Ds\Map::ksort

    (PECL ds >= 1.0.0)

    Ds\Map::ksort — Sorts the map in-place by key

    Description

    public Ds\Map::ksort(callable $comparator = ?): void

    Sorts the map in-place by key, using an optional comparator function.

    Parameters

    comparator

    The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

    callback(mixed $a, mixed $b): int
    Caution

    Returning non-integer values from the comparison function, such as float, will result in an internal cast to int of the callback's return value. So values such as 0.99 and 0.1 will both be cast to an integer value of 0, which will compare such values as equal.

    Return Values

    No value is returned.

    Examples

    Example #1 Ds\Map::ksort() example

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

    print_r($map);
    ?>

    The above example will output something similar to:

    Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => a
            [value] => 1
        )

    [1] => Ds\Pair Object
        (
            [key] => b
            [value] => 2
        )

    [2] => Ds\Pair Object
        (
            [key] => c
            [value] => 3
        )

)

    Example #2 Ds\Map::ksort() example using a comparator

    <?php
    $map     = new \Ds\Map([1 => "x", 2 => "y", 0 => "z"]);

    // Reverse
    $map->ksort(function($a, $b) {
    return     $b <=> $a;
    });

    print_r($map);
    ?>

    The above example will output something similar to:

    Ds\Map Object
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => 2
            [value] => y
        )

    [1] => Ds\Pair Object
        (
            [key] => 1
            [value] => x
        )

    [2] => Ds\Pair Object
        (
            [key] => 0
            [value] => z
        )

)

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