String interpolation in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of simple string interpolation

What is the output of this Swift code?

Swift

let name = "Alice"
let age = 30
print("My name is \(name) and I am \(age) years old.")

A My name is Alice and I am 30 years old.

B My name is \(name) and I am \(age) years old.

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

D My name is Alice and I am age years old.

💡 Hint

Look at how variables are inserted inside the string using \(variable).

Swift replaces \(variable) with the value of the variable inside the string.

❓ Predict Output

intermediate

String interpolation with expressions

What will this Swift code print?

Swift

let x = 5
let y = 3
print("Sum: \(x + y), Product: \(x * y)")

A Sum: x + y, Product: x * y

B Sum: 8, Product: x * y

C Sum: 53, Product: 15

D Sum: 8, Product: 15

💡 Hint

Inside \( ), Swift evaluates the expression before inserting it.

The expressions x + y and x * y are calculated and their results inserted.

🔧 Debug

advanced

Identify the error in string interpolation

What error does this Swift code produce?

Swift

let celsius = 22
print("Current temperature is \celsius degrees.")

A Prints: Current temperature is temperature degrees.

B Prints: Current temperature is \temperature degrees.

C SyntaxError: Missing parentheses around variable in string interpolation

D RuntimeError: Variable temperature not found

💡 Hint

Check how variables are inserted inside strings in Swift.

Swift requires variables inside string interpolation to be inside parentheses: \(variable).

❓ Predict Output

advanced

String interpolation with multiline strings

What is the output of this Swift code?

Swift

let name = "Bob"
let score = 95
let message = """Hello, \(name)!\nYour score is \(score).\n"""
print(message)

A

Hello, Bob!
Your score is 95.

B

Hello, \(name)!
Your score is \(score).

C Hello, Bob! Your score is 95.

D

Hello, name!
Your score is score.

💡 Hint

Multiline strings keep line breaks and support interpolation the same way.

The multiline string inserts variable values and preserves line breaks.

🧠 Conceptual

expert

Effect of using backslash without parentheses in interpolation

What happens if you write this Swift code? let count = 10 print("Count is \count")

A Prints: Count is \count

B Compiler error due to missing parentheses in string interpolation

C Prints: Count is count

D Prints: Count is 10

💡 Hint

Swift requires parentheses around variables in string interpolation.

Without parentheses, the backslash is not recognized as interpolation and causes a syntax error.