Single-expression functions in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a single-expression function that returns the square of a number.

Kotlin

fun square(x: Int): Int = [1]

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

Ax * x

Breturn x * x

Cx + x

Dprintln(x)

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'return' keyword inside a single-expression function.

Using curly braces instead of '=' for single-expression functions.

The single-expression function uses the '=' sign followed by the expression. Here, x * x correctly returns the square.

2fill in blank

medium

Complete the code to define a single-expression function that returns the length of a string.

Kotlin

fun lengthOf(str: String): Int = [1]

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

Astr.length()

Bstr.length

Cstr.size

Dstr.count()

Attempts:

3 left

💡 Hint

Common Mistakes

Using length() with parentheses which is invalid in Kotlin.

Using size which is for collections, not strings.

In Kotlin, the length of a string is accessed using the length property without parentheses.

3fill in blank

hard

Fix the error in the single-expression function that returns true if a number is even.

Kotlin

fun isEven(num: Int): Boolean = num [1] 2 == 0

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

A%

B/

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using division / instead of modulo %.

Using multiplication or addition operators which don't check evenness.

The modulo operator % gives the remainder. If num % 2 == 0, the number is even.

4fill in blank

hard

Complete the code to create a single-expression function that returns the last character of a string.

Kotlin

fun lastChar(str: String): Char = str[1]

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

A[

B]

Cstr.length - 1

DlastIndex

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets for indexing.

Omitting the str. prefix before length.

To get the last character, use the indexing operator [] with str.length - 1 which gives the last valid index.

5fill in blank

hard

Fill all three blanks to define a single-expression function that returns a greeting message with the user's name.

Kotlin

fun greet(name: String): String = "Hello, [1]!".[2]() + [3]

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

A$name

Buppercase

C" Have a nice day."

DtoUpperCase

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase() which is Kotlin 1.5+ but not always available.

Forgetting to add parentheses after the uppercase function.

Not adding the extra greeting string at the end.

The function inserts the name inside the greeting string, converts it to uppercase with toUpperCase(), and adds a friendly message.