// 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)^(?=.{3,20}$)[a-zA-Z0-9]+(?:_[a-zA-Z0-9]+)+$").unwrap();
let string = "// should match
test_test_test_tests
test_test_test_tests
t_t_t_t_t_t_t_t_t_ts
t_t
// length 21
test_test_test_tests1
test_test_test_tests2
t_t_t_t_t_t_t_t_t_ts3
// length 2
t_
// underscore at start and end
test_test_test_test_
_est_test_test_tests
// double underscore
t_t_t_t_t__t_t_t_t_t";
// result will be an iterator over tuples containing the start and end indices for each match in the string
let result = regex.captures_iter(string);
for mat in result {
println!("{:?}", mat);
}
}
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/