#!/usr/bin/env ruby
# This code comes from http://ruby-it.org/pages/Espressioni+Regolari+Alternanza
# Check the page for copyright notice and explanations



 >> rgx= /ciao|bau|miao/
 => /ciao|bau|miao/
 >> 'ciao'=~ rgx
 => 0
 >> 'bau'=~ rgx
 => 0
 >> 'bao'=~ rgx
 => nil
 >> 'miao'=~ rgx
 => 0
 >> 'mao'=~ rgx
 => nil

 >> rgx= /(c|m)iao/
 => /(c|m)iao/
 >> 'miao'=~ rgx
 => 0
 >> 'ciao'=~ rgx
 => 0
 >> 'biao'=~ rgx
 => nil

 >> m=rgx.match 'ciao'
 => #<MatchData:0x27bc2e8>
 >> m[0]
 => "ciao"
 >> m[1]
 => "c"

 >> rgx= /(c)(i)(ao)/
 => /(c)(i)(ao)/
 >> m=rgx.match 'ciao'
 => #<MatchData:0x2758538>
 >> m[1]
 => "c"
 >> m[2]
 => "i"
 >> m[3]
 => "ao"

 >>  'ciao' =~ rgx
 => 0
 >> $1
 => "c"
 >> $2
 => "i"
 >> $3
 => "ao"