#Lecture 02 — Dart SDK & Development Environment

You know what Dart is, but your computer does not understand it yet. Installing the Dart SDK and an editor turns your machine into a place where Dart code can run.

Contents

Prerequisites · Connection · Objectives · Lesson · Code Examples · Common Mistakes · Best Practices · Mini Challenge · Practice Questions · Answers · Takeaways

Every terminal output and error message in this lecture is real. Each one was produced on a Mac (Apple silicon) running Dart 3.12.1. The Windows and Linux install steps are described rather than shown, because their output looks different on every machine. Once Dart is installed, the dart commands behave the same on all three systems.

#Prerequisites

Students should already understand, from Lecture 001:

• what Dart is and what it is used for
• that a program is a set of instructions a computer follows

You also need a computer running Windows, macOS, or Linux, an internet connection, and permission to install software on it.

#Connection With Previous Lectures

In Lecture 001 we saw what Dart can do. But if you type a line of Dart into a plain text file today and ask your computer to run it, nothing happens — the computer has no idea what Dart is.

zsh:1: command not found: dart

That message is what a computer without Dart says when you ask for it. Before we can write our first program, we need two things: the tools that understand Dart, and a comfortable place to type code. This lecture installs both.

#Learning Objectives

By the end of this lecture you will be able to:

• Explain what the Dart SDK is and what it contains
• Open a terminal on your operating system
• Install the Dart SDK on Windows, macOS, or Linux
• Confirm the installation with dart --version
• Set up VS Code with the Dart extension
• Create a new project with dart create
• Run a project and a single file with dart run
• Recognize the messages Dart prints for common setup mistakes

#1. What Is the Dart SDK?

An SDK (Software Development Kit) is a bundle of everything you need to build programs in one language. The Dart SDK contains the dart command, the engine that runs Dart code, Dart's built-in libraries, and helper tools for formatting, checking, and testing code.

Analogy — the SDK is a workshop toolbox. You do not buy a hammer, a saw, and a screwdriver separately; you get one box, and every tool inside is made to work together. The dart command is the handle you use to pick up any tool in the box.

You will use exactly one command for everything in this course: dart.

#2. Opening a Terminal

A terminal is a window where you type commands instead of clicking buttons. All the commands in this lecture are typed there.

In this lecture, a line you type is shown in a bash block, and what the computer prints back is shown in a text block below it.

#3. Three Ways to Get Dart

The machine used to write this lecture got its Dart from Flutter. Either way, the dart command behaves the same. DartPad is handy, but it cannot create projects, so install the SDK for this course.

#4. Installing on Windows

The simplest route uses Chocolatey, a free package manager for Windows. After installing Chocolatey (see chocolatey.org), open PowerShell as Administrator and type:

choco install dart-sdk

If you prefer not to use Chocolatey, download the Windows SDK .zip from the Dart website (dart.dev/get-dart), extract it to a folder such as C:\tools\dart-sdk, and add C:\tools\dart-sdk\bin to your PATH. Search Start for "environment variables", open Edit environment variables for your account, select Path, click Edit → New, and paste the folder.

Close PowerShell and open a new one before continuing.

#5. Installing on macOS

On macOS, use Homebrew (see brew.sh if you do not have it yet). In Terminal:

brew tap dart-lang/dart
brew install dart

The first line tells Homebrew where Dart's packages live; the second installs the SDK. Homebrew puts dart on your PATH for you.

#6. Installing on Linux

On Ubuntu or Debian, add Google's Dart package source once, then install with apt:

sudo apt-get update && sudo apt-get install apt-transport-https
wget -qO- https://dl-ssl.google.com/linux/linux_signing_key.pub \
  | sudo gpg --dearmor -o /usr/share/keyrings/dart.gpg
echo 'deb [signed-by=/usr/share/keyrings/dart.gpg arch=amd64] https://storage.googleapis.com/download.dartlang.org/linux/debian stable main' \
  | sudo tee /etc/apt/sources.list.d/dart_stable.list
sudo apt-get update && sudo apt-get install dart

The package installs Dart under /usr/lib/dart. If dart is not found afterwards, add /usr/lib/dart/bin to your PATH. On other distributions, use the Linux .zip from dart.dev/get-dart. Install commands change over time, so if a line fails, copy the current version from that page.

#7. What PATH Means

When you type dart, your terminal searches a list of folders called the PATH for a program with that name. If the SDK's bin folder is not on that list, the terminal gives up:

dart --version

zsh:1: command not found: dart

On Windows PowerShell the wording is different (The term 'dart' is not recognized…), but the meaning is the same. The fix is always one of two things: add the SDK's bin folder to PATH, or simply open a new terminal — a terminal that was already open before the install still has the old list.

