PHP Unconference Europe 2015

arsort

(PHP 4, PHP 5)

arsortOrdena um array em ordem descrescente mantendo a associação entre índices e valores

Descrição

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

Esta função ordena um array de forma que a correlação entre índices e valores é mantida.

É usada principalmente para ordenar arrays associativos onde a ordem dos elementos é um fator importante.

Parâmetros

array

O array de entrada.

sort_flags

Você pode modificar o comportamento da ordenação usando o parâmetro opcional sort_flags, para detalhes veja sort().

Valor Retornado

Retorna TRUE em caso de sucesso ou FALSE em caso de falha.

Exemplos

Exemplo #1 Exemplo da arsort()

<?php
$frutas 
= array("d" => "limao""a" => "laranja""b" => "banana""c" => "melancia");
arsort($frutas);
foreach (
$frutas as $chave => $valor) {
    echo 
"$chave = $valor\n";
}
?>

O exemplo acima irá imprimir:

c = melancia
d = limao
a = laranja
b = banana

As frutas foram ordenadas na ordem alfabética inversa, e os índices associados a cada valor foram mantidos.

Veja Também

  • asort() - Ordena um array mantendo a associação entre índices e valores
  • rsort() - Ordena um array em ordem descrescente
  • ksort() - Ordena um array pelas chaves
  • sort() - Ordena um array

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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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