Operator overloading concept in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of custom operator overloading

What is the output of this Swift code that overloads the + operator for a custom struct?

Swift

struct Point {
    var x: Int
    var y: Int

    static func + (lhs: Point, rhs: Point) -> Point {
        Point(x: lhs.x + rhs.x, y: lhs.y + rhs.y)
    }
}

let p1 = Point(x: 3, y: 4)
let p2 = Point(x: 5, y: 7)
let p3 = p1 + p2
print("(\(p3.x), \(p3.y))")

A (35, 47)

B (15, 28)

C (8, 11)

D Compilation error

💡 Hint

Think about how the + operator is defined for Point and what it returns.

The + operator is overloaded to add the x and y values of two Point instances. So (3+5, 4+7) = (8, 11).

🧠 Conceptual

intermediate

Purpose of operator overloading

Why do programmers use operator overloading in Swift?

A To automatically generate UI elements for custom types

B To prevent the use of operators on custom types

C To make the code run faster by replacing operators with functions

D To allow custom types to use standard operators like + or * with meaningful behavior

💡 Hint

Think about how operators work with built-in types and why you might want the same for your own types.

Operator overloading lets you define how operators like +, -, * behave with your own types, making code easier to read and write.

🔧 Debug

advanced

Identify the error in operator overloading

What error does this Swift code produce when trying to overload the * operator for a struct?

Swift

struct Vector {
    var value: Int

    static func * (lhs: Vector, rhs: Vector) -> Int {
        lhs.value * rhs.value
    }
}

let v1 = Vector(value: 2)
let v2 = Vector(value: 3)
let result = v1 * v2
print(result)

A No error, prints 6

B Type mismatch error because operator * must return Vector, not Int

C Syntax error due to missing return keyword

D Runtime error because operator * is not defined for Vector

💡 Hint

Check the return type of the operator function and how it is used.

The operator * is defined to return Int, which is allowed. The code prints 6 correctly.

❓ Predict Output

advanced

Output of prefix operator overloading

What is the output of this Swift code that overloads the prefix - operator for a struct?

Swift

struct Temperature {
    var celsius: Double

    static prefix func - (value: Temperature) -> Temperature {
        Temperature(celsius: -value.celsius)
    }
}

let temp = Temperature(celsius: 25.0)
let negTemp = -temp
print(negTemp.celsius)

A -25.0

B 25.0

C Compilation error

D 0.0

💡 Hint

Consider what the prefix - operator does to the celsius value.

The prefix - operator returns a new Temperature with the negative of the original celsius value, so -25.0 is printed.

📝 Syntax

expert

Correct syntax for custom infix operator

Which option correctly declares and implements a custom infix operator ** for exponentiation on Int in Swift?

A

infix operator **
extension Int {
    func ** (power: Int) -> Int {
        Int(pow(Double(self), Double(power)))
    }
}

B

infix operator ** {}
extension Int {
    static func ** (base: Int, power: Int) -> Int {
        Int(pow(Double(base), Double(power)))
    }
}

C

operator infix ** {
extension Int {
    func ** (power: Int) -> Int {
        Int(pow(Double(self), Double(power)))
    }
}

D

infix operator **
extension Int {
    static func ** (base: Int, power: Int) -> Int {
        pow(base, power)
    }
}

💡 Hint

Remember that operator functions must be static and the operator must be declared before use.

Option B correctly declares the infix operator and defines a static function with proper types and return value.