// include the latest version of the regex crate in your Cargo.toml
extern crate regex;
use regex::Regex;
fn main() {
let regex = Regex::new(r"(?m)(?P<username>[a-zA-Z0-9.-_]+)@(?P<domain>[a-zA-Z0-9.-_]+)\.(?P<ltd>[a-zA-Z0-9-_]+)").unwrap();
let string = "The mail or post is a system for physically transporting postcards, letters, and parcels.[1] A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century,yvannak54@gmail.com national postal systems have generally been established as a government monopoly, with a fee on the article prepaid. Proof of payment is usually in the form of an adhesive postage stamp, but a it123@gmail.com postage meter is also used for bulk mailing. Modern private postal systems are distinguished from national postal agencies by the terms \"courier\" or \"delivery service\".
";
let substitution = "<a href=\"mailto:\\0\">${username}</a>";
// result will be a String with the substituted value
let result = regex.replace_all(string, substitution);
println!("{}", result);
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Rust, please visit: https://docs.rs/regex/latest/regex/