Basic Syntax

// Variables
var name = 'John';
String greeting = 'Hello';
int age = 30;
double price = 19.99;
bool isActive = true;

// Null safety
String? nullableName;
String nonNullName = nullableName ?? 'Default';

// Functions
int add(int a, int b) => a + b;

void greet(String name, {int age = 0}) {
  print('Hello $name, age $age');
}

// Lists and Maps
List<String> fruits = ['apple', 'banana'];
Map<String, int> scores = {'Alice': 100, 'Bob': 85};

// Classes
class Person {
  String name;
  int age;
  
  Person(this.name, this.age);
  
  void introduce() {
    print('I am $name, $age years old');
  }
}

Collections

// Lists
var list = [1, 2, 3];
list.add(4);
list.remove(2);
list.forEach((item) => print(item));

// Sets
var uniqueNumbers = {1, 2, 3};
uniqueNumbers.add(1); // No duplicate

// Maps
var person = {'name': 'John', 'age': 30};
person['email'] = 'john@example.com';

// Spread operator
var combined = [...list, ...uniqueNumbers];

// Collection if
var nav = ['Home', if (isLoggedIn) 'Logout'];

Async/Await

Future<String> fetchData() async {
  await Future.delayed(Duration(seconds: 2));
  return 'Data loaded';
}

void main() async {
  print('Loading...');
  var data = await fetchData();
  print(data);
}

// Streams
Stream<int> countStream() async* {
  for (int i = 1; i <= 5; i++) {
    await Future.delayed(Duration(seconds: 1));
    yield i;
  }
}

void listenToStream() async {
  await for (var value in countStream()) {
    print(value);
  }
}

Useful Features

• Strong typing with type inference
• Null safety by default
• Named and optional parameters
• Extension methods
• Mixins for code reuse
• Cascade notation (..) for chaining
• Collection literals with type inference