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Author: lamek

src/content/get-started/ch1-hello-world.md

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+---
+title: Your first Dart program
+description: Create, run, and make your first change to a Dart command-line program.
+---
+
+Welcome to Dart. In this chapter, you'll ensure your setup is complete, and then
+be guided through creating your first Dart program. This chapter starts simple,
+but moves fast!
+
+:::secondary What you'll learn
+
+* Confirm your Dart SDK installation.
+* Use `dart create` to generate a new command-line interface (CLI) project.
+* Run your Dart program from the terminal using `dart run`.
+* Identify the `main` function as the program's entry point.
+* Make your first code change and see the updated output.
+
+:::
+
+## Prerequisites
+
+Before you begin this chapter, ensure you have:
+
+* Installed the Dart SDK.
+* Reviewed the Dart overview page (if you're new to Dart).
+
+## Task 1: Confirm your Dart setup
+
+First, make sure Dart is ready to go on your system by following these steps.
+
+1.  Open your terminal (or command prompt).
+
+2.  Run the following command to check your Dart SDK version:
+
+    ```bash
+    dart --version
+    ```
+
+3.  You should see output similar to this (the version numbers might be
+    different):
+
+    ```bash
+    Dart SDK version: 3.8.0 (stable) (None) on "linux_x64"
+    ```
+
+    If you see an error like "command not found," refer to the Dart
+    installation guide to set up your environment.
+
+## Task 2: Create a new Dart project
+
+Now, create your first Dart command-line application.
+
+1.  In your terminal, create a new directory called "dartpedia" to hold your
+    project. Then switch into that directory.
+
+    ```bash
+    mkdir dartpedia
+    cd dartpedia
+    ```
+
+2.  Run the following command:
+
+    ```bash
+    dart create cli
+    ```
+
+    This command uses the `dart create` command to generate a basic Dart project
+    named "cli" (for Command Line Interface). It sets up the essential files and
+    directories you need.
+
+3.  You should see output similar to this, confirming the project creation:
+
+    ```bash
+    Creating cli using template console...
+
+      .gitignore
+      analysis_options.yaml
+      CHANGELOG.md
+      pubspec.yaml
+      README.md
+      bin/cli.dart
+      lib/cli.dart
+      test/cli_test.dart
+
+    Running pub get...                     1.2s
+      Resolving dependencies...
+      Downloading packages...
+      Changed 49 dependencies!
+      1 package has newer versions incompatible with dependency constraints.
+      Try `dart pub outdated` for more information.
+
+    Created project cli in cli! In order to get started, run the following commands:
+
+      cd cli
+      dart run
+    ```
+
+    :::note
+    The `dart create` command created a number of files. Don't worry about these
+    now. Their specifics will be covered in future chapters.
+    :::
+
+## Task 3: Run your first Dart program
+
+1.  Navigate into your new project directory:
+
+    ```bash
+    cd cli
+    ```
+
+2.  Run the default application:
+
+    ```bash
+    dart run
+    ```
+
+    This command tells Dart to execute your program.
+
+3.  You should see the following output:
+
+    ```bash
+    Building package executable... 
+    Built cli:cli.
+    Hello world: 42!
+    ```
+
+    Congratulations! You've successfully run your first Dart program!
+
+## Task 4: Make your first code change
+
+Next, modify the code that generated `Hello world: 42!`.
+
+1.  Open the `bin/cli.dart` file in your editor.
+
+    The `bin/` directory is where your executable code lives. `cli.dart` is the
+    entry point of your application.
+
+    Inside, you'll see the `main` function. Every Dart program starts executing
+    from its `main` function.
+
+2.  Your `bin/cli.dart` should look like this:
+
+    ```dart
+    import 'package:cli/cli.dart' as cli;
+
+    void main(List<String> arguments) {
+      print('Hello world: ${cli.calculate()}!');
+    }
+    ```
+
+3.  Simplify the output for now. Comment out the first line (you don't need
+    this import statement), and change the `print` statement to display a simple
+    greeting:
+
+    ```dart
+    // import 'package:cli/cli.dart' as cli;
+
+    void main(List<String> arguments) {
+      print('Hello, Dart!'); // Change this line
+    }
+    ```
+
+    :::note
+    For now, comment out the `import 'package:cli/cli.dart'` line to avoid
+    an unused import warning. You will learn about this and fully remove the
+    line later.
+    :::
+
+4.  Save your file and run your program again:
+
+    ```bash
+    dart run
+    ```
+
+5.  You should now see:
+
+    ```bash
+    Building package executable... 
+    Built cli:cli.
+    Hello, Dart!
+    ```
+
+    You've successfully modified and re-run your first Dart program!
+
+## Review
+
+In this lesson, you:
+
+* Confirmed your Dart SDK installation.
+* Used `dart create` to generate a new CLI project.
+* Ran your Dart program from the terminal using `dart run`.
+* Identified the `main` function as the program's entry point within
+    `bin/cli.dart`.
+* Made your first code change and saw the updated output.
+
+## Quiz
+
+Here's a quick quiz to solidify your learning.
+
+:::note
+You'll see these quizzes throughout this tutorial. Feel free to skip them if you
+want.
+:::
+
+Which command is used to create a new Dart project from a template?
+
+* A) `dart new`
+* B) `dart build`
+* C) `dart create`
+* D) `dart init`
+
+## Next lesson
+
+In the next lesson, you'll learn how to make your program respond to specific
+commands by introducing command-line arguments and the `const` keyword.