Prime Number in Rust

Welcome to the Prime Number 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

//  Requirement     https://sample-programs.therenegadecoder.com/projects/prime-number/
// Accept a number on command line and print if it is Composite or Prime 
// Works till  39 digits, ...

use std::env::args;
use std::process::exit;
use std::str::FromStr;

fn usage() -> ! {
    println!("Usage: please input a non-negative integer");
    exit(0);
}

fn parse_int<T: FromStr>(s: &str) -> Result<T, <T as FromStr>::Err> {
    s.trim().parse::<T>()
}

fn main() {
    let mut args = args().skip(1);

    // Exit if 1st command-line argument not an positive integer
    let input_num: u128 = args
        .next()
        .and_then(|s| parse_int(&s).ok())
        .unwrap_or_else(|| usage());

    if input_num < 2 || (input_num != 2 && input_num % 2 == 0) {
        println!("Composite");
        exit(0);
    }

    let mut n = 3u128;
    while n * n <= input_num {
        if input_num % n == 0 {
            println!("Composite");
            exit(0);
        }
        n += 2;
    }
    println!("Prime");
}

Prime Number in Rust was written by:

• Mallikarjuna S J
• rzuckerm

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

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.