Comments and documentation markup in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Swift documentation comment usage

What will be the output when this Swift code is run?

Swift

/// Returns the sum of two integers.
/// - Parameters:
///   - a: The first integer
///   - b: The second integer
/// - Returns: The sum of a and b
func add(_ a: Int, _ b: Int) -> Int {
    return a + b
}

print(add(3, 4))

A Compilation error due to comments

B Returns the sum of two integers.

C 3 4

D 7

💡 Hint

Documentation comments do not affect runtime output.

The triple slash comments (///) are used for documentation and do not affect the program execution. The function adds two numbers and prints the result.

❓ Predict Output

intermediate

Effect of nested multiline comments in Swift

What will be the output of this Swift code snippet?

Swift

/* Outer comment start
/* Inner comment */
Outer comment end */
print("Hello")

A Hello

B Compilation error due to nested comments

C /* Inner comment */ Hello

D No output, program crashes

💡 Hint

Swift supports nested multiline comments.

Swift allows nested multiline comments, so the entire comment block is ignored and the print statement runs normally.

❓ Predict Output

advanced

Output of code with single-line and multiline comments

What is printed when this Swift code runs?

Swift

// This is a single-line comment
let x = 5 /* This is a
multiline comment */
print(x)

A Compilation error due to comment placement

B 5

C

let x = 5
5

D 0

💡 Hint

Comments do not affect variable values.

Comments are ignored by the compiler. The variable x is assigned 5 and printed.

🧠 Conceptual

advanced

Purpose of documentation markup in Swift

Which option best describes the purpose of documentation markup comments (///) in Swift?

A They are used to disable code execution temporarily.

B They cause the compiler to optimize the code better.

C They generate documentation and help tools show info about code elements.

D They convert comments into runtime print statements.

💡 Hint

Think about how IDEs show help for functions.

Documentation comments provide structured info that tools use to generate docs and show quick help, but do not affect code execution.

🔧 Debug

expert

Identify the error caused by comment misuse

What error will this Swift code produce?

Swift

/* Start comment
// Single line comment inside
print("Hello")
/* Nested comment start
print("World")
*/
End comment */

A No error, prints nothing

B Prints Hello and World

C Syntax error: unterminated comment

D Prints Hello only

💡 Hint

Check if all multiline comments are properly closed.

Swift allows nesting of multiline comments. The outer comment properly closes at the final */. The entire code is commented out, so it compiles with no error and produces no output.