uksort

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

uksort — Ordena um array pelas chaves utilizando uma função de comparação definida pelo usuário.

Descrição

uksort(array &$array, callable $callback): true

Ordena o array pelas chaves usando uma função de comparação fornecida pelo usuário para determinar a ordem.

Nota:
Se dois elementos são comparados como iguais, eles mantêm sua ordem original. Antes do PHP 8.0.0, sua ordem relativa no array ordenado era indefinida.

Nota:
Redefine o ponteiro interno do array para o primeiro elemento.

Parâmetros

array: O array de entrada.
callback: A função de comparação deve retornar um inteiro menor que, igual ou maior que zero se o primeiro argumento for considerado respectivamente menor que, igual ou maior que o segundo.

callback(mixed $a, mixed $b): int

Cuidado
Retornar valores não inteiros da função de comparação, como float, resultará em uma conversão interna do valor retornado da função callback para int. Portanto, valores como 0.99 e 0.1 serão convertidos para o valor inteiro 0, o que comparará esses valores como iguais.

Valor Retornado

Sempre retorna true.

Registro de Alterações

Versão	Descrição
8.2.0	O tipo do retorno agora é `true`; anteriormente, era bool.
8.0.0	Se a função `callback` espera que um parâmetro seja passado por referência, esta função agora emitirá um `E_WARNING`.

Exemplos

Exemplo #1 uksort() example

<?php
function cmp($a, $b)
{
    $a = preg_replace('@^(a|an|the) @', '', $a);
    $b = preg_replace('@^(a|an|the) @', '', $b);
    return strcasecmp($a, $b);
}

$a = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);

uksort($a, "cmp");

foreach ($a as $key => $value) {
    echo "$key: $value\n";
}
?>

O exemplo acima produzirá:

an apple: 3
a banana: 4
the Earth: 2
John: 1

Veja Também

usort() - Ordena um array pelos valores utilizando uma função de comparação definida pelo usuário
uasort() - Ordena um array com uma função de comparação definida pelo usuário e mantém associações de índices
Comparação entre as funções de ordenação de array

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Notas Enviadas por Usuários (em inglês) 17 notes

down

580

PHPUser ¶

9 years ago

[Editor's note: the following comment may be factually incorrect]



uksort is only usable in the UK

<?php

if($country=="UK"){

  uksort();

}else{

  echo "You have to live in UK to use uksort().";

}

?>

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ingo at example dot test ¶

10 years ago

sort with collation, to have umlauts correctly:

uksort($retval, array(Collator::create( 'de_DE' ), 'compare'));

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fabriceb at gmx dot net ¶

20 years ago

(about sorting an array of objects by their properties in a class - inspired by webmaster at zeroweb dot org at usort function)
I'm using classes as an abstraction for querying records in a database and use arrays of objects to store records that have an 1 to n relationship. E.g. a class "family" has family members stored as an array of objects. Each of those objects prepresents a record in a database related to the family (by it's familyId).

To identify members, I'm using their memberId as the key of the array e.g. $family->members[$memberId].
To sort the family members AFTER fetching them with the database query, you can use the functions _objSort and sortMembers which will sort the "members" array by key using it's properties (for space reasons I didn't include the methods used to open the records):
<?php
class familyMember
{
    var $memberId;
    var $familyId;
    var $firstName;
    var $age;
    var $hairColor;
// ...
}

class family
{
    var $familyId;
    var $name;
    var $members = array(); // array of familyMember objects
    var $sortFields = array();
    var $sortDirections = array();
    // ...
    function _objSort(&$a, &$b, $i = 0)
    {
        $field        = $this->sortFields[$i];
        $direction    = $this->sortDirections[$i];
        
