Programming-Idioms

std::regex re("\\b\\d{3}\\b");
auto it = std::sregex_iterator(s.begin(), s.end(), re);
std::string x = it == std::sregex_iterator() ? "" : it->str();

string x = Regex.Match(s, @"\b\d\d\d\b").Value;

var re = new Regex(@"\b\d\d\d\b");
string x = re.Match(s).Value;

re := regexp.MustCompile(`\b\d\d\d\b`)
x := re.FindString(s)

const matches = s.match(/\b\d{3}\b/);
const x = matches ? matches[0] : '';

Matcher m = compile("\\b\\d{3}\\b").matcher(s);
String x = m.find() ? m.group() : "";

  with TRegExpr.Create do
  begin
    Expression := '\b\d\d\d\b';
    Exec(s);
    x := Match[0];
    Free;
  end;

my ($x) = $s =~ /\b(\d{3})\b/;

m = re.search(r'\b\d\d\d\b', s)
x = m.group(0) if m else ''

x = s.match(/\b\d{3}\b/).to_s

let re = Regex::new(r"\b\d\d\d\b").expect("failed to compile regex");
let x = re.find(s).map(|x| x.as_str()).unwrap_or("");