Roman Numeral in Go

Published on 28 April 2022 (Updated: 25 September 2022)

Roman Numeral in Go

Welcome to the Roman Numeral in Go page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

package main

import "fmt"
import "os"

func exitWithError(msg string) {
	fmt.Println(msg)
	os.Exit(1)
}

func toRoman(input string) (total int) {
	var i = 0
	var temp1 int
	var temp2 int

	var numerals = map[string]int{
		"I": 1,
		"V": 5,
		"X": 10,
		"L": 50,
		"C": 100,
		"D": 500,
		"M": 1000,
	}

	//While i is within bounds of input
	for i < len(input) {
		//Get the current value
		temp1 = numerals[string(input[i])]
		if temp1 == 0 {
			exitWithError("Error: invalid string of roman numerals")
		}

		//If we still have input left to compare, check if we need to
		//	subtract from the next value
		if len(input) > i+1 {
			//Get the next value
			temp2 = numerals[string(input[i+1])]
			if temp2 == 0 {
				exitWithError("Error: invalid string of roman numerals")
			}

			//If the current value is >= next, use it's mapped value
			if temp1 >= temp2 {
				total += temp1
				i++
				//Otherwise, adjust for the subtraction and skip next
			} else {
				total += temp2 - temp1
				i += 2
			}
			//Otherwise, just add the current value to the total
		} else {
			total += temp1
			i++
		}
	}
	return
}

func main() {
	//Args or die
	if len(os.Args) != 2 {
		exitWithError("Usage: please provide a string of roman numerals")
	}

	roman := toRoman(os.Args[1])
	fmt.Printf("%d\n", roman)
}

Roman Numeral in Go was written by:

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of Apr 01 2019 02:39:00. The solution was first committed on Oct 25 2018 20:18:29. As a result, documentation below may be outdated.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.