Getting Map Size

Part of the Fundamentals section of Coddy's Dart journey — lesson 60 of 94.

The length property of a map returns the number of key-value pairs it contains. This helps you know how many entries are in your map.

Create a map of student scores:

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

Get the size of the map using the length property:

int numberOfStudents = scores.length;
print('Number of students: $numberOfStudents');

After executing the above code, the output will be:

Number of students: 3

Challenge

Beginner

In this challenge, you'll practice getting the size (number of key-value pairs) of a Map using the length property.

The code below contains a Map called fruitPrices that stores different fruits and their prices. Your task is to find out how many fruits are in the map by using the length property and store it in the fruitCount variable.

Expected output:

Number of fruits in the store: 4

Cheat sheet

The length property of a map returns the number of key-value pairs it contains:

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

int numberOfStudents = scores.length;
print('Number of students: $numberOfStudents'); // Output: Number of students: 3

Try it yourself

void main() {
  // A map of fruits and their prices
  Map<String, double> fruitPrices = {
    'Apple': 1.99,
    'Banana': 0.99,
    'Orange': 1.49,
    'Mango': 2.49
  };
  
  // TODO: Get the number of fruits in the map using the length property
  // and store it in the fruitCount variable
  int fruitCount = 0;
  
  // This will display the result
  print('Number of fruits in the store: $fruitCount');
}