3Beard 3Beard - 1 month ago 11
Swift Question

Swift 3 comparing array indexes

If i have two arrays & i want to compare their indexes, for ex:

let var a1 = ["1", "2", "3"]
let var a2 = ["3", "2", "3"]


And i wanted to print something to say which index wasn't the same, such as:

if a1[0] != a2[0] && a1[1] == a2[1] && a1[2] == a2[2]{
print("Index 0 is not the same.")


Would i have to write 7 more of those statements to show all 8 possibilities of all correct/all wrong/index 1&1 wrong, etc?

Thank you!

Answer

You can get all indexes like this:

let diffIndex = zip(a1, a2).enumerated().filter {$1.0 != $1.1}.map {$0.offset}

Explanation:

  • zip produces a sequence of pairs
  • enumerated() adds an index to the sequence
  • filter keeps only pairs with different values
  • map harvests the index, and builds the sequence of results.

Running this on

let a1 = ["1", "2", "3", "4"]
let a2 = ["3", "2", "3", "5"]

This produces a sequence [0, 3]