An expression is a special kind of statement that evaluates to a value. For example, 5 + 3; is an expression ending with a semicolon.

Every expression is composed of operators and operands.

• operands are representations of data.
• operators are defines how the operands will be processed to produce a result.

Operators:

• Arithmetic Operators : Dart supports the following arithmetic operators : +, -, *, /, %, ~/, ++, --.

• Comparison Operators : Dart supports the following comparison operators : ==, !=, >, <, >=, <=.

• Logical Operators : Dart supports the following logical operators : &&, ||, !.

• Assignment Operators : Dart supports the following assignment operators : =, +=, -=, *=, /=, %=, ~/=, <<=, >>=, &=, |=, ^=, ??=.

• Conditional Operators : Dart supports the following conditional operators : ??, ??=.

• Ternary Operator : Dart supports the ternary operator.

  condition ? expression1 : expression2;

Control Statements are used to control the flow of the program. There are three types of control statements in Dart :

• Conditional Statements
• Loop Statements
• Jump Statements

Conditional Statements:

Dart supports if, else if, else and switch statements.

• if statement
• else if statement
• else statement
• switch statement

Loop Statements:

A loop is a block of code that can be executed repeatedly. Dart supports for, while, and do while loops.

• for loop

  for (initialization; condition; increment/decrement) {
      //   block of code
  }

• while loop

  initialization
  while (condition) {
      //   block of code
      increment/decrement
  }

• do while loop

  initialization
  do {
      //   block of code
      increment/decrement
  } while (condition);

Jump Statements:

Dart supports break and continue statements.

• break is used to exit a loop.
• continue is used to skip an iteration in a loop.

• Add - add() addAll()
• Insert - insert() insertAll()
• Remove - remove() removeAt() removeLast() removeRange() removeWhere()
• Update - replaceRange() or manually list[index] = value
• Sort - sort()
• Length - length
• Clear - clear()

The Map is a collection of key-value pairs. Keys and values can be of any type. A Map is a dynamic collection. Maps can be declared in two ways :

• Using Map Literals

  var map = {
      "key1": "value1",
      "key2": "value2",
      "key3": "value3",
  }

• Using the Map constructor

  var map = new Map();
  map["key1"] = "value1";
  map["key2"] = "value2";
  map["key3"] = "value3";

• Operations on Map : addAll() containsKey() containsValue() forEach() remove() removeWhere() updateAll() clear() length isEmpty isNotEmpty

A set is a collection of unique elements. It is a dynamic collection.

Sets can be declared in two ways :

• Using Set Literals

  var set = {
      "value1",
      "value2",
      "value3",
  }

• Using the Set constructor

  var set = new Set();
  set.add("value1");
  set.add("value2");
  set.add("value3");

• Operations on Set : add() addAll() contains() remove() clear() length isEmpty isNotEmpty

Functions are a block of code that performs a specific task.

Functions can be 4 types :

• No Arguments and No Return Type

  void myFunction() {
      print("Hello World");
  }

• No Arguments and With Return Type

  int myFunction() {
      return 1;
  }

• With Arguments and No Return Type

  void myFunction(int a, int b) {
      print(a + b);
  }

• With Arguments and With Return Type

  int myFunction(int a, int b) {
      return a + b;
  }

Dart is an object-oriented language. It supports object-oriented programming features like classes, interfaces, inheritance, polymorphism, and encapsulation.

A class is a blueprint for creating objects. It defines the properties and behaviors that an object of that class will have.

An object is an instance of a class. It contains the state and behavior of the class.

• A class can defined by using class keyword.

• A class can have variables, functions, and objects.

  class Person {
      String name;
      int age;
      void printInfo() {
          print("Name: $name, Age: $age");
      }
  }
  
  var person = new Person(); // Create an object of the `Person` class
  
  person.name = "John"; // Set the name of the person
  person.age = 30; // Set the age of the person
  
  person.printInfo(); // Print the name and age of the person

• The this keyword refers to the current instance of the class. If the parameter name and the name of the class's property are the same, hence to avoid confusion, it is recommended to use the this keyword in Dart.

• A class can be defined in another file and imported in the main file.

  class Person {
      String name;
      int age;
      void printInfo() {
          print("Name: $name, Age: $age");
      }
  }

• The Person class is defined in another file and imported in the main file.

  import 'person.dart';
  
  void main() {
      Person person = new Person();
      person.name = "John";
      person.age = 30;
      person.printInfo();
  }

• A class can inherit the properties and methods of another class.

• Inheritance is a mechanism in which one class acquires the properties and methods of another class.

• The extends keyword is used to inherit the properties and methods from another class.

• The super keyword is used to access the properties and methods of the parent class.

• The super keyword is used to call the parent class's constructor.

  // Parent class
  class Person {
      String name;
      int age;
      void printInfo() {
          print("Name: $name, Age: $age");
      }
  }
  
  // Child class
  class Employee extends Person {
  String department;
      // Constructor
      Employee(String name, int age, String department) {
          this.name = name;
          this.age = age;
          this.department = department;
      }
      // Override the `printInfo()` method
      @override
      void printInfo() {
          super.printInfo();
          print("Department: $department");
      }
  }
  
  // Main class
  void main() {
      Employee employee = new Employee("John", 30, "IT");
      employee.printInfo();
  }