String concatenation vs templates in Kotlin - Practice Questions

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of string concatenation vs template

What is the output of this Kotlin code snippet?

Kotlin

val name = "Anna"
val age = 30
val greeting = "Hello, " + name + ". You are " + age + " years old."
println(greeting)

A Hello, name. You are age years old.

B Hello, Anna. You are 30 years old.

C Hello, Anna. You are age years old.

D Hello, name. You are 30 years old.

💡 Hint

Look at how variables are combined with strings using + operator.

The + operator concatenates strings and variables converted to strings. Variables are replaced by their values.

❓ Predict Output

intermediate

Output of string template with expression

What will this Kotlin code print?

Kotlin

val x = 5
val y = 10
println("Sum of $x and $y is ${x + y}")

A Sum of 5 and 10 is 15

B Sum of x and y is x + y

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

D Sum of 5 and 10 is x + y

💡 Hint

Remember that expressions inside ${} are evaluated.

The $x and $y insert variable values. The expression ${x + y} calculates the sum 15.

🔧 Debug

advanced

Identify the error in string concatenation

What error does this Kotlin code produce?

Kotlin

val name = "Bob"
val message = "Hello, " + name + ". " + "!"
println(message)

A SyntaxError: Unexpected token '.'

B TypeError: Cannot concatenate String and Char

C RuntimeException: Null pointer

D No error, prints: Hello, Bob.!

💡 Hint

Check the placement of the dot operator in concatenation.

The dot before the string literal is invalid syntax in Kotlin concatenation.

❓ Predict Output

advanced

Output of mixed string concatenation and template

What is the output of this Kotlin code?

Kotlin

val a = 3
val b = 4
val result = "Result: " + "$a + $b = " + (a + b)
println(result)

A Result: 3 + 4 = 7

B Result: $a + $b = a + b

C Result: $a + $b = 7

D Result: 3 + 4 = a + b

💡 Hint

Notice the quotes around $a and $b inside concatenation.

The string "$a + $b = " is literal text with dollar signs, not variables. Only (a + b) is evaluated.

🧠 Conceptual

expert

Why prefer string templates over concatenation?

Which is the best reason to prefer Kotlin string templates over string concatenation?

A Templates allow using variables without declaring them first.

B Templates run faster because they use less memory than concatenation.

C Concatenation is deprecated and will be removed in future Kotlin versions.

D Templates improve readability and reduce errors by embedding variables directly.

💡 Hint

Think about code clarity and ease of writing.

String templates make code easier to read and write by embedding variables and expressions directly inside strings.