String str1 = 'Hello';//""
  String str2 = '''Hello
                  Dart''';//"""
  print(str1);
  print(str2);

//  String str3 = 'Hello n Dart';
  String str3 = r'Hello n Dart';
  print(str3);

Hello
Hello
                  Dart
Hello n Dart

  String str4 = "This is my favorite language";
  print(str4 + "New");
  print(str4 * 5);
  print(str3 == str4);
  print(str4[1]);

  int a = 1;
  int b = 2;
  print("a + b = ${a + b}");
  print("a = $a");

  print(str4.length);
  print(str4.isEmpty);

  print(str4.contains("This"));
  print(str4.substring(0,3));
  print(str4.startsWith("a"));
  print(str4.endsWith("ge"));

  var list = str4.split(" ");
  print(list);

  print(str4.replaceAll("This", "That"));

This is my favorite languageNew
This is my favorite languageThis is my favorite languageThis is my favorite languageThis is my favorite languageThis is my favorite language
false
h
a + b = 3
a = 1
28
false
true
Thi
false
true
[This, is, my, favorite, language]
That is my favorite language