

I want to extract substring from String1 (i.e. everything within the last occurrence of < and >).

Upvotes: 156

Views: 188073

Answers (5)

sepp2k
sepp2k

Reputation: 370455

String1.scan(/<([^>]*)>/).last.first

scan creates an array which, for each <item> in String1 contains the text between the < and the > in a one-element array (because when used with a regex containing capturing groups, scan creates an array containing the captures for each match). last gives you the last of those arrays and first then gives you the string in it.

Upvotes: 152

Nakilon
Nakilon

Reputation: 35112

"<name> <substring>"[/.*<([^>]*)/,1]
=> "substring"

No need to use scan, if we need only one result.
No need to use Python's match, when we have Ruby's String[regexp,#].

See: http://ruby-doc.org/core/String.html#method-i-5B-5D

Note: str[regexp, capture] → new_str or nil

Upvotes: 365

Navid
Navid

Reputation: 71

A simpler scan would be: 

String1.scan(/<(\S+)>/).last

Upvotes: 7

coreyward
coreyward

Reputation: 80140

You can use a regular expression for that pretty easily…

Allowing spaces around the word (but not keeping them):

str.match(/< ?([^>]+) ?>\Z/)[1]

Or without the spaces allowed: 

str.match(/<([^>]+)>\Z/)[1]

Upvotes: 26

Grant Birchmeier
Grant Birchmeier

Reputation: 18504

Here's a slightly more flexible approach using the match method. With this, you can extract more than one string:

s = "<ants> <pants>"
matchdata = s.match(/<([^>]*)> <([^>]*)>/)

# Use 'captures' to get an array of the captures
matchdata.captures   # ["ants","pants"]

# Or use raw indices
matchdata[0]   # whole regex match: "<ants> <pants>"
matchdata[1]   # first capture: "ants"
matchdata[2]   # second capture: "pants"

Upvotes: 12

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