Variables and type inference in Flutter - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable with type inference holding the number 10.

Flutter

var number = [1];

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

A10.0

B"10"

Cten

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the number inside quotes makes it a string, not a number.

Using a decimal number when an integer is expected.

The keyword var lets Dart infer the type from the assigned value. Here, 10 is an integer, so number becomes an int.

2fill in blank

medium

Complete the code to declare a variable with type inference holding the text 'Hello'.

Flutter

var greeting = [1];

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

AHello

B"Hello"

C'Hello

Dhello

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around text makes Dart think it's a variable name.

Using mismatched or missing quotes causes errors.

Text values must be inside quotes. Double or single quotes work, but here double quotes are correct and complete.

3fill in blank

hard

Fix the error in the code by completing the variable declaration with type inference for a decimal number.

Flutter

var price = [1];

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

A100.5

B"100.5"

C100

Done hundred point five

Attempts:

3 left

💡 Hint

Common Mistakes

Putting decimal numbers inside quotes makes them strings.

Using words instead of numeric literals causes errors.

Decimal numbers need to be written as numeric literals with a dot, without quotes, so Dart infers a double type.

4fill in blank

hard

Fill both blanks to declare a variable with explicit type and assign it a boolean value.

Flutter

[1] isActive = [2];

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

Abool

Btrue

Cfalse

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Using var when explicit type is asked.

Putting boolean values inside quotes makes them strings.

Explicitly declaring the type bool tells Dart this variable holds true/false values. Assigning true sets it to true.

5fill in blank

hard

Fill both blanks to declare a variable with type inference, assign a list of integers, and access the first element.

Flutter

var numbers = [1];
int first = numbers[2];
print(first);;

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

A[1, 2, 3]

B[0]

C;

D[1]

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets for lists or indexing.

Forgetting the semicolon at the end of statements.

The list [1, 2, 3] holds integers. Indexing uses square brackets starting at 0, so numbers[0] gets the first element. Statements end with a semicolon ;.