        $diff = strnatcmp($this->details[$a]->$field, $this->details[$b]->$field) * $direction;
        if ($diff == 0 && isset($this->sortFields[++$i]))
        {
            $diff = $this->_objSort($a, $b, $i);
        }
        
        return $diff;
    }
    
    function sortMembers($sortFields)
    {
        $i = 0;
        foreach ($sortFields as $field => $direction)
        {
            $this->sortFields[$i] = $field;
            $direction == "DESC" ? $this->sortDirections[$i] = -1 : $this->sortDirections[$i] = 1;
            $i++;
        }
        
        uksort($this->details, array($this, "_objSort"));
        
        $this->sortFields = array();
        $this->sortDirections = array();
    }
}
// open a family
$familyId = 5;
$family = new family($familyId);
$family->open(); // this will also fetch all members

// sort members by 3 fields
$family->sortMembers(array("firstName" => "ASC", "age" => "DESC", "hairColor" => "ASC"));
// output all family members
foreach ($family->members as $member)
{
    echo $member->firstName." - ".$member->age." - ".$member->hairColor."<br />";
}
?>

Note that this might not be the fastest thing on earth and it hasn't been tested very much yet but I hope it's useful for someone.

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mdsky at web dot de ¶

14 years ago

Case insensitive without own function:

uksort($array, "strnatcasecmp");

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aleczapka at gmx dot net ¶

19 years ago

One remark regarding array_sorter class.
It won't work correctly with eg. dates from mysql like 20041206105350, cause you can't convert such number into integer. To fix it remove intval() from the code. If the variable is a number it will work without converting this to int anyways. Here is the fix.

<?php
....
if ($a == $b) 
    return 0;
if ($this->sasc)
    return ($a > $b) ? 1 : -1;
else
    return ($a > $b) ? -1 : 1;
...
?>

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guss at typo dot co dot il ¶

20 years ago

Regarding the recursive sorting function above:
Genrally speaking, any recursion can be reimplemented using simple iteration. in the specific case, using recursion to compare strings has a huge performance impact while a simple loop would suffice and be faster and more simple. 
Recursion is only good if it simplifies your code or your understanding of the concept. the previous example does neither, especially as it does a lot of repetitive things in each iteration, such as asigning the character order constant, rebuilding it into an array and such

For example, the string comparison could be written as such : 
function str_compare($a,$b) {
    $order="aA??bBcC&#269;&#268;..."; // longer normally & without that html entities
    $default = strlen($a) - strlen($b);
    $minlen = strlen($a) < strlen($b) ? strlen($a) : strlen($b);
    for ($i = 0; $i < $minlen; $i++) {
        $pos_a=strpos($order,$a[$i]);
        $pos_b=strpos($order,$b[$i]);
        if ($pos_a != $pos_b)
            return $pos_a - $pos_b;
    }
    return $default;
}

Which is much simpler and faster.
Note that the above function will break for characters that are not listed in $order. it should be failry trivial to fix it.

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contacto at hardcode dot com dot ar ¶

15 years ago

need a case insensitive sort by key function? i did and couldn find it, so:



<?php

function insensitive_uksort($a,$b) {

    return strtolower($a)<strtolower($b);

}

uksort($arr, "insensitive_uksort");

?>

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aleczapka at gmx dot net ¶

19 years ago

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brian dot short at gmail dot com ¶

15 years ago

If you need to periodically sort by grades (A, A+, D-, etc.), here is a compare function that compares strings by the case-insensitive method, unless it finds a grade, in which case it correctly sorts by putting "plus" grades first, unmarked grades second, and "minus" grades last.



