Kotlin List reduceRight()
Syntax & Examples

Syntax of List.reduceRight()

The syntax of List.reduceRight() extension function is:

fun <S, T : S> List<T>.reduceRight( operation: (T, acc: S) -> S ): S

This reduceRight() extension function of List accumulates value starting with the last element and applying operation from right to left to each element and current accumulator value.


✐ Examples

1 Example

In this example,

  • We create a list named list containing the integers [1, 2, 3, 4, 5].
  • We use the reduceRight function to accumulate values starting with the last element.
  • In the operation, element represents the current element, and acc represents the accumulator value.
  • We subtract each element from the accumulator from right to left.
  • Finally, we print the result to standard output using the println function.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(1, 2, 3, 4, 5);
    val result = list.reduceRight { element, acc -> acc - element };
    println(result);
}

Output

-5

2 Example

In this example,

  • We create a list named list containing the strings ['apple', 'banana', 'cherry', 'date', 'elderberry'].
  • We use the reduceRight function to accumulate values starting with the last element.
  • In the operation, element represents the current element, and acc represents the accumulator value.
  • We add each string to the accumulator from right to left.
  • Finally, we print the result to standard output using the println function.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf("apple", "banana", "cherry", "date", "elderberry");
    val result = list.reduceRight { element, acc -> acc + " " + element };
    println(result);
}

Output

elderberry date cherry banana apple

Summary

In this Kotlin tutorial, we learned about reduceRight() extension function of List: the syntax and few working examples with output and detailed explanation for each example.