Comments and documentation syntax in Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of code with single-line and multi-line comments

What is the output of this Kotlin code snippet?

Kotlin

fun main() {
    // This is a single-line comment
    val x = 5
    /* This is a
       multi-line comment */
    val y = 10
    println(x + y) // prints sum
}

A 15

B 510

C Compilation error due to comments

D 5 + 10

💡 Hint

Remember that comments do not affect the code execution.

Comments are ignored by the compiler. The code adds x and y (5 + 10) and prints 15.

❓ Predict Output

intermediate

Output of Kotlin code with KDoc documentation comments

What will be printed when running this Kotlin code?

Kotlin

/**
 * Returns the sum of two integers.
 * @param a first integer
 * @param b second integer
 * @return sum of a and b
 */
fun sum(a: Int, b: Int): Int {
    return a + b
}

fun main() {
    println(sum(3, 4))
}

A Compilation error due to KDoc

B sum of a and b

C 3 4

D 7

💡 Hint

Documentation comments do not affect runtime output.

KDoc comments are for documentation only and do not affect the program output. The sum function returns 7.

❓ Predict Output

advanced

Effect of nested comments in Kotlin

What happens when you try to compile and run this Kotlin code?

Kotlin

fun main() {
    /* Start of comment
    /* Nested comment */
    End of comment */
    println("Hello")
}

A Compilation error due to nested comments

B Prints Hello

C Prints /* Nested comment */

D Runtime error

💡 Hint

Kotlin does not support nested block comments.

Kotlin block comments cannot be nested. The compiler will raise an error.

❓ Predict Output

advanced

Output of code with commented out code lines

What is the output of this Kotlin program?

Kotlin

fun main() {
    val a = 10
    // val b = 20
    val c = 30
    // println(a + b)
    println(a + c)
}

A Compilation error due to b being undefined

B 40

C 30

D 10

💡 Hint

Commented out code does not run or affect variables.

The variable b and the print statement using b are commented out, so only a + c (10 + 30) is printed.

🧠 Conceptual

expert

Identifying correct KDoc usage for function documentation

Which of the following KDoc comments correctly documents a Kotlin function that returns the maximum of two integers?

A

/*
 * Returns max of two integers
 * @param a first integer
 * @param b second integer
 * @return larger integer
 */

B

// Returns max of a and b
// a: first integer
// b: second integer
// returns larger integer

C

/**
 * Returns the maximum of two integers.
 * @param a first integer
 * @param b second integer
 * @return the larger integer
 */

D

/**
 * Returns max of two integers
 * @param a first integer
 * @param b second integer
 * @param c unused parameter
 * @return larger integer
 */

💡 Hint

KDoc uses /** ... */ with @param and @return tags.

Option C uses proper KDoc syntax with correct tags. Option C uses single-line comments, not KDoc. Option C uses block comments but not KDoc style. Option C has an incorrect @param tag for a non-existent parameter.