数组 函数
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ksort

(PHP 4, PHP 5)

ksort — 对数组按照键名排序

说明

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

对数组按照键名排序，保留键名到数据的关联。本函数主要用于关联数组。

成功时返回 TRUE， 或者在失败时返回 FALSE.

Example #1 ksort() 例子

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

以上例程会输出：

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

可以用可选参数 sort_flags 改变排序的行为，详情见 sort()。

参见 asort()，arsort()，krsort()，uksort()，sort()，natsort() 和 rsort()。

Note:

第二个参数是 PHP 4 新加的。

参数

array

The input array.

sort_flags

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

返回值

成功时返回 TRUE， 或者在失败时返回 FALSE.

范例

Example #2 ksort() example

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

以上例程会输出：

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

参见

数组 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 对数组按照键名排序

用户评论:

Haprog (15-Aug-2011 01:50)

Here is a function to recursively sort multidimentional arrays by key:

<?php
function deep_ksort(&$arr) {
    ksort($arr);
    foreach ($arr as &$a) {
        if (is_array($a) && !empty($a)) {
            deep_ksort($a);
        }
    }
}
?>

jakub dot lopuszanski at nasza-klasa dot pl (14-Apr-2011 04:48)

Note that ksort will NOT help you much if numeric and string keys are mixed together.
<?php
$t = array(
  "a"=>"A",
  0=>"A",
  "b"=>"A",
  1=>"A"
);
var_dump($t);
ksort($t);
var_dump($t);
?>

produces (on PHP 5.3.6-4 with Suhosin-Patch) :

array(4) {
  ["a"]=>
  string(1) "A"
  [0]=>
  string(1) "A"
  ["b"]=>
  string(1) "A"
  [1]=>
  string(1) "A"
}

array(4) {
  ["b"]=>
  string(1) "A"
  [0]=>
  string(1) "A"
  ["a"]=>
  string(1) "A"
  [1]=>
  string(1) "A"
}

note that the second array should be sorted by keys, but is even more messed up than the first one!

DavidG (17-Jun-2010 02:47)

A nice way to do sorting of a key on a multi-dimensional array without having to know what keys you have in the array first:

<?php
$people = array(
array("name"=>"Bob","age"=>8,"colour"=>"red"),
array("name"=>"Greg","age"=>12,"colour"=>"blue"),
array("name"=>"Andy","age"=>5,"colour"=>"purple"));

var_dump($people);

$sortArray = array();

foreach($people as $person){
    foreach($person as $key=>$value){
        if(!isset($sortArray[$key])){
            $sortArray[$key] = array();
        }
        $sortArray[$key][] = $value;
    }
}

$orderby = "name"; //change this to whatever key you want from the array

array_multisort($sortArray[$orderby],SORT_DESC,$people);

var_dump($people);
?>

Output from first var_dump:

[0]=&gt;
  array(3) {
    ["name"]=&gt;
    string(3) "Bob"
    ["age"]=&gt;
    int(8)
    ["colour"]=&gt;
    string(3) "red"
  }
  [1]=&gt;
  array(3) {
    ["name"]=&gt;

    string(4) "Greg"
    ["age"]=&gt;
    int(12)
    ["colour"]=&gt;
    string(4) "blue"
  }
  [2]=&gt;
  array(3) {
    ["name"]=&gt;
    string(4) "Andy"
    ["age"]=&gt;
    int(5)
    ["colour"]=&gt;

    string(6) "purple"
  }
}

Output from 2nd var_dump:

array(3) {
  [0]=&gt;
  array(3) {
    ["name"]=&gt;
    string(4) "Greg"
    ["age"]=&gt;
    int(12)
    ["colour"]=&gt;
    string(4) "blue"
  }
  [1]=&gt;
  array(3) {
    ["name"]=&gt;

    string(3) "Bob"
    ["age"]=&gt;
    int(8)
    ["colour"]=&gt;
    string(3) "red"
  }
  [2]=&gt;
  array(3) {
    ["name"]=&gt;
    string(4) "Andy"
    ["age"]=&gt;
    int(5)
    ["colour"]=&gt;

    string(6) "purple"
  }

There's no checking on whether your array keys exist, or the array data you are searching on is actually there, but easy enough to add.

serpro at gmail dot com (13-Mar-2009 10:02)

Here is a function to sort an array by the key of his sub-array.

