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iOS Swift Closures Functions as First Class Citizens Higher Order Functions

Michael Mac Coisdeala
Michael Mac Coisdeala
4,212 Points

Why is my answer not being accepted? It works when I enter it in Xcode

I've entered the code into Xcode and it works just fine. What am I doing wrong?

higherOrderFunctions.swift
/** 
  For this code challenge, let’s define a math operation as a function that 
  carries out some work on two integers and returns an integer as well. An 
  example is the function below, `differenceBetweenNumbers`, which takes two 
  integers and calculates the difference between the numbers. After calculating, 
  it returns the difference.
*/

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

// Enter your code below
func mathOperation(f: ((Int, Int) -> Int), c: Int, d: Int) -> Int {
  return f(c, d)
}
let difference = mathOperation(differenceBetweenNumbers, 9, 7)

1 Answer

Martin Wildfeuer
PLUS
Martin Wildfeuer
Courses Plus Student 11,071 Points

For the sake of this course you should omit the additional parenthesis. Although it works in Xcode, the code check here is a bit picky. Therefore, change your code from

func mathOperation(f: ((Int, Int) -> Int), c: Int, d: Int) -> Int {
  return f(c, d)
}

to

func mathOperation(f: (Int, Int) -> (Int), c: Int, d: Int) -> Int {
    return f(c, d)
}
Michael Mac Coisdeala
Michael Mac Coisdeala
4,212 Points

Tried this and it is still not working. It is in the second objective where the problem arises where it asks : "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".