Hello World in Dart

Introduction

Dart is the programming language behind Flutter, Google’s powerful cross-platform UI toolkit. If you are new to Dart, the best way to start learning is by writing a simple program, and nothing is more classic than a “Hello World” program.

In this guide, we will explore:

• How to write your first Dart program.
• Understanding Dart syntax and structure.
• Running Dart code in different environments.
• Modifying the Hello World program to make it interactive.
• Best practices for beginners.

By the end, you will have a strong foundation to start building Dart programs confidently.

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What is Dart?

Dart is a modern, object-oriented, strongly-typed programming language designed for fast development and high-performance applications. Key features include:

• Object-oriented syntax similar to Java or C#.
• Sound null safety for preventing runtime null errors.
• Asynchronous programming support with async and await.
• Cross-platform support for mobile, web, desktop, and server.

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Setting Up Dart Environment

Before writing your first program, you need to set up Dart.

Option 1: Using DartPad (Online)

• Visit https://dartpad.dev.
• This online IDE allows you to write and run Dart code without installing anything.
• Ideal for beginners to experiment.

Option 2: Installing Dart SDK Locally

1. Go to https://dart.dev/get-dart.
2. Download the SDK for your operating system (Windows/macOS/Linux).
3. Extract the SDK and add it to your system PATH.
4. Verify installation by running:

dart --version

Option 3: Using Visual Studio Code

• Install VS Code.
• Install Dart extension from the marketplace.
• Create a new Dart file (main.dart) and start coding.

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Writing Your First Dart Program

Step 1: Create a Dart File

Create a file named main.dart. This is the conventional entry point for Dart programs.

Step 2: Write Code

void main() {
  print('Hello, World!');
}

Step 3: Understanding the Code

• void main() – The main function where execution starts. Every Dart program requires a main function.
• print('Hello, World!'); – Prints the string Hello, World! to the console.
• ; – Marks the end of a statement.

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Running Your Dart Program

Using DartPad

• Paste the code into DartPad.
• Click Run.
• Output:

Hello, World!

Using Command Line

1. Open terminal and navigate to the directory containing main.dart.
2. Run:

dart run main.dart

3. The console will display:

Hello, World!

Using VS Code

1. Open the file in VS Code.
2. Press F5 or click Run → Start Debugging.
3. The console displays:

Hello, World!

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Making It Interactive

You can extend the Hello World program to accept input from users.

import 'dart:io';

void main() {
  stdout.write('Enter your name: ');
  String? name = stdin.readLineSync();
  print('Hello, $name!');
}

How It Works

• import 'dart:io'; – Imports the Input/Output library for console interaction.
• stdout.write() – Prints text without a newline.
• stdin.readLineSync() – Reads user input from the console.
• $name – String interpolation to include user input in the output.

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Adding Comments

Comments help explain your code. Dart supports:

// Single-line comment
/* Multi-line
   comment */

Example:

void main() {
  // This prints Hello World
  print('Hello, World!');
}

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Exploring Basic Dart Concepts

Even in a simple Hello World program, you can learn:

1. Variables

String greeting = 'Hello, World!';
print(greeting);

2. Functions

void sayHello(String name) {
  print('Hello, $name!');
}
sayHello('Ali');

3. Data Types

• String, int, double, bool

int age = 25;
double price = 9.99;
bool isActive = true;

4. Conditionals

if (age > 18) {
  print('Adult');
} else {
  print('Minor');
}

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Best Practices for Beginners

• Always use meaningful variable names.
• Add comments to explain logic.
• Start experimenting with small modifications to Hello World.
• Learn to run Dart programs in multiple environments (DartPad, terminal, VS Code).
• Gradually explore functions, loops, and classes.