How does one pass an Array<Int> to a vararg Int function using the Spread Operator?
Basically, Array<Int> is an array of boxed Integer objects under the hood, while IntArray translates to an array of primitive int values (see this answer).
To pass in an Array<Int> to a vararg function, you can use the toIntArray() function to convert it to an IntArray first:
val numbers: Array<Int> = arrayOf(1, 2, 3)printNumbers(*numbers.toIntArray())Or if you can, create the array as an IntArray to begin with - this way you avoid the allocation of an extra array in the process, as well as the boxing of each individual value:
val numbers: IntArray = intArrayOf(1, 2, 3)printNumbers(*numbers)
The problem is that you're using the boxed Integers when creating an Array<Int>. This does not work well with vararg Int. It works with an IntArray though:
val numbers: Array<Int> = arrayOf(1, 2, 3)printNumbers(*numbers.toIntArray())Or directly create the array with the correct type:
val numbers = intArrayOf(1, 2, 3)printNumbers(*numbers)Using an IntArray, as opposed to Array<Int>, removes the boxing overhead, which surely is preferable.