<?php

function cmp($a, $b)

{

   $a = preg_replace('@^(a|an|the) @', '', $a);

   $b = preg_replace('@^(a|an|the) @', '', $b);



   //special code for grades

   if (strpos( $a, "+") !== false || strpos( $b, "+") !== false  || 

       strpos( $a, "-") !== false || strpos( $b, "-") !== false ){



        $substrA = substr($a, 0, 1);

        $substrB = substr($b, 0, 1);        



        $modifierA = (strlen($a) == 2) ? substr($a, 1, 1) : "";

        $modifierB = (strlen($b) == 2) ? substr($b, 1, 1) : "";

    

        if ($substrA == $substrB){

            //figure out plusses and minuses.

            if ($modifierA == "+"){

                return -1;

            } else if ($modifierB == "+"){

                return 1;

            }

        

            if ($modifierA == "-"){

                return 1;

            } else if ($modifierB == '-'){

                return -1;

            }

        } else {

            return strcasecmp($a, $b);

        }

 

    }

   return strcasecmp($a, $b);

}



$grades = array( 

                 "C+" => 13    ,

                "C" => 10     ,

                "D+" => 8     ,

                "B+" => 7     ,

                "C-" => 6     ,

                "A-" => 5     ,

                "F" => 5      ,

                "B" => 4      ,

                "B-" => 4     ,

                "D" => 3      ,

                "D-" => 3     ,

                "A+" => 1

    ); 



uksort($grades, "cmp");

?>



result:  Array

(

    [A+] => 1

    [A-] => 5

    [B+] => 7

    [B] => 4

    [B-] => 4

    [C+] => 13

    [C] => 10

    [C-] => 6

    [D+] => 8

    [D] => 3

    [D-] => 3

    [F] => 5

)

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smcbride at msn dot com ¶

3 years ago

This might be obvious to many, but just to help others that are trying to use this in a class.  Inside a class, you can prefix the function with self:: within the uksort(), and it will work.  Also, if it is in another class that is included, you can prefix it with the class name.

class someclass {
     private function ArraySortCMPIP($a, $b) {
          $a = ip2long($a);
          $b = ip2long($b);

          if ($a == $b) return 0;
          return ($a < $b) ? -1 : 1;
     }

     // Output
     public function PrintResults() {
          uksort($this->someIPAddressArray, 'self::ArraySortCMPIP');
          print_r($this->someIPAddressArray);
     }
}

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jg at delegation dot ca ¶

19 years ago

To sort dates with uksort:

function datediff($a, $b) {
    

$a = date('U',$a);
$b = date('U',$b);

if ($a == $b) $r = 0;
else $r = ($a > $b) ? 1: -1;

return $r;
}

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DimeCadmium ¶

6 years ago

Don't use uksort($array, "strnatcasecmp"); ... use ksort($array, SORT_NATURAL|SORT_FLAG_CASE);

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Jimomighty ¶

19 years ago

...

function cmp($a, $b)
{
   if ($a == $b) {
       return 0;
   }
   return ($a < $b) ? -1 : 1;
}

function uksort_tree ( &$array )
{
    // [PHP5] foreach ( $array as &$value )
    foreach ( $array as $key => $value )
    {
       if ( is_array ( $value ) )
       {
            // [PHP5] uksort_tree ( $value );
           uksort_tree ( $array[$key] );
       }
    }

    uksort( $array, "cmp" );
}

uksort_tree( $myEntryArray );

...

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webmaster at kik-it at N0SP4M dot com ¶

20 years ago

The code below allows you to sort an array_A following array_B keys order, original keys and values remain associated.

<?

//main function
Function SortArrayAKeysLikeArrayBKeys(&$TheArrayToSort){
   uksort($TheArrayToSort,"SortArrayAKeysLikeArrayBKeys_cmp");
}

//the custom compare function
Function SortArrayAKeysLikeArrayBKeys_cmp($a,$b){
  global $TheArrayOrder;
  $PosA=KeyPosInArray($a,$TheArrayOrder);
  $PosB=KeyPosInArray($b,$TheArrayOrder);
  if ($PosA==$PosB){return 0;}else{return ($PosA > $PosB ? 1 : -1);}
}

//where is my key in my array
Function KeyPosInArray($Key,$Array){
   $i=0;
   $Pos=99999999;
   if($Array){
      foreach($Array as $K => $V){
         $i++;
         if($K==$Key){
            $Pos=$i;
            break;
         }
      }
   }
   return $Pos;
}