#8. Checking the Installation

This is the most important command in the lecture. Run it in a new terminal:

dart --version

Dart SDK version: 3.12.1 (stable) (Tue May 26 01:02:21 2026 -0700) on "macos_arm64"

Read it left to right: the version number, the stable release channel, the build date, and your platform — here, macOS on an ARM (Apple silicon) chip. On Windows you would see something like windows_x64. Any 3.12 version works for this course, and a newer one is fine too.

#9. Seeing What dart Can Do

The dart command contains many tools. Ask it to list them:

dart --help

A command-line utility for Dart development.

Usage: dart <command|dart-file> [arguments]
...
Available commands:
...
Project
  build       Build a Dart application including code assets.
  compile     Compile Dart to various formats.
  create      Create a new Dart project.
  pub         Work with packages.
  run         Run a Dart program from a file or a local or remote package.
  test        Run tests for a project.

Source code
  analyze     Analyze Dart code in a directory.
  doc         Generate API documentation for Dart projects.
  fix         Apply automated fixes to Dart source code.
  format      Idiomatically format Dart source code.
...

The list is trimmed here (...). Today we need only create and run. We will tour the rest in Lecture 113 — Dart CLI.

#10. Installing VS Code and the Dart Extension

You can write Dart in any text editor, but VS Code (free, from code.visualstudio.com) with the official Dart extension makes it far easier.

1. Download and install VS Code for your system.
2. Open the Extensions view: Ctrl + Shift + X (Windows/Linux) or Cmd + Shift + X (macOS).
3. Search for Dart and install the extension published by Dart Code.

The extension colors your code, underlines mistakes in red as you type, formats your code, and adds Run | Debug links above your program's starting point. VS Code also has a built-in terminal (View → Terminal), so you can run every command in this lecture without leaving the editor.

#11. Creating a Project with dart create

A project is a folder that holds a program's code and its settings. First move to a folder where you keep your work (for example, cd Documents), then run:

dart create hello_dart

Creating hello_dart using template console...

  .gitignore
  analysis_options.yaml
  CHANGELOG.md
  pubspec.yaml
  README.md
  bin/hello_dart.dart
  lib/hello_dart.dart
  test/hello_dart_test.dart

Running pub get...
  Resolving dependencies...
  Downloading packages...
  Changed 50 dependencies!

Created project hello_dart in hello_dart! In order to get started, run the following commands:

  cd hello_dart
  dart run

Dart created a folder called hello_dart, filled it with starter files, and downloaded the helper packages the project uses. That download needs an internet connection the first time.

#12. What's Inside the Project

Open the folder in VS Code with File → Open Folder…. These are the parts that matter now:

The starter program in bin/hello_dart.dart looks like this:

import 'package:hello_dart/hello_dart.dart' as hello_dart;

void main(List<String> arguments) {
  print('Hello world: ${hello_dart.calculate()}!');
}

Do not worry about what each word means yet. We will write our own program line by line in Lecture 003, study pubspec.yaml in Lecture 104, and write tests in Lecture 118 — Introduction to Testing.

#13. Running a Project with dart run

Move into the project folder and run it:

cd hello_dart
dart run

Hello world: 42!

Inside a project, a plain dart run finds the program in bin/ and runs it. The 42 comes from a small calculation in lib/hello_dart.dart.

#14. Running One File

dart run can also run a single file by name — inside a project or anywhere else. Save this as hello.dart in any folder:

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

dart run hello.dart

Hello, Dart!

A single file is perfect for quick experiments. A project is better once a program grows past one file.

#15. Changing the Program and Running Again

Programming is a loop: edit, save, run. Replace everything in bin/hello_dart.dart with:

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

Save the file (Ctrl + S / Cmd + S), then run the project again:

dart run

Hello, Ali!

In VS Code you can also click the Run link above void main(); the output appears in the editor's Debug Console panel instead of the terminal. Debugging itself is covered in Lecture 115 — Debugging Dart.

#16. A Real-World Example

Let's use the whole workflow once more. Sara wants a program that totals her shopping.

dart create shopping_total
cd shopping_total

Replace everything in bin/shopping_total.dart with:

void main() {
  print('Shopping list for Sara');
  print('Notebooks: 3 x 500');
  print('Pens: 4 x 50');
  print('Total:');
  print(3 * 500 + 4 * 50);
}

dart run

Shopping list for Sara
Notebooks: 3 x 500
Pens: 4 x 50
Total:
1700

That is the full cycle you will repeat for the rest of the course: create, edit, save, run, read the output.

