reduceRight()

The reduceRight() method all similar to reduce(), but It works in reverse order.

Example.php
<?php use kim\present\utils\arrays\ArrayUtils;

$arrayUtils = ArrayUtils::from(range(1, 10));

//This is like a 10 factorial
$arrayUtils->reduceRight(function($accumulator, $value){ return $accumulator * $value; }, 1);
// expected output: 3628800



$arrayUtils->reduceRight(
    function($accumulator, $value){
        echo  "$accumulator * $value = " . ($accumulator * $value) . PHP_EOL;
        return $accumulator * $value; }, 1));
//echo 1 * 10 = 10
//echo 10 * 9 = 90
//echo 90 * 8 = 720
//echo 720 * 7 = 5040
//echo 5040 * 6 = 30240
//echo 30240 * 5 = 151200
//echo 151200 * 4 = 604800
//echo 604800 * 3 = 1814400
//echo 1814400 * 2 = 3628800
//echo 3628800 * 1 = 3628800
//expected output: 3628800

Syntax

$arrayUtils->reduceRight(callable $callback, mixed $initialValue = null) : mixed;

Parameter

  • $callback

    A function that produces an element of the new Array, taking four arguments:

    • $accumulatorThe accumulator accumulates callback's return values. It is the accumulated value previously returned in the last invocation of the callback—or $initialValue, if it was supplied (see below).

    • $value The current element being processed in the array.

    • $key The index of the current element being processed in the array.

    • $array The array every was called upon.

    • A value to use as the first argument to the first call of the callback.

Return value

  • The result value.

Prefixing

ArrayUtils::reduceRightFrom(iterable $from, callable $callback, mixed $initialValue = null) : mixed;

References

pagereduce()

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