krsort

(PHP 4, PHP 5, PHP 7, PHP 8)

krsort — Sort an array by key in descending order

Description

krsort(array &$array, int $flags = SORT_REGULAR): true

Sorts array in place by keys in descending order.

Note:
If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.

Note:
Resets array's internal pointer to the first element.

Parameters

array

The input array.

flags

The optional second parameter flags may be used to modify the sorting behavior using these values:

Sorting type flags:

SORT_REGULAR - compare items normally; the details are described in the comparison operators section
SORT_NUMERIC - compare items numerically
SORT_STRING - compare items as strings
SORT_LOCALE_STRING - compare items as strings, based on the current locale. It uses the locale, which can be changed using setlocale()
SORT_NATURAL - compare items as strings using "natural ordering" like natsort()
SORT_FLAG_CASE - can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively

Return Values

Always returns true.

Changelog

Version	Description
8.2.0	The return type is `true` now; previously, it was bool.

Examples

Example #1 krsort() example

<?php
$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
krsort($fruits);
foreach ($fruits as $key => $val) {
    echo "$key = $val\n";
}
?>

The above example will output:

d = lemon
c = apple
b = banana
a = orange

User Contributed Notes 2 notes

down

-24

peter at pmkmedia dot com ¶

21 years ago


Best deal sorting:

This is a function that will sort an array with integer keys (weight) and float values (cost) and delete 'bad deals' - entries that are more costly than other entries that have greater or equal weight.

Input: an array of unsorted weight/cost pairs
Output: none

function BEST_DEALS($myarray)
{   // most weight for least cost:
    // � Peter Kionga-Kamau, http://www.pmkmedia.com
    // thanks to Nafeh for the reversal trick
    // free for unrestricted use.
    krsort($myarray, SORT_NUMERIC);
    while(list($weight, $cost) = each($myarray))
    {   // delete bad deals, retain best deals:
        if(!$lastweight)
        {
            $lastweight=$weight;
            $lastcost = $cost;
        }
        else if($cost >= $lastcost) unset($myarray[$weight]);
        else
        {
            $lastweight=$weight;
            $lastcost = $cost;
        }
    }
    ksort($myarray);
}

down

-25

Anonymous ¶

19 years ago


To create a natural reverse sorting by keys, use the following function:

<?php
function natkrsort($array) 
{
    $keys = array_keys($array);
    natsort($keys);

    foreach ($keys as $k)
    {
        $new_array[$k] = $array[$k];
    }
   
    $new_array = array_reverse($new_array, true);

    return $new_array;
}
?>

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