kotlin-stdlib / kotlin.text / reduceRightIndexed

reduceRightIndexed

Common
JVM
JS
Native
1.0
inline fun CharSequence.reduceRightIndexed(
    operation: (index: Int, Char, acc: Char) -> Char
): Char

Accumulates value starting with last character and applying operation from right to left to each character with its index in the original char sequence and current accumulator value.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val strings = listOf("a", "b", "c", "d")
println(strings.reduceRight { string, acc -> acc + string }) // dcba
println(strings.reduceRightIndexed { index, string, acc -> acc + string + index }) // dc2b1a0

// emptyList<Int>().reduceRight { _, _ -> 0 } //  will fail
//sampleEnd
}

Parameters

operation - function that takes the index of a character, the character itself and current accumulator value, and calculates the next accumulator value.