gistfile1.rb

class Compare
  def self.similar_between?(keeper, finder)
    finder_scan = finder.scan(/./)
    keeper_scan = keeper.scan(/./)
    
    same = []
    keeper_scan.each_with_index{ |char, key| same << char if finder_scan[key] == char }
    same.join
  end
end

puts Compare.similar_between?("salamaner", "salt") # => sal