International PHP Conference Munich 2021

krsort

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

krsortSort an array by key in descending order

Description

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

Sorts an array by key in descending order, maintaining key to data correlations. This is useful mainly for associative arrays.

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

Returns true on success or false on failure.

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

See Also

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User Contributed Notes 2 notes

up
-28
peter at pmkmedia dot com
17 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);
}
up
-31
Anonymous
15 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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