main.rs

extern crate regex;

use std::io::{Write, stderr};

use regex::{Regex, Captures};

type Error = Box<::std::error::Error + Send + Sync>;

fn captures<'t>(pat: &str, txt: &'t str) -> Result<Vec<Captures<'t>>, Error> {
    let re = try!(Regex::new(pat));
    Ok(re.captures_iter(txt).collect())
}

fn main() {
    let caps = match captures(r"(\d+)", "aa 11 bb 22 cc 33") {
        Ok(caps) => caps,
        Err(err) => {
            writeln!(&mut stderr(), "ERROR: {}", err).unwrap();
            ::std::process::exit(1);
        }
    };
    for cap in &caps {
        println!("{:?}", cap.at(1));
    }
}