Semicolons are optional behavior in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Swift code with semicolons?

Consider this Swift code snippet where semicolons are used at the end of each statement. What will be printed when this code runs?

Swift

let a = 5;
let b = 10;
print(a + b);

A 15

B 510

C Syntax Error

D 5 + 10

💡 Hint

Semicolons separate statements but do not change how expressions are evaluated.

Semicolons in Swift are optional and only separate statements. The code adds 5 and 10, printing 15.

❓ Predict Output

intermediate

What happens if you omit semicolons in Swift?

Look at this Swift code without semicolons. What will be the output?

Swift

let x = 3
let y = 7
print(x * y)

A 37

B 21

C Syntax Error

D x * y

💡 Hint

Swift allows omitting semicolons if statements are on separate lines.

Swift does not require semicolons if each statement is on its own line. The code multiplies 3 by 7 and prints 21.

❓ Predict Output

advanced

What is the output of this Swift code with multiple statements on one line?

This Swift code puts two statements on the same line separated by a semicolon. What will it print?

Swift

let name = "Swift"; print("Hello, \(name)!")

A Hello, Swift!

B Hello, name!

C Syntax Error

D Hello, \(name)!

💡 Hint

Semicolons allow multiple statements on one line.

The semicolon separates two statements on the same line. The print statement uses string interpolation to print Hello, Swift!

❓ Predict Output

advanced

What error does this Swift code produce without semicolons on the same line?

What error will this Swift code cause when run?

Swift

let a = 1 let b = 2
print(a + b)

A Runtime Error

B 3

C Syntax Error: Expected ';' after expression

D No output

💡 Hint

Swift requires semicolons to separate multiple statements on the same line.

When two statements are on the same line without a semicolon, Swift raises a syntax error expecting a semicolon.

🧠 Conceptual

expert

How do semicolons affect Swift code readability and style?

Which statement best describes the role of semicolons in Swift code style and readability?

A Semicolons are deprecated and cause warnings if used.

B Semicolons must be used only in loops and conditionals for clarity.

C Semicolons are mandatory and improve readability by clearly ending statements.

D Semicolons are optional and usually omitted to keep code clean and readable.

💡 Hint

Think about common Swift style guides and how code is usually written.

Swift allows semicolons but style guides recommend omitting them to keep code clean and easy to read.

Practice

1. In Swift, when are semicolons required at the end of statements?

easy

A. Never, semicolons are not used in Swift

B. Always at the end of every statement

C. Only after function declarations

D. Only when multiple statements are on the same line

Solution

1. Step 1: Understand Swift statement endings

   Swift allows statements to end without semicolons if each is on its own line.

2. Step 2: Identify when semicolons are necessary

   Semicolons are needed only to separate multiple statements on the same line.

3. Final Answer:

   Only when multiple statements are on the same line -> Option D

4. Quick Check:

   Semicolons required = multiple statements on one line [OK]

Hint: Semicolons separate statements on the same line only [OK]

Common Mistakes:

• Thinking semicolons are always required
• Believing semicolons are needed after every statement
• Assuming semicolons are never used

2. Which of the following Swift code snippets is syntactically correct?

easy

A. let a = 5; let b = 10;

B. let a = 5 let b = 10;

C. let a = 5; let b = '10'

D. let a = 5 let b = 10

Solution

1. Step 1: Check semicolon usage on same line

   When two statements are on the same line, they must be separated by a semicolon.

2. Step 2: Verify each option

   let a = 5; let b = 10; correctly uses a semicolon between two statements on the same line.

3. Final Answer:

   let a = 5; let b = 10; -> Option A

4. Quick Check:

   Multiple statements same line = semicolon needed [OK]

Hint: Use semicolons only to separate statements on the same line [OK]

Common Mistakes:

• Omitting semicolon between statements on the same line
• Adding semicolons unnecessarily at line ends
• Confusing semicolon placement with other languages

3. What is the output of this Swift code?

let x = 3; let y = 4
print(x + y)

medium

A. Syntax error

B. 34

C. 7

D. Runtime error

Solution

1. Step 1: Analyze semicolon usage

   The semicolon separates two statements on the same line, which is valid in Swift.

2. Step 2: Calculate the print output

   x is 3 and y is 4, so x + y equals 7, which is printed.

3. Final Answer:

   7 -> Option C

4. Quick Check:

   3 + 4 = 7 [OK]

Hint: Semicolons separate statements; addition works normally [OK]

Common Mistakes:

• Thinking semicolon causes syntax error
• Confusing concatenation with addition
• Expecting runtime error due to semicolon

4. Identify the error in this Swift code:

let a = 10 let b = 20
print(a + b)

medium

A. Variable names are invalid

B. Missing semicolon between statements on the same line

C. Missing parentheses in print statement

D. No error, code runs fine

Solution

1. Step 1: Check statement separation

   Two statements are on the same line without a semicolon separating them, which is invalid in Swift.

2. Step 2: Confirm print syntax and variable names

   Print statement and variable names are correct; only missing semicolon causes error.

3. Final Answer:

   Missing semicolon between statements on the same line -> Option B

4. Quick Check:

   Multiple statements same line need semicolon [OK]

Hint: Add semicolon between statements on the same line [OK]

Common Mistakes:

• Ignoring missing semicolon error
• Assuming print needs no parentheses
• Thinking variable names cause error

5. You want to write two Swift statements on the same line: let name = "Alice" and print(name). Which is the correct way to write this?

hard

A. let name = "Alice"; print(name)

B. let name = 'Alice'; print(name);

C. let name = "Alice" print(name);

D. let name = "Alice" print(name)

Solution

1. Step 1: Understand semicolon use on same line

   When writing multiple statements on the same line, separate them with a semicolon.

2. Step 2: Check each option for correctness

   let name = "Alice"; print(name) correctly separates the two statements with a semicolon and omits unnecessary semicolon at the end.

3. Final Answer:

   let name = "Alice"; print(name) -> Option A

4. Quick Check:

   Separate statements on one line with semicolon [OK]

Hint: Use one semicolon between statements on the same line [OK]

Common Mistakes:

• Omitting semicolon between statements
• Adding extra semicolon after last statement unnecessarily
• Writing statements without separation