#!/usr/bin/env ruby
# coding: utf-8
Encoding.default_external = 'utf-8'
require 'csv'
CSV.open("output.csv", "w") do |csv|
  csv << ["a", "b", "c"]
  csv << [1,2,3]
  csv << "あいう".split("")     # ["あ", "い", "う"] の配列を追加
end