Dart programming language overview in Flutter - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable that cannot be changed.

Flutter

final [1] = 10;

Drag options to blanks, or click blank then click option'

Avar

Bconst

Ccount

Dlet

Attempts:

3 left

💡 Hint

Common Mistakes

Using a keyword like 'var' as a variable name.

Leaving the variable name blank.

The keyword final declares a variable that cannot be changed after it is set. You need to provide a variable name, like count.

2fill in blank

medium

Complete the code to define a function that returns a greeting string.

Flutter

String greet() {
  return [1];
}

Drag options to blanks, or click blank then click option'

A'Hello World'

BHello World

C"Hello World"

Dgreeting

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the string.

Using a variable name that is not defined.

The function returns a string literal. In Dart, string literals can be in single quotes '...' or double quotes "...". Here, single quotes are used.

3fill in blank

hard

Fix the error in the code to create a list of integers.

Flutter

List<int> numbers = [1];

Drag options to blanks, or click blank then click option'

A<1, 2, 3, 4>

B(1, 2, 3, 4)

C{1, 2, 3, 4}

D[1, 2, 3, 4]

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets.

Using curly braces which create a set.

In Dart, lists are created using square brackets []. Parentheses () are for tuples (not in Dart), curly braces {} are for sets or maps, and angle brackets <> are for generics.

4fill in blank

hard

Fill both blanks to create a map with string keys and integer values.

Flutter

Map<String, int> ages = [1];
ages['Alice'] = [2];

Drag options to blanks, or click blank then click option'

A{'Bob': 30}

B25

C40

D['Bob', 30]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a list instead of a map.

Assigning a string instead of an integer value.

The map is created with curly braces and key-value pairs. To add or update a value, use the key in brackets and assign an integer.

5fill in blank

hard

Fill all three blanks to create a conditional that prints a message if a number is positive.

Flutter

int number = 5;
if (number [1] 0) {
  print([2]);
} else {
  print([3]);
}

Drag options to blanks, or click blank then click option'

A>

B'Positive'

C'Not positive'

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong comparison operator.

Forgetting quotes around the strings in print.

The condition checks if the number is greater than zero. If true, it prints 'Positive', otherwise 'Not positive'.