Checks the difference between two files

check_difference.rb

# To run, cd to this folder and put the following command in the command line
# ruby check_difference.rb

require 'set'

# Returns the user ids for emails that already exist
class Difference
  FILE_ONE = 'all_emails.txt'.freeze
  FILE_TWO = 'matched_emails.txt'.freeze

  def check
    all_emails = Set.new
    matched_emails = Set.new

    File.open(FILE_ONE).each do |line|
      all_emails.add(line)
    end

    File.open(FILE_TWO).each do |line|
      matched_emails.add(line)
    end

    diff = all_emails - matched_emails
    puts diff.to_a
  end
end

Difference.new.check