Dart: Scalable Application Development

Using regular expressions

Regular expressions are an indispensable tool in every programming language to search for matching patterns in strings. Dart has the RegExp class from dart:core, which uses the same syntax and semantics as JavaScript.

How to do it...

We use RegExp in the following code (see using_regexp.dart) to quickly determine whether a credit card number seems valid:

var visa = new RegExp(r"^(?:4[0-9]{12}(?:[0-9]{3})?)$");
var visa_in_text = new RegExp(r"\b4[0-9]{12}(?:[0-9]{3})?\b");
var input = "4457418557635128";
var text = "Does this text mention a VISA 4457418557635128 number?";

void main() {
  print(visa.pattern);
  // is there a visa pattern match in input?
  if (visa.hasMatch(input)) { print("Could be a VISA number"); } // does ...