#Code Examples

Each example is a command to type or a small program to save and run. Programs use only print(); Lecture 003 explains every line of them.

#Example 1 — Checking the Version

dart --version

Dart SDK version: 3.12.1 (stable) (Tue May 26 01:02:21 2026 -0700) on "macos_arm64"

Your version, date, and platform may differ. What matters is that you see a version instead of command not found.

#Example 2 — Getting Help

dart --help

A command-line utility for Dart development.

Usage: dart <command|dart-file> [arguments]
...

The first lines show the general shape of every dart command: the word dart, then a command or a file, then any extra details.

#Example 3 — Creating a Project

dart create first_app

Creating first_app using template console...
...
Created project first_app in first_app! In order to get started, run the following commands:

  cd first_app
  dart run

The project's folder takes the name you give. Dart even tells you the next two commands.

#Example 4 — Running a Project

cd first_app
dart run

Hello world: 42!

Every new console project prints this same line until you change it.

#Example 5 — Running a File Inside a Project by Path

dart run bin/first_app.dart

Hello world: 42!

Same result as Example 4. Here you named the file explicitly instead of letting Dart find it.

#Example 6 — A Single-File Program

Save as hello.dart:

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

dart run hello.dart

Hello, Dart!

No project needed: one file, one command.

#Example 7 — Student Marks

Save as marks.dart:

void main() {
  print('Ali, total marks:');
  print(80 + 75 + 85);
}

dart run marks.dart

Ali, total marks:
240

How it works

1. The first print shows the text between the quotes exactly as written.
2. The second print has no quotes, so Dart calculates 80 + 75 + 85 and shows 240.
3. Each print starts a new line.

#Example 8 — Shopping Total

Save as shopping.dart:

void main() {
  print('Notebooks: 3 x 500');
  print(500 * 3);
}

dart run shopping.dart

Notebooks: 3 x 500
1500

How it works

1. Inside quotes, 3 x 500 is just text — Dart does not calculate it.
2. In Dart code, multiplication is written with *, not x.
3. 500 * 3 is calculated and printed as 1500.

#Example 9 — Bank Balance

Save as balance.dart:

void main() {
  print('Balance after a 250 purchase:');
  print(1000 - 250);
}

dart run balance.dart

Balance after a 250 purchase:
750

How it works

1. The label is printed as text.
2. 1000 - 250 is calculated as 750.
3. Change 250 to another amount, save, and run again — the edit-save-run loop in action.

#Example 10 — Temperature Conversion

Save as temperature.dart:

void main() {
  print('25 degrees Celsius in Fahrenheit:');
  print(25 * 9 / 5 + 32);
}

dart run temperature.dart

25 degrees Celsius in Fahrenheit:
77.0

How it works

1. Dart multiplies and divides first: 25 * 9 / 5 is 45.
2. Then it adds 32, giving 77.
3. It prints 77.0 because division (/) always produces a decimal number. We will study whole and decimal numbers in Lecture 009 — Numbers.

#Common Beginner Mistakes

1. Using a terminal that was open before the install

dart --version

zsh:1: command not found: dart

Close the terminal and open a new one. If the message stays, the SDK's bin folder is not on your PATH — revisit the install step for your system.

2. Misspelling a command

dart versoin

Could not find a command named "versoin".

Usage: dart <command|dart-file> [arguments]

Dart lists the commands it does know right below this message. Check the spelling.

3. Running dart run outside the project folder

dart run

Found no `pubspec.yaml` file in `<your folder>` or parent directories

(Dart prints the full path of the folder you are in; it is shortened here.) A plain dart run needs a project. Use cd to move into the project folder first.

4. Mistyping a file name

dart run missing.dart

Could not find file `missing.dart`

Check the spelling, and check that you are in the folder that contains the file.

5. Creating a project whose folder already exists

dart create hello_dart

Directory '<your folder>/hello_dart' already exists (use '--force' to force project generation).

Choose a different name. Do not reach for --force — it can overwrite files you wrote.

6. Forgetting a semicolon after editing

Running this hello.dart:

// void main() {
//   print('Hello, Ali!')   ✗ missing ;
// }

hello.dart:2:22: Error: Expected ';' after this.
  print('Hello, Ali!')
                     ^

The error names the file, the line (2), and the column (22). Add the ; and run again.

7. Running before saving

If the output has not changed after an edit, you probably did not save. VS Code shows a dot on the file's tab when it has unsaved changes.

