Repeat function for simple repetition in Kotlin - Mini Project: Build & Apply

Repeat function for simple repetition

📖 Scenario: You want to greet your friends multiple times to make them feel special. Instead of writing the greeting many times, you will use Kotlin's repeat function to say hello several times easily.

🎯 Goal: Build a Kotlin program that uses the repeat function to print a greeting message multiple times.

📋 What You'll Learn

Create a variable called times with the value 3.

Use the repeat function with the variable times to print "Hello, friend!" exactly 3 times.

💡 Why This Matters

🌍 Real World

Repeating actions many times is common in apps, like showing notifications or processing lists.

💼 Career

Understanding how to repeat tasks efficiently helps you write cleaner and shorter code in real projects.

1

Create the times variable

Create a variable called times and set it to 3.

Kotlin

# Create a variable called times and set it to 3
// Your code here

Hint

Use val times = 3 to create the variable.

2

Use repeat to print greetings

Use the repeat function with the variable times to print "Hello, friend!" exactly 3 times.

Kotlin

val times = 3
// Use repeat(times) to print "Hello, friend!" 3 times
// Your code here

Hint

Use repeat(times) { println("Hello, friend!") } to print the message multiple times.

3

Add a message count inside the repeat

Modify the repeat block to print the message number before each greeting, like "Greeting 1: Hello, friend!".

Kotlin

val times = 3
repeat(times) {
    // Print message number and greeting
    // Your code here
}

Hint

Use repeat(times) { count -> println("Greeting ${count + 1}: Hello, friend!") } to include the count.

4

Print the final greetings

Run the program to print the greetings with their numbers using println.

Kotlin

val times = 3
repeat(times) { count ->
    println("Greeting ${count + 1}: Hello, friend!")
}
// Print the greetings above
// Your code here

Hint

Just run the program to see the greetings printed.

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