Changing the name of an array in a for-in loop

Question

I have a set number of arrays that I need to loop through. There is only one difference in their names, and that is a number at the end of it.

arr1
arr2
arr3

I want to get the first number from the first array, the second number from the second array and so on. I also have a number n that contains the number of how many arrays and number of arrays there are. If there are two arrays, they each have two numbers, if there are three arrays they each have three numbers, etc.

Originally I was looping through it like this:

var firstDiag = 0

for (var i = 0; i < n; i++) {
    if (i == 0) {
        firstDiag += Int(arr1[i])!
    } else if (i == 1) {
        firstDiag += Int(arr2[i])!
    } else if (i == 2) {
        firstDiag += Int(arr3[i])!
    } else {
        firstDiag += 0
    }
}

But I was wondering if I could somehow do it this way

for i in 0...n {
  firstDiag += Int(arr<i>[i])!
}

Where I change the last number on the array name. Is it possible to do this, or is there something else I should be doing?

There is the possibility I don't know how many arrays there are.

Create an array of your arrays let arr = [arr1, arr2, arr3] then you can do firstDiag += Int(arr[i][i])! — vacawama
– vacawama, Commented Jan 1, 2016 at 16:22
@vacawama you should post it as answer so you can get credits ;-) — Stefan
– Stefan, Commented Jan 4, 2016 at 13:52
@vacawama, I did edit my post with a little more information at the bottom. — Caleb Kleveter
– Caleb Kleveter, Commented Jan 4, 2016 at 13:53

sunshinejr · Accepted Answer · 2016-01-01 16:39:16Z

1

If you can create a class that conforms to NSKeyValueCoding, you can use valueForKeyPath(_:) to get what you want. Example of the usage would be:

import Foundation
class Test: NSObject {

    let array0 = [1, 2, 3]
    let array1 = [4, 5, 6]
    let array2 = [7, 8, 9]
    let n = 3

    func calculate() -> Int {
        var firstDiag = 0
        for i in 0..<n {
            if let array = valueForKeyPath("array\(i)") as? Array<Int> {
                firstDiag += array[i]
            }
        }

        return firstDiag
    }
}

let a = Test()
a.calculate() // Prints 15

answered Jan 1, 2016 at 16:39

sunshinejr

4,8442 gold badges24 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Changing the name of an array in a for-in loop

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related