International PHP Conference 2019 - Spring Edition

Ds\Set::reduce

(PECL ds >= 1.0.0)

Ds\Set::reduceReduces the set to a single value using a callback function

说明

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

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

参数

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

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

value

The value of the current iteration.

initial

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

返回值

The return value of the final callback.

范例

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

<?php
$set 
= new \Ds\Set([123]);

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

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

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

以上例程的输出类似于:

int(30)

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

<?php
$set 
= new \Ds\Set([123]);

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

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

以上例程的输出类似于:

int(21)
add a note add a note

User Contributed Notes

There are no user contributed notes for this page.
To Top