How do I say “if x == A or B or C” as succinctly in Swift as possible?

Question

I often encounter the following kind of situation in Swift code:

if x == A || x == B {
    // do something
}

Is there any way to shorten it?

What could A,B or C be in terms of data types? can help determine if there is a better way — Fonix, Dec 01 '16 at 07:16
I just wonder if there's a simpler way. Question is valid for any data type. — Barış Özçelik, Dec 01 '16 at 07:19
Another one here: http://stackoverflow.com/questions/37345267/any-way-to-chain-and-operands. — Martin R, Dec 01 '16 at 07:53

score 8 · Answer 1 · answered Dec 01 '16 at 07:18

8

I like switch statements for cases like this

switch x {
    case A, B, C:
        // do stuff
    case D:
       // other stuff
    default:
      // do default stuff
}

answered Dec 01 '16 at 07:18

hooliooo

Sahil · Answer 2 · 2016-12-01T07:24:44.673

2

Use Array instead, if all values of same type. if you just want to check x is matching to any values.

for example:

let x = 10
let A = 20
let B = 40
let C = 40


let myArray = [A, B,C]


if myArray.contains(x) {
  // do something
}

edited Dec 01 '16 at 07:24

answered Dec 01 '16 at 07:18

Sahil

In terms of search item in collection `Set` will be faster. `Array` would be `O(n)` and `Set` using hashes would be somewhere near `O(log(n))` on average. – user28434'mstep Dec 01 '16 at 07:29
1

@user28434 For this few elements, the overhead of hashing would be **way** slower than linear search – Alexander Dec 01 '16 at 07:47
@AlexanderMomchliov, indeed, if author really needs to compare only 3 elements. – user28434'mstep Dec 01 '16 at 07:49

score 0 · Answer 3 · answered Dec 01 '16 at 07:26

0

if (x ^ A) * (x ^ B) * (x ^ C) == 0 {
    //do what you need
}

Shorter? Not sure... More impressive? Definitely.

answered Dec 01 '16 at 07:26

Max Pevsner

`|` would be faster than `*` – Alexander Dec 01 '16 at 07:47
1

Will only work if `x`, `A`, `B`, `C` are conforming to `BitwiseOperations` protocol (if `^` and `|` is used), and for `*` you need extra protocol conformance. And to compare it with `0` you also need to define `==` with left operand being `x`'s type, and right being `Int`. So that solution only works on really small subset of types, or if `x` is some kind of `Int`, and it may not be. – user28434'mstep Dec 01 '16 at 07:54
Also it does not short-circuit as the `||` operator does. – Martin R Dec 01 '16 at 07:55

3 Answers3