Ds\Map::ksort

Sorts the map in-place by key.

Description

public void Ds\Map::ksort ([ callable $comparator ] )

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. Note that before PHP 7.0.0 this integer had to be in the range from -2147483648 to 2147483647.

int callback ( mixed $a, mixed $b )

Caution
Returning non-integer values from the comparison function, such as float, will result in an internal cast to integer 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
        )

)