# sample Ruby code to count vowels in input
# this uses just basic Ruby operations

def vowels_in_line(text)
  # downcase all letters, leaving the result in text
  text.downcase!
  # this could be written using a for loop, but that requires ranges
  vowels = 0
  i = 0
  while i < text.size
    ch = text[i]
    if ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u'
      vowels += 1
    end
    i += 1
  end
  return vowels
end

def main
  print "Enter lines of text, marking end-of-input with Control-Z on Windows "
  puts "and Control-D on OSX:"
  total_vowels = 0
  input_line = gets
  while input_line
    total_vowels += vowels_in_line(input_line)
    input_line = gets
  end
  puts "Number of vowels in input: #{total_vowels}"
end

main