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arkirchner's solution

to Say in the Ruby Track

Published at Apr 18 2020 · 0 comments
Instructions
Test suite
Solution

Given a number from 0 to 999,999,999,999, spell out that number in English.

Step 1

Handle the basic case of 0 through 99.

If the input to the program is 22, then the output should be 'twenty-two'.

Your program should complain loudly if given a number outside the blessed range.

Some good test cases for this program are:

  • 0
  • 14
  • 50
  • 98
  • -1
  • 100

Extension

If you're on a Mac, shell out to Mac OS X's say program to talk out loud. If you're on Linux or Windows, eSpeakNG may be available with the command espeak.

Step 2

Implement breaking a number up into chunks of thousands.

So 1234567890 should yield a list like 1, 234, 567, and 890, while the far simpler 1000 should yield just 1 and 0.

The program must also report any values that are out of range.

Step 3

Now handle inserting the appropriate scale word between those chunks.

So 1234567890 should yield '1 billion 234 million 567 thousand 890'

The program must also report any values that are out of range. It's fine to stop at "trillion".

Step 4

Put it all together to get nothing but plain English.

12345 should give twelve thousand three hundred forty-five.

The program must also report any values that are out of range.

Extensions

Use and (correctly) when spelling out the number in English:

  • 14 becomes "fourteen".
  • 100 becomes "one hundred".
  • 120 becomes "one hundred and twenty".
  • 1002 becomes "one thousand and two".
  • 1323 becomes "one thousand three hundred and twenty-three".

For installation and learning resources, refer to the Ruby resources page.

For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:

gem install minitest

If you would like color output, you can require 'minitest/pride' in the test file, or note the alternative instruction, below, for running the test file.

Run the tests from the exercise directory using the following command:

ruby say_test.rb

To include color from the command line:

ruby -r minitest/pride say_test.rb

Source

A variation on JavaRanch CattleDrive, exercise 4a http://www.javaranch.com/say.jsp

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

say_test.rb

require 'minitest/autorun'
require_relative 'say'

# Common test data version: 1.2.0 a0cee46
class SayTest < Minitest::Test
  def test_zero
    # skip
    number = 0
    assert_equal "zero", Say.new(number).in_english
  end

  def test_one
    skip
    number = 1
    assert_equal "one", Say.new(number).in_english
  end

  def test_fourteen
    skip
    number = 14
    assert_equal "fourteen", Say.new(number).in_english
  end

  def test_twenty
    skip
    number = 20
    assert_equal "twenty", Say.new(number).in_english
  end

  def test_twenty_two
    skip
    number = 22
    assert_equal "twenty-two", Say.new(number).in_english
  end

  def test_one_hundred
    skip
    number = 100
    assert_equal "one hundred", Say.new(number).in_english
  end

  def test_one_hundred_twenty_three
    skip
    number = 123
    assert_equal "one hundred twenty-three", Say.new(number).in_english
  end

  def test_one_thousand
    skip
    number = 1_000
    assert_equal "one thousand", Say.new(number).in_english
  end

  def test_one_thousand_two_hundred_thirty_four
    skip
    number = 1_234
    assert_equal "one thousand two hundred thirty-four", Say.new(number).in_english
  end

  def test_one_million
    skip
    number = 1_000_000
    assert_equal "one million", Say.new(number).in_english
  end

  def test_one_million_two_thousand_three_hundred_forty_five
    skip
    number = 1_002_345
    assert_equal "one million two thousand three hundred forty-five", Say.new(number).in_english
  end

  def test_one_billion
    skip
    number = 1_000_000_000
    assert_equal "one billion", Say.new(number).in_english
  end

  def test_a_big_number
    skip
    number = 987_654_321_123
    assert_equal "nine hundred eighty-seven billion six hundred fifty-four million three hundred twenty-one thousand one hundred twenty-three", Say.new(number).in_english
  end

  def test_numbers_below_zero_are_out_of_range
    skip
    number = -1
    assert_raises(ArgumentError) do
      Say.new(number).in_english
    end
  end

  def test_numbers_above_999_999_999_999_are_out_of_range
    skip
    number = 1_000_000_000_000
    assert_raises(ArgumentError) do
      Say.new(number).in_english
    end
  end
end
require "pry"

=begin
Write your code for the 'Say' exercise in this file. Make the tests in
`say_test.rb` pass.

To get started with TDD, see the `README.md` file in your
`ruby/say` directory.
=end

class Say
  ONCE = %w[one two three four five six seven eight nine]
  TENCE = %w[teen twenty thirty forty fifty sixty seventy eighty ninety]

  def initialize(number)
    @number = number
  end

  def in_english
    return "zero" if number.zero?
    raise ArgumentError if  number > 999_999_999_999 || number < 0

    billion
  end

  private

  def once
    once_number = number % 10
    return if once_number.zero?

    ONCE[(number % 10) - 1]
  end

  def tence
    tence_number = number % 100
    return once if (tence_number / 10).zero?

    case tence_number
    when 11
      "eleven"
    when 12
      "twelve"
    else
      if tence_number / 10 == 1
        "#{once}#{TENCE[0]}"
      elsif (tence_number % 10).zero?
        TENCE[(tence_number / 10) - 1]
      else
        "#{TENCE[(tence_number / 10) - 1]}-#{once}"
      end
    end
  end

  def hundred
    hundred_number = (number % 1_000) / 100

    if hundred_number.zero?
      tence
    else
      if tence
        "#{ONCE[hundred_number -1]} hundred #{tence}"
      else
        "#{ONCE[hundred_number -1]} hundred"
      end
    end
  end

  def thousand
    thousand_number = (number % 1_000_000) / 1000

    if thousand_number.zero?
      hundred
    else
      self.class.new(thousand_number).in_english +
      if hundred
        " thousand #{hundred}"
      else
        " thousand"
      end
    end
  end

  def million
    million_number = (number % 1_000_000_000) / 1_000_000

    if million_number.zero?
      thousand
    else
      self.class.new(million_number).in_english +
      if thousand
        " million #{thousand}"
      else
        " million"
      end
    end
  end

  def billion
    billion_number = (number % 1_000_000_000_000) / 1_000_000_000

    if billion_number.zero?
      million
    else
      self.class.new(billion_number).in_english +
      if thousand
        " billion #{million}"
      else
        " billion"
      end
    end
  end


  attr_reader :number
end

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