Kotlin Basics

Question 1

.
How do you define a simple printHello() function in Kotlin?

Answer 1

fun printHello() {
println(“Hello”)
}

Question 2

What are the basic mathematical operators in Kotlin?

Answer 2

+, -, *, /, %

Question 3

What are the increment and decrement operators in Kotlin?

nb// remeber pre and post

Answer 3

: ++ (increment), – (decrement)

pre = ++a . shows me exact value of a but if I print later it will increase

post =a++

Question 4

What is the syntax for calling numeric operator methods on numbers in Kotlin?

Answer 4

2.times(3) // Output: 6
3.5.plus(4) // Output: 7.5
2.4.div(2) // Output: 1.2

Question 5

What are the integer data types in Kotlin?

Answer 5

Long (64 bits)
Int (32 bits)
Short (8 bits)

Question 6

What is type casting in Kotlin? Provide an example of casting Int to Byte.

Answer 6

he process of converting an object from one data type to another,
val i: Int = 6
println(i.toByte()) // Output: 6

Question 7

How do you use underscores for long numbers in Kotlin?

Answer 7

val oneMillion = 1_000_000
val idNumber = 999_99_9999L

Question 8

How do you perform string concatenation in Kotlin using variable interpolation?

Answer 8

val numberOfDogs = 3
val numberOfCats = 2
“I have $numberOfDogs dogs and $numberOfCats cats”

Question 9

What is a string template in Kotlin? Provide an example.

Answer 9

allows embedding variables or expressions inside a string using the $ symbol

val i = 10
println(“i = $i”) // Output: i = 10

Question 10

Q: What are the mutable and immutable variables in Kotlin?

Answer 10

Mutable (can be changed): var, e.g., var count = 1
n
Immutable(cant change): val, e.g., val name = “Jennifer”

Question 11

How does an if/else statement work in Kotlin? Provide an example.

Answer 11

val numberOfCups = 30
val numberOfPlates = 10

if (numberOfCups > numberOfPlates) {
println(“Too many cups!”)
} else {
println(“Not enough cups!”)
}

Question 12

What is a when statement in Kotlin? Provide an example.

Answer 12

a conditional expression that acts like a switch-case, allowing multiple conditions to be checked in a concise and readable way.

when (results) {
0 -> println(“No results”)
in 1..39 -> println(“Got results!”)
else -> println(“That’s a lot of results!”)
}

Question 13

How do you declare and iterate over an array in Kotlin?

Answer 13

val pets = arrayOf(“dog”, “cat”, “canary”)
for (element in pets) {
print(element + “ “)
}
// Output: dog cat canary

Question 14

What is the purpose of the safe call operator (?) in Kotlin?

Answer 14

it indicates that a variable can be null. Example:

numberOfBooks = numberOfBooks?.dec() ?: 0

Question 15

What is the Elvis operator (?:) used for in Kotlin?

Answer 15

It’s used to provide a default value when a nullable variable is null:

numberOfBooks = numberOfBooks?.dec() ?: 0

Question 16

How do you create a for loop with a step size in Kotlin?

Answer 16

for (i in 1..10 step 2) {
println(i)
}
// Output: 1, 3, 5, 7, 9

Question 17

How do you use a for loop with indices in Kotlin?

Answer 17

val pets = arrayOf(“dog”, “cat”, “canary”)
for ((index, element) in pets.withIndex()) {
println(“Item at $index is $element”)
}

Question 18

How do you combine two arrays in Kotlin using a for loop?

Answer 18

val numbers1 = intArrayOf(1, 2, 3)
val numbers2 = intArrayOf(4, 5, 6)
val combined = numbers1 + numbers2
for (num in combined) {
println(num)
}
// Output: 1, 2, 3, 4, 5, 6

Question 19

How can you iterate over a list in Kotlin using a for loop?

Answer 19

val instruments = listOf(“guitar”, “drums”, “piano”)
for (instrument in instruments) {
println(instrument)
}

Question 20

What is the purpose of the repeat function in Kotlin?

Answer 20

It repeats a block of code a specified number of times. Example:

repeat(3) {
println(“Hello!”)
}
// Output: Hello! Hello! Hello!

Question 21

How does a do-while loop work in Kotlin?

Answer 21

var bicycles = 50
do {
bicycles–
} while (bicycles > 0)
println(“$bicycles bicycles left”)
// Output: 0 bicycles left