Parses numbers from a file and tells you which third they are in.

parse_average_sponsors.rs

use std::io::BufRead;
use std::{env, io};
use std::error::Error;
use std::ffi::OsString;
use std::fs::File;

fn get_first_arg() -> Result<OsString, Box<dyn Error>> {
    match env::args_os().nth(1) {
        None => Err(From::from("expected 1 argument, but got none")),
        Some(file_path) => Ok(file_path),
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let file_path = get_first_arg()?;
    let file = File::open(file_path)?;
    let reader = io::BufReader::new(file);

    let mut segments: [u32; 3] = [0, 0, 0];

    for line in reader.lines() {
        let value = line.unwrap().parse::<u8>().unwrap();
        if value < 34 {
            segments[0] += 1;
        } else if value < 67 {
            segments[1] += 1;
        } else {
            segments[2] += 1;
        }
    }

    println!("{}, {}, {}", segments[0], segments[1], segments[2]);

    Ok(())
}