String templates and interpolation in Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of simple string template

What is the output of this Kotlin code using string templates?

Kotlin

val name = "Anna"
val age = 25
println("My name is $name and I am $age years old.")

A My name is Anna and I am 25 years old.

B My name is $name and I am $age years old.

C My name is Anna and I am age years old.

D My name is name and I am 25 years old.

💡 Hint

Remember that $variable inside a string replaces with the variable's value.

In Kotlin, $name and $age inside a string are replaced by their values, so the output shows the actual values.

❓ Predict Output

intermediate

Using expressions inside string templates

What will this Kotlin code print?

Kotlin

val x = 5
val y = 3
println("Sum of $x and $y is ${x + y}")

A Sum of 5 and 3 is 53

B Sum of x and y is x + y

C Sum of 5 and 3 is ${x + y}

D Sum of 5 and 3 is 8

💡 Hint

Expressions inside ${} are evaluated before printing.

The expression ${x + y} calculates 5 + 3 and inserts 8 into the string.

🔧 Debug

advanced

Identify the error in string interpolation

What error does this Kotlin code produce?

Kotlin

val count = 10
println("You have $count items in your cart")
println("Next item price is $price")

A Syntax error: missing curly braces

B No error, prints both lines correctly

C Unresolved reference: price

D Type mismatch error

💡 Hint

Check if all variables used inside strings are declared.

Variable 'price' is not declared anywhere, so Kotlin reports 'Unresolved reference: price'.

❓ Predict Output

advanced

Complex string interpolation with multiline string

What is the output of this Kotlin code?

Kotlin

val user = "Bob"
val score = 42
val message = """
Hello, $user!
Your score is ${score * 2}.
Good luck!
"""
println(message.trim())

A

Hello, $user!
Your score is ${score * 2}.
Good luck!

B

Hello, Bob!
Your score is 84.
Good luck!

C

Hello, Bob!
Your score is score * 2.
Good luck!

D Hello, Bob! Your score is 42. Good luck!

💡 Hint

Multiline strings keep line breaks and expressions inside ${} are evaluated.

The multiline string preserves line breaks and evaluates ${score * 2} as 84.

🧠 Conceptual

expert

Understanding string template evaluation order

Consider this Kotlin code snippet: val a = 3 val b = 4 println("Result: ${a + b}") println("Result: $a + $b") What will be the output?

A

Result: 7
Result: 3 + 4

B

Result: 7
Result: 7

C

Result: 7
Result: $a + $b

D

Result: a + b
Result: 3 + 4

💡 Hint

Expressions inside ${} are evaluated, but $variable just inserts the variable's value.

The first println evaluates ${a + b} to 7. The second prints the values of a and b separately with a plus sign in between.