Your First Dart Program

Every Dart program starts in a function called main. Create a file called hello.dart:

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

Run it from the folder that contains it:

dart run hello.dart

Expected output

Hello, world!

Line by line:

• void main() declares the main function — where the program starts. void means it doesn't return a value.
• The curly braces { } hold the function's code.
• print(...) writes a value to the screen, followed by a new line.
• 'Hello, world!' is a string — text in quotes. Dart accepts single or double quotes; single quotes are the usual style.
• Each statement ends with a semicolon ;.

A slightly longer program runs line by line, top to bottom:

void main() {
  print('Hello, world!');
  print('I am learning Dart.');
  print(2 + 3);
}

Hello, world!
I am learning Dart.
5

Common mistakes

• Forgetting a semicolon. Dart reports Error: Expected ';' after this. and points at the spot.
• Writing Print with a capital P. Dart is case-sensitive.

Practice

Write a program that prints your name on one line and your favorite food on the next.

void main() {
  print('Ada');
  print('Pizza');
}