Repeat function for simple repetition in Kotlin

Introduction

The repeat function helps you run the same code multiple times easily without writing a loop manually.

When you want to print a message several times.

When you need to perform a task repeatedly, like retrying a connection.

When you want to fill a list or array with repeated values.

When you want to run a block of code a fixed number of times for testing.

Syntax

Kotlin

repeat(times: Int) {
    // code to repeat
}

times is how many times the code inside will run.

The code inside the curly braces runs each time, from 0 up to times-1.

Examples

This prints "Hello" three times.

Kotlin

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

This prints the count from 0 to 4 using the index variable.

Kotlin

repeat(5) { index ->
    println("Count: $index")
}

Sample Program

This program prints the phrase "Kotlin is fun!" four times using repeat.

Kotlin

fun main() {
    repeat(4) {
        println("Kotlin is fun!")
    }
}

Important Notes

You can use the optional index parameter inside the repeat block to know which repetition you are on.

Repeat is a simple and clean way to avoid writing loops when you know the exact number of repetitions.

Summary

The repeat function runs code a set number of times.

It makes repeating tasks easy and clean without manual loops.

You can access the current repetition count with an index if needed.

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