Comments and documentation markup in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a single-line comment in Swift.

Swift

[1] This is a comment

Drag options to blanks, or click blank then click option'

A/*

B#

C<!--

D//

Attempts:

3 left

💡 Hint

Common Mistakes

Using /* for single-line comments instead of //

Using # which is not a comment in Swift

In Swift, single-line comments start with //.

2fill in blank

medium

Complete the code to start a multi-line comment in Swift.

Swift

[1] This is a 
multi-line comment 
*/

Drag options to blanks, or click blank then click option'

A//

B/*

C#

D<!--

Attempts:

3 left

💡 Hint

Common Mistakes

Using // for multi-line comments

Using # which is not a comment in Swift

Multi-line comments in Swift start with /* and end with */.

3fill in blank

hard

Fix the error in the documentation comment syntax.

Swift

[1] This function adds two numbers.
func add(a: Int, b: Int) -> Int {
    return a + b
}

Drag options to blanks, or click blank then click option'

A/*

B//

C///

D/**

Attempts:

3 left

💡 Hint

Common Mistakes

Using // instead of /// for documentation comments

Using /* or /** which are for multi-line comments

In Swift, documentation comments use three slashes /// before the comment.

4fill in blank

hard

Fill both blanks to create a documentation comment with a parameter description.

Swift

[1] Adds two numbers.
[2] - Parameter a: The first number.

Drag options to blanks, or click blank then click option'

A///

B//

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using // instead of /// for documentation

Using * instead of - for parameter description

Documentation comments start with ///. Parameter descriptions use a dash - followed by the parameter name.

5fill in blank

hard

Fill all three blanks to complete the documentation comment with summary, parameter, and return description.

Swift

[1] Calculates the sum of two integers.
[2] - Parameter x: The first integer.
[3] - Returns: The sum of x and y.

Drag options to blanks, or click blank then click option'

A///

B-

D//

Attempts:

3 left

💡 Hint

Common Mistakes

Using // instead of /// for documentation lines

Missing dashes before parameter or return descriptions

Documentation comments lines start with ///. Use a dash - before parameter and return descriptions.

Practice

1. What is the main purpose of comments in Swift code?

easy

A. To create new variables

B. To make the code run faster

C. To explain the code for better understanding

D. To store user data

Solution

1. Step 1: Understand what comments do

   Comments are notes in the code that do not affect how the program runs but help explain what the code does.

2. Step 2: Identify the purpose of comments

   Comments make the code easier to read and understand for yourself and others who read the code later.

3. Final Answer:

   To explain the code for better understanding -> Option C

4. Quick Check:

   Comments explain code [OK]

Hint: Comments explain code, not run it or store data [OK]

Common Mistakes:

• Thinking comments speed up code
• Confusing comments with variables
• Using comments to store data

2. Which of the following is the correct syntax for a single-line comment in Swift?

easy

A. # This is a comment

B. /* This is a comment */

C.

D. // This is a comment

Solution

1. Step 1: Recall Swift comment syntax

   Swift uses // for single-line comments and /* */ for multi-line comments.

2. Step 2: Match the correct syntax

   // This is a comment uses // which is the correct single-line comment syntax in Swift.

3. Final Answer:

   // This is a comment -> Option D

4. Quick Check:

   Single-line comment = // [OK]

Hint: Single-line comments start with // in Swift [OK]

Common Mistakes:

• Using /* */ for single-line comments
• Using HTML style comments
• Using # which is not a comment in Swift

3. What will the following Swift code output?

/// Adds two numbers
func add(_ a: Int, _ b: Int) -> Int {
    return a + b
}
print(add(3, 4))

medium

A. 7

B. add(3, 4)

C. /// Adds two numbers

D. Error: Unexpected documentation comment

Solution

1. Step 1: Understand documentation comments effect

   The line starting with /// is a documentation comment and does not affect the code execution.

2. Step 2: Execute the function call

   The function add returns the sum of 3 and 4, which is 7, and print outputs it.

3. Final Answer:

   7 -> Option A

4. Quick Check:

   Documentation comment ignored, output = 7 [OK]

Hint: Documentation comments don't change output, only explain [OK]

Common Mistakes:

• Thinking documentation comments print text
• Expecting error from documentation comments
• Confusing comments with code

4. Identify the error in this Swift code snippet:

/* This is a multi-line comment
func greet() {
    print("Hello")
}
// Missing closing comment delimiter

medium

A. Using // inside multi-line comment is invalid

B. Missing closing */ for multi-line comment

C. Function greet() is not declared properly

D. print statement syntax error

Solution

1. Step 1: Check multi-line comment syntax

   Multi-line comments start with /* and must end with */ to close properly.

2. Step 2: Identify missing closing delimiter

   The code has /* but no closing */, so the comment never ends, causing a syntax error.

3. Final Answer:

   Missing closing */ for multi-line comment -> Option B

4. Quick Check:

   Multi-line comment must close with */ [OK]

Hint: Multi-line comments need /* and */ to open and close [OK]

Common Mistakes:

• Ignoring missing closing comment delimiter
• Thinking // can't be inside multi-line comments
• Assuming function syntax is wrong

5. You want to document a Swift function so that Xcode shows its description and parameters clearly. Which comment style should you use?

func multiply(_ x: Int, _ y: Int) -> Int {
    return x * y
}

hard

A. /// Multiplies two numbers
/// - Parameters:
/// - x: The first number
/// - y: The second number
/// - Returns: The product of x and y

B. /* Multiplies two numbers */

C. // This function multiplies two numbers

D.

Solution

1. Step 1: Understand documentation comment usage

   Documentation comments in Swift use /// and special markup to describe functions and parameters for tools like Xcode.

2. Step 2: Identify the detailed documentation style

   /// Multiplies two numbers /// - Parameters: /// - x: The first number /// - y: The second number /// - Returns: The product of x and y uses /// with - Parameters and - Returns tags, which is the correct way to document for Xcode's quick help.

3. Final Answer:

   /// Multiplies two numbers /// - Parameters: /// - x: The first number /// - y: The second number /// - Returns: The product of x and y -> Option A

4. Quick Check:

   Use /// with parameter tags for documentation [OK]

Hint: Use /// with - Parameters and - Returns for Xcode docs [OK]

Common Mistakes:

• Using single-line or multi-line comments without markup
• Using HTML style comments
• Not including parameter descriptions