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Ds\Map::reduce

(PECL ds >= 1.0.0)

Ds\Map::reduceReduces the map to a single value using a callback function

Descrierea

public Ds\Map::reduce ( callable $callback [, mixed $initial ] ) : mixed

Reduces the map to a single value using a callback function.

Parametri

callback
callback ( mixed $carry , mixed $key , mixed $value ) : mixed
carry

The return value of the previous callback, or initial if it's the first iteration.

key

The key of the current iteration.

value

The value of the current iteration.

initial

The initial value of the carry value. Can be NULL.

Valorile întoarse

The return value of the final callback.

Exemple

Example #1 Ds\Map::reduce() with initial value example

<?php
$map 
= new \Ds\Map(["a" => 1"b" => 2"c" => 3]);

$callback = function($carry$key$value) {
    return 
$carry $value;
};

var_dump($map->reduce($callback5));

// Iterations:
//
// $carry = $initial = 5
//
// $carry = $carry * 1 =  5
// $carry = $carry * 2 = 10
// $carry = $carry * 3 = 30
?>

Exemplul de mai sus va afișa ceva similar cu:

int(30)

Example #2 Ds\Map::reduce() without an initial value example

<?php
$map 
= new \Ds\Map(["a" => 1"b" => 2"c" => 3]);

var_dump($map->reduce(function($carry$key$value) {
    return 
$carry $value 5;
}));

// Iterations:
//
// $carry = $initial = null
//
// $carry = $carry + 1 + 5 =  6
// $carry = $carry + 2 + 5 = 13
// $carry = $carry + 3 + 5 = 21
?>

Exemplul de mai sus va afișa ceva similar cu:

int(21)
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