uksort()

(PHP 4, PHP 5, PHP 7)

使用用户自定义的比较函数对数组中的键名进行排序

说明

uksort()函数将使用用户提供的比较函数对数组中的键名进行排序。如果要排序的数组需要用一种不寻常的标准进行排序，那么应该使用此函数。

If two members compare as equal, their relative order in the sorted array is undefined.

参数

输入的数组。

在第一个参数小于，等于或大于第二个参数时，该比较函数必须相应地返回一个小于，等于或大于 0 的整数。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

Example #1uksort()例子

以上例程会输出：

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

参见

• usort() 使用用户自定义的比较函数对数组中的值进行排序
• 数组排序函数对比

[Editor's note: the following comment may be factually incorrect]
uksort is only usable in the UK 

(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):

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.

sort with collation, to have umlauts correctly:
uksort($retval, array(Collator::create( 'de_DE' ), 'compare'));

Case insensitive without own function:
uksort($array, "strnatcasecmp");

Here is a small and very fast object to handle sorting of multidimentional arrays by a key.

Sample $input_array:
Array
(
  [0] => Array
    (
      [id] => 961
      [uid] => 29
      [gid] => 12
      [parent_id] => 147
      [created] => 20041206105350
      [modified] => 20041206110702
    )
  [1] => Array
    (
      [id] => 41
      [uid] => 29
      [gid] => 12
      [parent_id] => 153
      [created] => 20041025154009
      [modified] => 20041206105532
    )
  [2] => Array
    (
      [id] => 703
      [uid] => 29
      [gid] => 12
      [parent_id] => 419
      [created] => 20041025154132
      [modified] => 20041027150259
    )
Example of usage:

The result array will be:
Array
(
  [0] => Array
    (
      [id] => 703
      [uid] => 29
      [gid] => 12
      [parent_id] => 419
      [created] => 20041025154132
      [modified] => 20041027150259
    )
  [1] => Array
    (
      [id] => 41
      [uid] => 29
      [gid] => 12
      [parent_id] => 153
      [created] => 20041025154009
      [modified] => 20041206105532
    )
  [2] => Array
    (
      [id] => 961
      [uid] => 29
      [gid] => 12
      [parent_id] => 147
      [created] => 20041206105350
      [modified] => 20041206110702
    )

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="aAbBcCčČ..."; // longer normally & without that html entities
  $default = strlen($a) - strlen($b);
  $minlen = strlen($a) 
The code below allows you to sort an array_A following array_B keys order, original keys and values remain associated.

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 $TheArrayOrder will appear at the end of your sorted array (only if Key Pos 
One remark regarding array_sorter class.
It won't work correctly with eg. dates from mysql like 20041206105350, cause you can't convert such number into integer. To fix it remove intval() from the code. If the variable is a number it will work without converting this to int anyways. Here is the fix. 
To sort dates with uksort:
function datediff($a, $b) {
  
$a = date('U',$a);
$b = date('U',$b);
if ($a == $b) $r = 0;
else $r = ($a > $b) ? 1: -1;
return $r;
}
need a case insensitive sort by key function? i did and couldn find it, so: 
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.

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
)
Don't use uksort($array, "strnatcasecmp"); ... use ksort($array, SORT_NATURAL|SORT_FLAG_CASE);
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);
  }
  $loop +=1;
 } while (true);
}
An associative array with known keys can be easily custom sorted using a switch statement in the callback:
NB ksort can be used beforehand to ensure expected results
ksort($array);
uksort($array, function ($a) {          
  switch($a) {
    case 'pepperoni':
      return 0;
    case 'beef':
      return 1;
    case 'chicken':
      return 2;
    case 'ham':
      return 3;
    case 'vegetarian':
      return 4;
  }
});
...
function cmp($a, $b)
{
  if ($a == $b) {
    return 0;
  }
  return ($a  $value )
  {
    if ( is_array ( $value ) )
    {
      // [PHP5] uksort_tree ( $value );
      uksort_tree ( $array[$key] );
    }
  }
  uksort( $array, "cmp" );
}
uksort_tree( $myEntryArray );
...
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  "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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