Variadic Functions in Kotlin

Here’s how the variadic function example can be translated into Kotlin:

Example: Variadic Functions

Variadic functions can be called with any number of trailing arguments. For example, println is a common variadic function.

Code Example#

Here’s a function that will take an arbitrary number of Ints as arguments.

fun sum(vararg nums: Int) {
    println(nums.joinToString(" "))
    var total = 0
    for (num in nums) {
        total += num
    }
    println(total)
}

fun main() {
    sum(1, 2)
    sum(1, 2, 3)
    val nums = intArrayOf(1, 2, 3, 4)
    sum(*nums)
}

Within the function, the type of nums is equivalent to IntArray. We can get its length using nums.size, iterate over it with for, and so on.

Running the Code#

To run the above program, put the code in a Kotlin file and execute it with Kotlin compiler.

$ kotlinc variadic-functions.kt -include-runtime -d variadic-functions.jar
$ java -jar variadic-functions.jar
[1, 2] 3
[1, 2, 3] 6
[1, 2, 3, 4] 10

Variadic functions can be called in the usual way with individual arguments.

If you already have multiple arguments in an array, apply them to a variadic function using * like this.

Another key aspect of functions in Kotlin is their ability to use higher-order functions and lambdas, which we’ll look at next.

Next example: Closures.