Required Named Parameters

Part of the Fundamentals section of Coddy's Dart journey — lesson 74 of 94.

The required keyword forces named parameters to be provided when calling a function. Without it, named parameters are optional by default.

Create a function with required named parameters:

void createUser({required String name, required int age}) {
  print('User created: $name, $age years old');
}

Call the function with all required parameters:

void main() {
  createUser(name: 'Alex', age: 30);
}

After executing the above code, the output will be:

User created: Alex, 30 years old

If you try to omit a required parameter, Dart will show an error:

// This would cause an error:
// createUser(name: 'Alex'); // Missing required parameter 'age'

Challenge

Beginner

In this challenge, you'll practice using the required keyword with named parameters in Dart. The required keyword ensures that a named parameter must be provided when calling a function.

Complete the createUserProfile function by adding the required keyword to make both the name and age parameters required.

Try it yourself

void main() {
  // This function call is already set up for you
  String profile = createUserProfile(name: 'Alice', age: 30);
  print(profile);
  
  // Uncomment this line to see what happens when required parameters are missing
  // String invalidProfile = createUserProfile(name: 'Bob');
}

// TODO: Add the 'required' keyword to make both parameters required
String createUserProfile({String name, int age}) {
  return 'User Profile: $name, $age years old';
}