Ruby Regular expression examples

```ruby # extract xxx text = "{{xxx}}" if text[/\{\{(.*)?\}\}/] xxx = $1 end # extract all headers from a raw Wikipedia article # example: # ==Banks== # ===Fraud=== # ===Corruption=== # \1 = back reference headers = text.scan(/^(={1,5})(.+?)\1$/m).inject([]) do |result, m| header = OpenStruct.new(:depth => m[0].length, :title => m[1]) result << header print (" "*header.depth) + header.title + "\n" result end ```