//the array you want to sort
$AnyArrayToSort['age']='19';
$AnyArrayToSort['ville']='rennes';
$AnyArrayToSort['website']='kik-it.com';
$AnyArrayToSort['region']='bretagne';
$AnyArrayToSort['code_postal']='35200';
$AnyArrayToSort['Nom']='Fred';

//the array with the correct keys/values order
$TheArrayOrder['Nom']='Whatever';
$TheArrayOrder['age']='Anything';
$TheArrayOrder['region']='What u want';
$TheArrayOrder['ville']='Something';
$TheArrayOrder['code_postal']='Nothing';

//before sort
print_r($AnyArrayToSort);    
echo "<br>";
//we sort
SortArrayAKeysLikeArrayBKeys($AnyArrayToSort);
echo "<br>";
//after sort
print_r($AnyArrayToSort);
?>

Will print :

Array ( [age] => 19 [ville] => rennes [website] => kik-it.com [region] => bretagne [code_postal] => 35200 [Nom] => Fred ) 

Array ( [Nom] => Fred [age] => 19 [region] => bretagne [ville] => rennes [code_postal] => 35200 [website] => kik-it.com ) 

The keys not listed in the $TheArrayOrder will appear at the end of your sorted array (only if Key Pos < 99999999 ;o)

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ignatius dot reilly at free dot fr ¶

20 years ago

To use a more complicated comparison function, one can use a callback to a method of an object instance.
For example the following will take an array $arr whose keys are the same as those of $reference, and reorder $arr so that the keys appear in the same order as in $reference.

class kcmp {
    var $reference ;
    function kcmp( $reference ) {
       $this->reference = $reference ; 
    }
    function kcompare( $a, $b ) {
       $keys = array_keys( $this->reference ) ;
       $position_a = array_search( $a, $keys ) ;
       $position_b = array_search( $b, $keys ) ;
       return  $position_a < $position_b ? -1 : 1 ;    
    }
}

$reference = array(
    "k2" => "a2",
    "k3" => "a3",
    "k1" => "a1"
) ;
$arr = array(
    "k1" => "b1",
    "k2" => "b2",
    "k3" => "b3"
) ;
print_r( $arr ) ; 
uksort( $arr, array( new kcmp( $reference ), "kcompare" ) ) ;
print_r( $arr ) ;

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-1

andi at example dot com ¶

8 years ago

I needed to be able to sort a string that contained numbers eg.

"Slot 1 name"
"Slot 2 name"
"Slot 10 name"

using a normal string compare the "Slot 10 name" would appear before "Slot 2 name" so I wrote little function that will compare a string taking numbers in to consideration. There may be a few edge cases that need to be taken in to consideration.

function strCmpWithNumbers( $a, $b) {
  // Split the string in to words.
  $a = explode(' ',$a);
  $b = explode(' ',$b);
  $loop = 0;
  do {
    // Get the first word from each item
    $ta = Utils::gvfa($a, $loop);
    $tb = Utils::gvfa($b, $loop);
    
    if (isset($ta)) {
      if (isset($tb)) {
        if (is_numeric($ta)) {
          if ($ta != $tb) {
            return $ta - $tb;
          }
        } else {
          $val = strcasecmp($ta, $tb);
          if ($val != 0) {
            return $val;
          }
        }
      } else {
        return 1; // a is set but b isn't
      }
    } else {
      return isset($b);
    }
    $loop +=1;
  } while (true);
}

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-5

Anonymous ¶

9 years ago

An associative array with known keys can be easily custom sorted using a switch statement in the callback:

NB ksort can be used beforehand to ensure expected results

ksort($array);

uksort($array, function ($a) {                    
    switch($a) {
        case 'pepperoni':
            return 0;
        case 'beef':
            return 1;
        case 'chicken':
            return 2;
        case 'ham':
            return 3;
        case 'vegetarian':
            return 4;
    }
});

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