Tutorial: Dartboard & Language Basics

About the code

This example illustrates some basic Dart features and conventions:

Top-level main() function

Having a main() function with no surrounding class lets Dart know where to start executing your code.

Variable declared with var

Whenever you create a variable in a Dart program, you must use the var keyword, the final keyword, or a type name to declare that variable.

Output with print()

Dart's print() function sends text to the console.

String literals

You can use either single or double quotes to mark strings: 'World' and "World" are equally valid.

String interpolation with ${expression}

Dart lets you embed expressions within string literals. If the expression is just a variable, as it is in this example, then you can omit the curly braces ({}). Another alternative for building strings is the plus operator (+). For example, the following three statements are equivalent:

print('Hello, ${name}!');
print('Hello, $name!');
print('Hello, ' + name + '!');

Try this

Edit the code and click the Run button (the button at the upper left of Dartboard) to compile and run the new code.

Some changes to try:

• Change 'World' to some other string—maybe 'Mondo' or "you".
• Change ${name} to $name.
• Embed an arithmetic expression in the output string. For example:

  var age = 21;
  print("Happy birthday, $name, you're ${++age} today.");
  

Tips for using Dartboard

• Dartboard indicates warnings with yellow flags and errors with red flags. Mouse over the flag to see a description of the problem.
• When you edit the code originally displayed by Dartboard, a Reload button appears at the top of the Dartboard. Click it to go back to the original code.
• The usual keyboard shortcuts should work in Dartboard. For example, in Google Chrome on a Mac , Command-Z undoes your last change, and Shift-Command-Z re-applies it.