Final Exercise from "Learning to Program" Chapter 9. This program changes inserted numbers to the Roman Numeral equivalent in two different styles.

gistfile1.rb

## Old Roman Style
def old_roman num
  m = ( num        ) / 1000
  d = ( num % 1000 ) / 500
  c = ( num % 500  ) / 100
  l = ( num % 100  ) / 50
  x = ( num % 50   ) / 10
  v = ( num % 10   ) / 5
  i = ( num % 5    )
  puts 'Old Roman Stlye: ' +
       ( 'M' * m ) +
       ( 'D' * d ) + 
       ( 'C' * c ) + 
       ( 'L' * l ) + 
       ( 'X' * x ) + 
       ( 'V' * v ) + 
       ( 'I' * i )
end

## New Roman Style
def new_roman num
  m = ( num        ) / 1000
  d = ( num % 1000 ) / 500
  c = ( num % 500  ) / 100
  l = ( num % 100  ) / 50
  x = ( num % 50   ) / 10
  v = ( num % 10   ) / 5
  i = ( num % 5    )

  iv = 0
  ix = 0
  xl = 0
  xc = 0
  cd = 0
  cm = 0

  if i == 4
    if v == 1
      ix = 1
    else
      iv = 1
    end
    v = 0
    i = 0
  end

  if x == 4
    if l == 1
      xc = 1
    else
      xl = 1
    end
    l = 0
    x = 0
  end

  if c == 4
    if d == 1
      cm = 1
    else
      cd = 1
    end
    d = 0
    c = 0
  end

  puts 'New Roman Stlye: ' +
       ( 'M'  *  m  ) + 
       ( 'CM' *  cm ) + 
       ( 'D'  *  d  ) + 
       ( 'CD' *  cd ) + 
       ( 'C'  *  c  ) + 
       ( 'XC' *  xc ) + 
       ( 'L'  *  l  ) + 
       ( 'XL' *  xl ) + 
       ( 'X'  *  x  ) + 
       ( 'IX' *  ix ) + 
       ( 'V'  *  v  ) + 
       ( 'IV' *  iv ) + 
       ( 'I'  *  i  )

end

## Keeps running until nothing is inserted
puts 'Type \'quit\' to...um...quit.'
while true
  puts 'Insert number to convert to Roman Numeral:'
  x = gets.chomp
  if x == 'quit'
    break
  elsif x.to_i != 0
    old_roman x.to_i
    new_roman x.to_i
    puts
  elsif x.to_i == 0
    puts
    puts 'ERROR'
    puts '----------------------------------------'
    puts 'Please insert a number larger than zero.'
    puts '----------------------------------------'
    puts
  else
    puts 'Please insert a number.'
  end
end