arsort

(PHP 4, PHP 5)

arsortSort an array in reverse order and maintain index association

Descrierea

bool arsort ( array &$array [, int $sort_flags = SORT_REGULAR ] )

This function sorts an array such that array indices maintain their correlation with the array elements they are associated with.

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

Parametri

array

The input array.

sort_flags

You may modify the behavior of the sort using the optional parameter sort_flags, for details see sort().

Valorile întoarse

Întoarce valoarea TRUE în cazul succesului sau FALSE în cazul eșecului.

Exemple

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";
}
?>

Exemplul de mai sus va afișa:

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.

Vedeți de asemenea

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User Contributed Notes 5 notes

up
4
morgan at anomalyinc dot com
14 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
0
FatBat
3 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.
?>
up
0
rodders_plonker at yahoo dot com
14 years ago
I was having trouble with the arsort() function on an older version of PHP which was returning an error along the lines of 'wrong perameter count for function arsort' when I tried to use a flag for numeric sorting (2/SORT_NUMERIC).
I figured, as I only wanted to sort integers, I could pad numbers from the left to a specific length with 0's (using the lpad function provided by improv@magma.ca in the notes at http://www.php.net/manual/ref.strings.php).
A string sort then correctly sorts numerically (i.e. {30,2,10,21} becomes {030,021,010,002} not {30,21,2,10}) when echoing the number an (int)$string_name hides the leading 0's.

Made my day :).

Rodders.
up
-3
jordancdarwin at googlemail dot com
6 years ago
A lot of people seem to trip up on this and ask me questions as to debugging. Bear in mind that this returns boolean, and does not return an array of affected items.

$array = array("One"=>1, "Three" => 3,"Two" =>2);
print_r(asort($array));

If successful, will return 1, and error if there is a string used. Useful to note so then people stop asking me :D
up
-4
sebas2day
2 years ago
If you are dealing with a multidimensional array you want to sort, then this might be helpfull:

<?php
function array_sort($arr){
    if(empty(
$arr)) return $arr;
    foreach(
$arr as $k => $a){
        if(!
is_array($a)){
           
arsort($arr); // could be any kind of sort
           
return $arr;
        }else{
           
$arr[$k] = array_sort($a);
        }
    }
    return
$arr;
}
?>
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