Accessing Values by Key

Part of the Fundamentals section of Coddy's Dart journey — lesson 58 of 94.

The square bracket notation allows you to access values in a map using their associated keys.

Create a map of student scores:

Map<String, int> scores = {
  'Alice': 95,
  'Bob': 85,
  'Charlie': 90
};

Access a value using its key:

int aliceScore = scores['Alice'];
print('Alice\'s score: $aliceScore');

After executing the above code, the output will be:

Alice's score: 95

You can also use variables as keys to look up values:

String student = 'Bob';
int bobScore = scores[student];
print('$student\'s score: $bobScore');

After executing the above code, the output will be:

Bob's score: 85

Challenge

Beginner

In this challenge, you'll practice accessing values from a map using keys. Maps in Dart store data as key-value pairs, and you can retrieve values by using their associated keys.

Complete the code below to access the score for the student named 'Bob' from the studentScores map and store it in the bobScore variable.

Expected output:

Bob's score is: 85

Cheat sheet

Use square bracket notation to access values in a map using their keys:

Map<String, int> scores = {
  'Alice': 95,
  'Bob': 85,
  'Charlie': 90
};

// Access value using key
int aliceScore = scores['Alice'];

// Use variables as keys
String student = 'Bob';
int bobScore = scores[student];

Try it yourself

void main() {
  // This map is already defined for you
  Map<String, int> studentScores = {
    'Alice': 95,
    'Bob': 85,
    'Charlie': 90
  };
  
  // TODO: Access Bob's score from the map and store it in the variable below
  int? bobScore = 0; // Replace this with the correct code
  
  // This will display Bob's score
  print("Bob's score is: $bobScore");
}