A Regexp class is used to create Regular expressions in Ruby

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

 Regexp.new(string [, options [, lang]]) => regexp

for more detail goto : http://ruby-doc.org/core/classes/Regexp.html#M001198