arsort

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

    arsort — Sort an array in descending order and maintain index association

    Description

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

    Sorts array in place in descending order, such that its keys maintain their correlation with the values they are associated with.

    This is used mainly when sorting associative arrays where the actual element order is significant.

    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:

    Return Values

    Always returns true.

    Changelog

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

    Examples

    Example #1 arsort() example

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

    The above example will output:

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

    The fruits have been sorted in reverse alphabetical order, and the index associated with each element has been maintained.

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    User Contributed Notes 3 notes

    up
    13
    morgan at anomalyinc dot com
    24 years ago
    If you need to sort a multi-demension array, for example, an array such as

    $TeamInfo[$TeamID]["WinRecord"]
    $TeamInfo[$TeamID]["LossRecord"]
    $TeamInfo[$TeamID]["TieRecord"]
    $TeamInfo[$TeamID]["GoalDiff"]
    $TeamInfo[$TeamID]["TeamPoints"]

    and you have say, 100 teams here, and want to sort by "TeamPoints":

    first, create your multi-dimensional array. Now, create another, single dimension array populated with the scores from the first array, and with indexes of corresponding team_id... ie
    $foo[25] = 14
    $foo[47] = 42
    or whatever.
    Now, asort or arsort the second array.
    Since the array is now sorted by score or wins/losses or whatever you put in it, the indices are all hoopajooped.
    If you just walk through the array, grabbing the index of each entry, (look at the asort example. that for loop does just that) then the index you get will point right back to one of the values of the multi-dimensional array.
    Not sure if that's clear, but mail me if it isn't...
    -mo
    up
    11
    stephenakins at gmail dot com
    7 years ago
    I have two servers; one running 5.6 and another that is running 7. Using this function on the two servers gets me different results when all of the values are the same.

    <?php

    $list     = json_decode('{"706":2,"703":2,"702":2,"696":2,"658":2}', true);

    print_r($list);

    arsort($list);
    echo     "<br>";

    print_r($list);

    ?>

    PHP 5.6 results:
    Array ( [706] => 2 [703] => 2 [702] => 2 [696] => 2 [658] => 2 )
    Array ( [658] => 2 [696] => 2 [702] => 2 [703] => 2 [706] => 2 )

    PHP 7 results:
    Array ( [706] => 2 [703] => 2 [702] => 2 [696] => 2 [658] => 2 )
    Array ( [706] => 2 [703] => 2 [702] => 2 [696] => 2 [658] => 2 )
    up
    -1
    FatBat
    13 years ago
    Needed to get the index of the max/highest value in an assoc array.
    max() only returned the value, no index, so I did this instead.

    <?php
    reset    ($x); // optional.
    arsort($x);
    $key_of_max = key($x); // returns the index.
    ?>
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