In Words With Recursion

In Words With Recursion.rb

require 'rspec'

module InWords

  def in_words
    #conditional statements
    a = if self == 1_000_000_000_000
      "one trillion"
    elsif self >= 1_000_000_000    #self is greater to or equal to 1 Billion
      prefix = self / 1_000_000_000
      suffix = self - (prefix * 1_000_000_000)
      prefix.in_words_by_100 + " billion " + suffix.in_words
    elsif self >= 1_000_000   #self is greater to or equal to 1 Million
      prefix = self / 1_000_000
      suffix = self - (prefix * 1_000_000)
      prefix.in_words_by_100 + " million " + suffix.in_words
    elsif self >= 1_000   #self is greater to or equal to 1 thousand
      prefix = self / 1_000
      suffix = self - (prefix * 1_000)
      prefix.in_words_by_100 + " thousand " + suffix.in_words
    else
      self.in_words_by_100
    end
    a.split.join(' ')
  end

  def in_words_by_100()
    single= {0=>"",1=>"one",2=>"two",3=>"three",4=>"four",5=>"five",6=>"six", 7=>"seven",8=>"eight",9=>"nine"}
    teens = {11=>"eleven",12=>"twelve",13=>"thirteen",14=>"fourteen",15=>"fifteen",16=>"sixteen", 17=>"seventeen",18=>"eighteen",19=>"nineteen"}
    tens = {0=>"",1=>"ten",2=>"twenty",3=>"thirty",4=>"forty",5=>"fifty",6=>"sixty", 7=>"seventy",8=>"eighty",9=>"ninety"}

    if self<10
      single[self]
    elsif self.between?(11,19)
      teens[self]
    elsif self.between?(19,99)
      tens[self/10] + " " + single[self%10]
    elsif self%100 < 10 && self< 1000
      single[self/100] + " hundred " + single[self%100]
    elsif self%100 < 20 && self < 1000
      single[self/100] + " hundred " + teens[self%100]
    elsif self%100 >= 20 && self < 1000
      single[self/100] + " hundred " + tens[(self/10)%10] + " " + single[(self%100)%10]
    else
      puts self
      puts "Error"
    end
  end
end

class Fixnum
  include InWords
end

describe Fixnum do
  describe "in_words" do
    it "translates numbers less than ten" do
      4.in_words.should == "four"
    end
    it "translates the teens" do
      17.in_words.should == "seventeen"
    end
    it "translates numbers 20 through 99" do
      47.in_words.should == "forty seven"
      70.in_words.should == "seventy"
      77.in_words.should == "seventy seven"
    end
    it "translates numbers 100 through 999" do
      100.in_words.should == "one hundred"
      206.in_words.should == "two hundred six"
      613.in_words.should == "six hundred thirteen"
      992.in_words.should == "nine hundred ninety two"
    end
    it "translates one thousand up to one million" do
      1_000.in_words.should == "one thousand"
      1_849.in_words.should == "one thousand eight hundred forty nine"
      15_937.in_words.should == "fifteen thousand nine hundred thirty seven"
      352_947.in_words.should == "three hundred fifty two thousand nine hundred forty seven"
    end
    it "translates numbers one million up to one billion" do
     # 1_000_000.in_words.should == "one million"
      573_917_408.in_words.should == "five hundred seventy three million nine hundred seventeen thousand four hundred eight"
    end
    it "translates numbers one billion up to one trillion" do
      1_000_000_000.in_words.should == "one billion"
      719_471_920_483.in_words.should == "seven hundred nineteen billion four hundred seventy one million nine hundred twenty thousand four hundred eighty three"
    end
    it "translates one trillion" do
      1_000_000_000_000.in_words.should == "one trillion"
    end
  end
end