Constant Variables

Part of the Fundamentals section of Coddy's Dart journey. Lesson 12 of 94.

The const keyword creates variables with fixed values. When using const, values must be known when writing your code.

void main() {
  const String language = 'Dart';
  print(language);
}

Type inference works with const:

void main() {
  const language = 'Dart';      // String
  const version = 2;            // int
  const isStable = true;        // bool
  const rating = 4.9;           // double
  
  print(language);  // Outputs: Dart
  print(version);   // Outputs: 2
  print(isStable);  // Outputs: true
  print(rating);    // Outputs: 4.9
}

Challenge

Beginner

Create a Dart program that uses constant variables to store information about a fictional planet:

Declare a const String variable named planetName with the value "Mars"
Declare a const int variable named numberOfMoons with the value 2
Declare a const double variable named distanceFromSun with the value 227.9 (in million km)
Declare a const bool variable named hasRings with the value false
Print each variable with a descriptive label exactly as shown in the expected output below:

Planet Name: Mars
Number of Moons: 2
Distance from Sun: 227.9 million km
Has Rings: false

Your output must match this exact format.

Try it yourself

void main() {
  // Declare your const variables here
  const String planetName = ?;
  const int numberOfMoons = ?;
  const double distanceFromSun = ?;
  const bool hasRings = ?;
  
  // Print the variables with labels
  print("Planet Name: $planetName");
  print("Number of Moons: $numberOfMoons");
  print("Distance from Sun: $distanceFromSun million km");
  print("Has Rings: $hasRings");
}