How to initialize Kotlin IntArray from IntRange?

Question

I'm trying to initialize an IntArray in Kotlin like so:

intArrayOf(1..9)

But I get a TypeError that Int is required, but I'm providing an IntRange. Is there a way to initialize the array with a range, or do I have to explicitly write out each value?

zsmb13 · Accepted Answer · 2019-03-17 18:41:57Z

34

Using built in functions, this is how you could get to an IntArray from an IntRange:

val array: IntArray = (1..9).toList().toIntArray()

This is a bit wasteful, because it first constructs a list where it puts all the elements, and then it constructs an array as well. To do this directly, you could use your own extension, something like...

fun IntRange.toIntArray(): IntArray {
    if (last < first)
        return IntArray(0)

    val result = IntArray(last - first + 1)
    var index = 0
    for (element in this)
        result[index++] = element
    return result
}

Which would give you this syntax:

val array: IntArray = (1..9).toIntArray()

answered Mar 17, 2019 at 18:41

zsmb13

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