Concatenate Swift Array of Int to create a new Int

Question

How can you make an Array<Int> ([1,2,3,4]) into a regular Int (1234)? I can get it to go the other way (splitting up an Int into individual digits), but I can't figure out how to combine the array so that the numbers make up the digits of a new number.

Answer 1

This will work:

let digits = [1,2,3,4]
let intValue = digits.reduce(0, combine: {$0*10 + $1})

For Swift 4+ :

let digits = [1,2,3,4]
let intValue = digits.reduce(0, {$0*10 + $1})

Or this compiles in more versions of Swift:

(Thanks to Romulo BM.)

let digits = [1,2,3,4]
let intValue = digits.reduce(0) { return $0*10 + $1 }

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NOTE

This answer assumes all the Ints contained in the input array are digits -- 0...9 . Other than that, for example, if you want to convert [1,2,3,4, 56] to an Int 123456, you need other ways.