#Best Practices

• Always run dart --version in a new terminal right after installing.
• Install the official extension published by Dart Code — not a look-alike.
• Name projects in lowercase_with_underscores, such as shopping_total.
• Keep all your course projects together in one folder, so they are easy to find.
• Write your code in bin/; leave lib/ and test/ alone until later lectures.
• Save before every run — or turn on File → Auto Save in VS Code.
• Read error messages fully: they tell you the file, line, and column.

#Mini Challenge

Create a project called marks_report. Make it print exactly:

Student: Ali
Total marks:
240

The 240 must be calculated by Dart from the marks 80, 75, and 85, not typed in.

Try it yourself before opening the solution.

dart create marks_report
cd marks_report

void main() {
  print('Student: Ali');
  print('Total marks:');
  print(80 + 75 + 85);
}

dart run

Student: Ali
Total marks:
240

#Practice Questions

Work through these in order — they run from beginner to application to challenge.

Beginner

1. Which command shows the version of Dart installed on your computer?
2. Which command lists every tool the dart command contains?
3. Create a new console project named first_app. What command do you type?

Application

4. Run the first_app project without changing anything. What does it print?
5. Without creating a project, write and run a single file greeting.dart that prints Hello, Sara!.
6. Change first_app so that it prints Welcome, Zayan! instead of its starter message.
7. You type dart run and see Found no pubspec.yaml file in …. What went wrong, and how do you fix it?
8. Write and run a single file shopping.dart that calculates and prints the cost of 4 items at 250 each.

Challenge

9. Inside the first_app folder, run the program by naming its file directly rather than with a plain dart run.
10. A friend installs Dart, then types dart --version in a terminal that was already open and gets command not found. List the two things to check, in order.

#Practice Answers

#Question 1 — Solution

dart --version

Dart SDK version: 3.12.1 (stable) (Tue May 26 01:02:21 2026 -0700) on "macos_arm64"

Your own version, date, and platform will differ.

#Question 2 — Solution

dart --help

A command-line utility for Dart development.

Usage: dart <command|dart-file> [arguments]
...

#Question 3 — Solution

dart create first_app

Creating first_app using template console...
...
Created project first_app in first_app! In order to get started, run the following commands:

  cd first_app
  dart run

#Question 4 — Solution

cd first_app
dart run

Hello world: 42!

#Question 5 — Solution

Save as greeting.dart:

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

dart run greeting.dart

Hello, Sara!

#Question 6 — Solution

Replace everything in bin/first_app.dart with:

void main() {
  print('Welcome, Zayan!');
}

dart run

Welcome, Zayan!

#Question 7 — Solution

You ran dart run in a folder that is not a project. Move into the project folder first — for example, first_app after the change in Question 6:

cd first_app
dart run

Welcome, Zayan!

#Question 8 — Solution

Save as shopping.dart:

void main() {
  print(250 * 4);
}

dart run shopping.dart

1000

#Question 9 — Solution

dart run bin/first_app.dart

Welcome, Zayan!

It prints Welcome, Zayan! because of the change made in Question 6. Before that change, it would print Hello world: 42!.

#Question 10 — Solution

First, close the terminal, open a new one, and try again:

dart --version

Dart SDK version: 3.12.1 (stable) (Tue May 26 01:02:21 2026 -0700) on "macos_arm64"

If it still says command not found, the SDK's bin folder is not on the PATH. Add it (see the install step for your system), open another new terminal, and run dart --version again.

#Quick Revision

1. What does SDK stand for, and what does the Dart SDK contain?
2. What is the PATH, and what happens when dart is not on it?
3. Which command confirms that Dart is installed?
4. Which VS Code extension do you install for Dart, and who publishes it?
5. What does dart create do?
6. In which folder of a new project do you write your program?
7. What is the difference between dart run and dart run hello.dart?
8. Why might your output stay the same after you edit the code?

#Key Takeaways

• The Dart SDK is the toolbox; the dart command is how you use every tool in it.
• Install with Chocolatey or a .zip on Windows, Homebrew on macOS, and apt or a .zip on Linux. Flutter also includes Dart.
• command not found means the terminal cannot find dart — open a new terminal, then check your PATH.
• dart --version confirms the install; dart --help lists every tool.
• VS Code with the Dart extension (by Dart Code) is the editor for this course.
• dart create name builds a project; your code lives in bin/.
• dart run runs a project; dart run file.dart runs a single file.
• The working loop is edit, save, run, read the output.

#What's Next?

Lecture 03 — Your First Dart Program & Comments. Your tools are ready, and you have already run a few programs by copying them. Next we will write a program from an empty file and understand every part of it — main(), print(), statements, and semicolons — and learn how comments let you leave notes in your code that Dart ignores.