reduceRightIndexed
inline fun <S, T : S> Array<out T>.reduceRightIndexed(
operation: (index: Int, T, acc: S) -> S
): S
(source)
inline fun ShortArray.reduceRightIndexed(
operation: (index: Int, Short, acc: Short) -> Short
): Short
(source)
inline fun FloatArray.reduceRightIndexed(
operation: (index: Int, Float, acc: Float) -> Float
): Float
(source)
inline fun DoubleArray.reduceRightIndexed(
operation: (index: Int, Double, acc: Double) -> Double
): Double
(source)
inline fun BooleanArray.reduceRightIndexed(
operation: (index: Int, Boolean, acc: Boolean) -> Boolean
): Boolean
(source)
Accumulates value starting with the last element and applying operation from right to left to each element with its index in the original array and current accumulator value.
Throws an exception if this array is empty. If the array can be empty in an expected way,
please use reduceRightIndexedOrNull instead. It returns null
when its receiver is empty.
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 an element, the element itself and current accumulator value,
and calculates the next accumulator value.
Accumulates value starting with the last element and applying operation from right to left to each element with its index in the original list and current accumulator value.
Throws an exception if this list is empty. If the list can be empty in an expected way,
please use reduceRightIndexedOrNull instead. It returns null
when its receiver is empty.
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 an element, the element itself and current accumulator value,
and calculates the next accumulator value.