Armstrong Numbers

armstrong.rb

#!/usr/bin/env ruby

# Coding challenge : Armstrong Numbers
#
# Write a program using any language or technique that can accept two positive
# integers defining a range (such as 0 and 100 for the range 0 <= x <= 100) and
# will print all Armstrong Numbers in that range.
#
# An Armstrong Number is fully defined at
# http://en.wikipedia.org/wiki/Narcissistic_number
#
# In short it is any number where the value is the same as the sum of it's
# digits raised to the power of the number of it's digits.
#
# So 153 = 1^3 + 5^3 + 3^3
#
# Given the range 0 to 10,000 you should have the following output:
# 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371, 407, 1634, 8208, 9474
#
# We are assuming base 10.

low = ARGV[0]
high = ARGV[1]

(low..high).each do |num|
  digits = num.to_s.split('').to_a
  num_digits = digits.length
  result = 0

  digits.each do |digit|
    result += (digit.to_i**num_digits)
  end

  puts num if result.to_i == num.to_i
end