Roman Numeral in Rust

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

Current Solution

use std::env;

fn main() {
    let args: Vec<String> = env::args().collect();

    if args.len() < 2 {
        println!("Usage: please provide a string of roman numerals");
    } else {
        let value: i64 = convert_roman_numeral(&args[1]);
        if value < 0 {
            println!("Error: invalid string of roman numerals");
        } else {
            println!("{value}");
        }
    }
}

fn convert_char(c: char) -> i64 {
    if c == 'I' {
        return 1;
    } else if c == 'V' {
        return 5;
    } else if c == 'X' {
        return 10;
    } else if c == 'L' {
        return 50;
    } else if c == 'C' {
        return 100;
    } else if c == 'D' {
        return 500;
    } else if c == 'M' {
        return 1000;
    } else {
        return -1;
    }
}

fn convert_roman_numeral(s: &String) -> i64 {
    let mut number: i64 = 0;
    let mut prev_value: i64 = 0;
    for c in s.as_bytes() {
        let value = convert_char(*c as char);
        if value < 0 {
            number = value;
            break;
        }
        number += value;
        if prev_value > 0 && value > prev_value {
            number -= 2*prev_value;
            prev_value = 0;
        } else {
            prev_value = value;
        }
    }

    number
}

Roman Numeral in Rust was written by:

• Noah Nichols
• rzuckerm

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 04 2023 17:31:25. The solution was first committed on Oct 12 2018 18:00:40. As a result, documentation below may be outdated.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.