Numeric literal formats in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of integer literals with underscores

What is the output of this Swift code?

let number = 1_000_000
print(number)

Swift

let number = 1_000_000
print(number)

A 1000000

B 100000

C 1000_000

D 1_000_000

💡 Hint

Underscores in numeric literals are ignored by the compiler and used only for readability.

In Swift, underscores in numeric literals are ignored when the number is compiled. So 1_000_000 is the same as 1000000.

❓ Predict Output

intermediate

Output of hexadecimal floating-point literal

What is the output of this Swift code?

let hexFloat = 0xFp2
print(hexFloat)

Swift

let hexFloat = 0xFp2
print(hexFloat)

A 15.0

B 60.0

C 240.0

D 30.0

💡 Hint

0xF is 15 in decimal. The p2 means multiply by 2 to the power of 2.

0xF is 15 decimal. p2 means multiply by 2^2 = 4. So 15 * 4 = 60.0.

🔧 Debug

advanced

Identify the error in numeric literal

Which option will cause a compile-time error in Swift due to invalid numeric literal format?

A let num = 0o755

B let num = 0x1A3F

C let num = 1_000_000

D let num = 0b102

💡 Hint

Binary literals can only contain 0 or 1 digits.

0b102 is invalid because binary literals can only have digits 0 or 1. The digit '2' is not allowed.

❓ Predict Output

advanced

Output of floating-point literal with exponent

What is the output of this Swift code?

let value = 1.25e3
print(value)

Swift

let value = 1.25e3
print(value)

A 0.00125

B 1.25

C 1250.0

D 125.0

💡 Hint

The e3 means multiply by 10 to the power of 3.

1.25e3 means 1.25 * 10^3 = 1250.0.

🧠 Conceptual

expert

Number of items in dictionary from numeric literal keys

What is the number of items in the dictionary created by this Swift code?

let dict = [0x1: "one", 0b1: "binary one", 1: "decimal one"]
print(dict.count)

Swift

let dict = [0x1: "one", 0b1: "binary one", 1: "decimal one"]
print(dict.count)

A 1

B 3

C 2

D 0

💡 Hint

All keys represent the same integer value 1 in different numeric literal formats.

0x1, 0b1, and 1 all represent the integer 1, so the dictionary has only one unique key.