Today I learned: ```fun foo(args: IntArray) { ...

# getting-started

[Klitos Kyriacou]

Today I learned:

fun foo(args: IntArray) {
    val a = intArrayOf(*args)  // Creates a copy of args
    //val b = intArrayOf(args)  // Compile error
    val c = intArrayOf(elements = args)
}

To pass an array to a varargs parameter, we are supposed to use the spread operator *. But that creates a copy of the array, which you might not want to do if you are calling a pure function in a loop. You can't pass the array itself, but I learned that you can pass it if you use a named parameter! Where in the documentation does it say that?

[Update: looking at the generated bytecode, the call intArrayOf(elements = args) also copies the array, and produces the same bytecode as using the spread operator.]

[Youssef Shoaib [MOD]]

I'm guessing that passing it using a named parameter specifies the intent that you would like to treat the parameter as an array instead of a varargs parameter. I think the only reason that this is a thing is to prevent ambiguity where in certain generic situations an array could either be meant as a singular argument to a varargs parameter or it could be meant as a replacement for the varargs parameter

[Youssef Shoaib [MOD]]

In other words, think of the difference between:

fun foo(args: IntArray) {
    val a = listOf(*args)  // Creates a copy of args and creates a list containing the elements of args
    val c = listOf(args) // Creates a list that contains the array args
}