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iOS Swift Closures Functions as First Class Citizens Higher Order Functions

kirkbyo
kirkbyo
15,791 Points
Posted by kirkbyo
kirkbyo
15,791 Points

Trouble computing the difference between two integers.

I am having trouble locating where I went wrong with task 2 of this challenge.

Questions:

Using the differenceBetweenNumbers function as an input to mathOperation, compute the difference between any two integers and assign the result to a constant named difference.

Error:

Bummer! Make sure you are computing the difference between two integers using the functions created and assigning the result to a constant named difference.

My Code:

func differenceBetweenNumbers(a: Int, b:Int) -> (Int) {
    return a - b
}

func mathOperation(mathFunc: (Int, Int) -> (Int), a: Int, b: Int) -> Int {
    return mathFunc(a, b)
}

let difference = mathOperation(differenceBetweenNumbers, 20, 10)

Ozzie

1 Answer

agreatdaytocode
agreatdaytocode
24,757 Points

Your code looks fine. This worked for me. I used someOperationFunc(a,b)

func mathOperation(someOperationFunc: (Int, Int) -> Int, a: Int, b: Int) -> Int {
    return someOperationFunc(a, b)
}

let difference = mathOperation(differenceBetweenNumbers, 26, 22)
kirkbyo
kirkbyo
15,791 Points
kirkbyo
kirkbyo
15,791 Points

The error was caused by having the function parameter return being wrapped in parathesis.

// Does Not Work in the challenge. 
func mathOperation(mathFunc: (Int, Int) -> (Int), a: Int, b: Int) -> Int {
    return mathFunc(a, b)
}

// Works
func mathOperation(mathFunc: (Int, Int) -> Int, a: Int, b: Int) -> Int {
    return mathFunc(a, b)
}

Anyways, thanks for your help!

Ozzie

Wei Wen
Wei Wen
2,995 Points

What is the difference between Int and (Int)?

Nehemiah Reese
Nehemiah Reese
17,692 Points

Why isn't it:

let difference = mathOperation(differenceBetweenNumbers() , 26, 22)

Is the function a constant being passed in?