CODEWITHSUNDEEP
ruby
Aleks Gorbenko
Aleks Gorbenko

Reputation: 1

Method to convert roman numbers to arabic doesn't print the answer

I am creating a method that converts roman numbers to integers. I have written this:

def roman_to_integer(roman)
  roman = roman.upcase 

  num_I = roman.count("I").to_i 
  num_V = roman.count("V").to_i
  num_X = roman.count("X").to_i
  num_L = roman.count("L").to_i
  num_C = roman.count("C").to_i
  num_D = roman.count("D").to_i
  num_M = roman.count("M").to_i

  rom_num = { "I" => 1, 
              "V" => 5, 
              "X" => 10,
              "L" => 50,
              "C" => 100,
              "D" => 500,
              "M" => 1000 }

    while roman 
      if roman[0] == "M"
        integer = num_M * rom_num["M"] + num_D * rom_num["D"] + num_C * rom_num["C"] + num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]
      elsif roman[0] == "D"
        integer = num_D * rom_num["D"] + num_C * rom_num["C"] + num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]
      elsif roman[0] == "C"
        integer = num_C * rom_num["C"] + num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]
      elsif roman[0] == "L"
        integer = num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]
      elsif roman[0] == "X"
        integer = num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]
      elsif roman[0] == "V"
        integer = num_V * rom_num["V"] + num_I * rom_num["I"]
      elsif roman[0] == "I"
        integer = num_I * rom_num["I"]
      end
    end
    return integer
end

puts "Tell me any number in Roman System and I will convert it to the Arabic Number!"
number = gets.chomp
puts "Here is your number:"
puts(roman_to_integer(number))

When it comes to the final line, where it should print out the result, I just get the empty input line in the command line. I don't understand why it doesn't work and need some help in finding where the code is wrong.

Also if I use

puts number.roman_to_integer

as a last line, I get

private method "roman_to_integer" called on "":String (NoMethodError)

Any help would be appreciated.

Upvotes: 0

Views: 166

Answers (2)

Uri Agassi
Uri Agassi

Reputation: 37409

Your method does not return since it is stuck in the while roman block - since you don't change the roman variable, it will always be truthy, and the block will continue to run over and over again, never returning a value:

while roman
  #... runs forever
end

Regardless of that, your method doesn't seem to do what you think it does ('IX' will return 1?)

Upvotes: 2

Sagar Pandya
Sagar Pandya

Reputation: 9497

Remove your while loop. I don't think it adds anything to the code. I've also improved formatting and removed the to_s methods which were superfluous.

def roman_to_integer(roman)

  roman = roman.upcase 

  # Counts the occurrences of each letter from the input

  num_I = roman.count("I") 
  num_V = roman.count("V")
  num_X = roman.count("X")
  num_L = roman.count("L")
  num_C = roman.count("C")
  num_D = roman.count("D")
  num_M = roman.count("M")

  # Assigns values to every Roman letter

  rom_num = { "I" => 1, 
              "V" => 5, 
              "X" => 10,
              "L" => 50,
              "C" => 100,
              "D" => 500,
              "M" => 1000 }

    # Multiplies the value of the letter by number of occurrences          


  if roman[0] == "M"
    integer  = num_M * rom_num["M"] + num_D * rom_num["D"] + num_C * rom_num["C"] + num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]
  elsif roman[0] == "D"
    integer = num_D * rom_num["D"] + num_C * rom_num["C"] + num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]

  elsif roman[0] == "C"
    integer = num_C * rom_num["C"] + num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]

  elsif roman[0] == "L"
    integer = num_L * rom_num["L"] + num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]

  elsif roman[0] == "X"
    integer = num_X * rom_num["X"] + num_V * rom_num["V"] + num_I * rom_num["I"]

  elsif roman[0] == "V"
    integer = num_V * rom_num["V"] + num_I * rom_num["I"]

  elsif roman[0] == "I"
    integer = num_I * rom_num["I"]
  end

  return integer
end

puts "Tell me any number in Roman System and I will convert it to the Arabic Number!"

number = gets.chomp
puts "Here is your number:"
puts roman_to_integer(number)

Also to make puts number.roman_to_integer work you would have to add your method to the String class, which you shouldn't do by the way.

Upvotes: 0

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