Regexp
class Regexp
A Regexp holds a regular expression, used to match a pattern against strings. Regexps are created using the /.../ and %r{...} literals, and by the Regexp::new constructor.
Regular expressions (regexps) are patterns which describe the contents of a string. They're used for testing whether a string contains a given pattern, or extracting the portions that match. They are created with the /pat/ and %r{pat} literals or the Regexp.new constructor.
A regexp is usually delimited with forward slashes (/). For example:
/hay/ =~ 'haystack' #=> 0
/y/.match('haystack') #=> #