Basic program to convert integer to Roman numerals?

Question

I want to create a program that will take a user-inputted integer and I want to convert it into its Roman numeral equivalent. What I have so far is:

Screenshot of my code:

I'm struggling with the main program. 

Right now my code doesn't even print anything.

Answer 1

You can deal with the problem with the help of the divmod function. You can check if the provided number matches any Roman numeral from the highest to the lowest. At every match, you should return the corresponding character.

You can use an OrderedDict so that you can iterate "downwards" the list, then I use a recursion of divmod to generate matches. Eventually, you can join all the generated answers to produce a string.

from collections import OrderedDict

def write_roman(num):

    roman = OrderedDict()

    roman[1000] = "M"

    roman[900] = "CM"

    roman[500] = "D"

    roman[400] = "CD"

    roman[100] = "C"

    roman[90] = "XC"

    roman[50] = "L"

    roman[40] = "XL"

    roman[10] = "X"

    roman[9] = "IX"

    roman[5] = "V"

    roman[4] = "IV"

    roman[1] = "I"

    def roman_num(num):

        for r in roman.keys():

            x, y = divmod(num, r)

            yield roman[r] * x

            num -= (r * x)

            if num <= 0:

                break

    return "".join([a for a in roman_num(num)])

Taking it for a spin:

num = 35

print write_roman(num)

# XXXV

num = 994

print write_roman(num)

# CMXCIV

num = 1995

print write_roman(num)

# MCMXCV

num = 2015

print write_roman(num)

# MMXV

For more information regarding the same, do refer to the Python online course that will help you out in a better way. 

If you want to know more about Python basics then do refer to the below Python tutorial: