Extract a substring from a string in Ruby using a

问题:

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 >).

回答1:

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.

回答2:

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

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

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

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

回答3:

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]

回答4:

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"

回答5:

A simpler scan would be:

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