Strings recipes for the Dart Cookbook

recipes/test/core/strings/using_raw_strings_test.dart

+library using_raw_strings_test;
+
+import 'package:unittest/unittest.dart';
+
+void main() {
+  var x = "asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf";
+  var y = "\u0061sdf";
+  var z = "asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf";
+  print(x == z);
+  print(identical(x, z));
+  print("$x, $z");
+  return;
+  
+  var string = '+1,';
+  var r = r'(\+|-)?\d+';
+  var r2 = '(\+|-)?\d+';
+  print("r = $r");
+  print("r2 = $r2");
+  print('When properly escaped: ' r'(\\+|-)?\\d+');
+  var regExp = new RegExp(r);
+  
+  print(regExp.firstMatch(string).group(0));
+  print(3.0 == 3.0000);
+}