Repeat function for simple repetition in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to repeat the print statement 3 times using the repeat function.

Kotlin

repeat([1]) {
    println("Hello")
}

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

A3

B5

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 will not print anything.

Using 1 will print only once, not three times.

The repeat function takes the number of times to repeat as its argument. Here, 3 repeats the print statement 3 times.

2fill in blank

medium

Complete the code to print the numbers 0 to 4 using repeat and the loop index.

Kotlin

repeat(5) { [1] ->
    println([1])
}

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

Anum

Bcount

Cindex

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name not declared in the lambda.

Forgetting to use the lambda parameter to print the index.

The lambda parameter in repeat is commonly named i to represent the current index from 0 up to one less than the repeat count.

3fill in blank

hard

Fix the error in the code to correctly repeat printing "Hi" 4 times.

Kotlin

repeat([1]) {
    println("Hi")
}

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

Afour

B4

C"4"

D4L

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string like "4" causes a type error.

Using a variable name that is not defined.

The repeat function expects an integer argument without quotes. Using 4 (an Int) works correctly.

4fill in blank

hard

Fill both blanks to create a map of numbers to their squares using repeat.

Kotlin

val squares = mutableMapOf<Int, Int>()
repeat([1]) { [2] ->
    squares[[2]] = [2] * [2]
}

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

A5

Bi

Cindex

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using a number too large or too small for the repeat count.

Using a variable name not matching the lambda parameter.

We repeat 5 times and use i as the index variable to fill the map with numbers and their squares.

5fill in blank

hard

Fill all three blanks to create a list of even numbers using repeat and an if condition.

Kotlin

val evens = mutableListOf<Int>()
repeat([1]) { [2] ->
    if ([2] % 2 == 0) {
        evens.add([2])
    }
}

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

A10

Bi

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for the loop index in condition and add.

Repeating fewer times than needed to get all even numbers.

We repeat 10 times, use i as the index, and add i to the list if it is even.

Practice

1. What does the Kotlin repeat function do?

easy

A. Defines a loop that runs until a condition is false

B. Repeats a string multiple times

C. Runs a block of code a specified number of times

D. Creates a list with repeated elements

Solution

1. Step 1: Understand the purpose of repeat

   The repeat function is designed to run a block of code a fixed number of times.

2. Step 2: Compare with other options

   Options B and C describe string or list repetition, which are different functions. Defines a loop that runs until a condition is false describes a conditional loop, not repeat.

3. Final Answer:

   Runs a block of code a specified number of times -> Option C

4. Quick Check:

   repeat = run code N times [OK]

Hint: Remember: repeat runs code block N times [OK]

Common Mistakes:

• Confusing repeat with string repetition
• Thinking repeat creates collections
• Mixing repeat with while or for loops

2. Which of the following is the correct syntax to repeat a print statement 3 times in Kotlin?

easy

A. repeat 3 { println("Hello") }

B. repeat(3) { println("Hello") }

C. repeat(3); println("Hello")

D. repeat {3} println("Hello")

Solution

1. Step 1: Check the function call syntax

   The repeat function requires parentheses around the number of repetitions and a lambda block with curly braces.

2. Step 2: Validate each option

   repeat(3) { println("Hello") } correctly uses repeat(3) { ... }. Options B, C, and D have syntax errors or misplaced braces.

3. Final Answer:

   repeat(3) { println("Hello") } -> Option B

4. Quick Check:

   repeat(number) { code } syntax [OK]

Hint: Use parentheses for count and braces for code block [OK]

Common Mistakes:

• Omitting parentheses around the count
• Using semicolon instead of braces
• Placing braces incorrectly

3. What will be the output of this Kotlin code?

repeat(4) { i -> println(i * 2) }

medium

A. 0 1 2 3

B. 2 4 6 8

C. 1 2 3 4

D. 0 2 4 6

Solution

1. Step 1: Understand the index parameter

   The lambda receives i from 0 to 3 (4 times). Each iteration prints i * 2.

2. Step 2: Calculate each output line

   For i=0: 0*2=0, i=1: 2, i=2: 4, i=3: 6. So output lines are 0, 2, 4, 6.

3. Final Answer:

   0 2 4 6 -> Option D

4. Quick Check:

   repeat with index * 2 = 0 2 4 6 [OK]

Hint: Index starts at 0 in repeat lambda [OK]

Common Mistakes:

• Starting index at 1 instead of 0
• Forgetting to multiply by 2
• Confusing output with index values

4. Identify the error in this Kotlin code:

repeat(3) 
 println("Hi")

medium

A. Missing curly braces for the code block

B. repeat cannot be used with println

C. repeat requires a semicolon after the number

D. The number 3 should be a string

Solution

1. Step 1: Check the syntax of repeat

   The repeat function expects a lambda block enclosed in curly braces after the count.

2. Step 2: Identify the missing braces

   The code has no braces around println("Hi"), so it is a syntax error.

3. Final Answer:

   Missing curly braces for the code block -> Option A

4. Quick Check:

   repeat needs braces { } for code [OK]

Hint: Always use braces { } after repeat(count) [OK]

Common Mistakes:

• Omitting braces for single statement
• Adding semicolon after number
• Passing number as string

5. How can you use repeat to create a list of squares of numbers from 0 to 4 in Kotlin?

hard

A. val squares = mutableListOf<Int>(); repeat(5) { squares.add(it * it) }

B. val squares = repeat(5) { it * it }

C. val squares = List(5) { repeat(it * it) }

D. val squares = repeat(5) { println(it * it) }

Solution

1. Step 1: Understand repeat usage for list building

   The repeat function runs code multiple times but does not return a list itself.

2. Step 2: Check each option's approach

   val squares = mutableListOf<Int>(); repeat(5) { squares.add(it * it) } creates a mutable list and adds squares inside repeat, which works. val squares = repeat(5) { it * it } tries to assign repeat's result directly, which is Unit (no list). val squares = List(5) { repeat(it * it) } misuses List and repeat. val squares = repeat(5) { println(it * it) } only prints values, no list created.

3. Final Answer:

   val squares = mutableListOf<Int>(); repeat(5) { squares.add(it * it) } -> Option A

4. Quick Check:

   repeat + add to list = correct list [OK]

Hint: Use repeat to add items to a mutable list [OK]

Common Mistakes:

• Expecting repeat to return a list
• Using repeat inside List constructor incorrectly
• Only printing values without storing