<?php

function sksort(&$array, $subkey="id", $sort_ascending=false) {

    if (count($array))
        $temp_array[key($array)] = array_shift($array);

    foreach($array as $key => $val){
        $offset = 0;
        $found = false;
        foreach($temp_array as $tmp_key => $tmp_val)
        {
            if(!$found and strtolower($val[$subkey]) > strtolower($tmp_val[$subkey]))
            {
                $temp_array = array_merge(    (array)array_slice($temp_array,0,$offset),
                                            array($key => $val),
                                            array_slice($temp_array,$offset)
                                          );
                $found = true;
            }
            $offset++;
        }
        if(!$found) $temp_array = array_merge($temp_array, array($key => $val));
    }

    if ($sort_ascending) $array = array_reverse($temp_array);

    else $array = $temp_array;
}

?>

Example
<?php
$info = array("peter" => array("age" => 21,
                                           "gender" => "male"
                                           ),
                   "john"  => array("age" => 19,
                                           "gender" => "male"
                                           ),
                   "mary" => array("age" => 20,
                                           "gender" => "female"
                                          )
                  );

sksort($info, "age");
var_dump($info);

sksort($info, "age", true);
var_dump($ifno);
?>

This will be the output of the example:

/*DESCENDING SORT*/
array(3) {
  ["peter"]=>
  array(2) {
    ["age"]=>
    int(21)
    ["gender"]=>
    string(4) "male"
  }
  ["mary"]=>
  array(2) {
    ["age"]=>
    int(20)
    ["gender"]=>
    string(6) "female"
  }
  ["john"]=>
  array(2) {
    ["age"]=>
    int(19)
    ["gender"]=>
    string(4) "male"
  }
}

/*ASCENDING SORT*/
array(3) {
  ["john"]=>
  array(2) {
    ["age"]=>
    int(19)
    ["gender"]=>
    string(4) "male"
  }
  ["mary"]=>
  array(2) {
    ["age"]=>
    int(20)
    ["gender"]=>
    string(6) "female"
  }
  ["peter"]=>
  array(2) {
    ["age"]=>
    int(21)
    ["gender"]=>
    string(4) "male"
  }
}

maik dot riechert at animey dot net (12-Aug-2008 07:32)

Be careful when using ksort for mixed type keys!!

$a = array(
    'first' => true,
    0       => 'sally',
);

$b = array(
    0       => 'sally',
    'first' => true,
);

ksort($a);
ksort($b);
var_dump($a);
var_dump($b);

Output is:
array(
    0 => 'sally',
    'first' => true,
)

array(
    'first' => true,
    0 => 'sally',
)

If you want same results for both arrays, use:

ksort($a, SORT_STRING);

The reason for that lays in the compare mechanism which would normally just typecast 'first' to an integer or 0 to a string when comparing it to each other. So you have to use SORT_STRING, otherwise you would lose information when 'first' is converted to int.

(06-Nov-2006 01:26)

Why not just use built-in PHP functions? You can do an in-place natural sort by keys with:

uksort($array, 'strnatcasecmp');

richard dot quadling at bandvulc dot co dot uk (24-Oct-2005 09:10)

Just to complete the comments made by ssb45.

If the supplied array is an empty array, the value returned is NOT an array.

All that is required is to pre-initialize the result.

function natksort(&$aToBeSorted)
    {
    $aResult = array();
    $aKeys = array_keys($aToBeSorted);
    natcasesort($aKeys);
    foreach ($aKeys as $sKey)
        {
        $aResult[$sKey] = $aToBeSorted[$sKey];
        }
    $aToBeSorted = $aResult;
    return True;
    }

ssb45 at cornell dot edu (30-Jun-2005 12:58)

The function that justin at booleangate dot org provides works well, but be aware that it is not a drop-in replacement for ksort as is.  While ksort sorts the array by reference and returns a status boolean, natksort returns the sorted array, leaving the original untouched.  Thus, you must use this syntax:

$array = natksort($array);

If you want to use the more natural syntax:

$status = natksort($array);

Then use this modified version:

function natksort(&$array) {
    $keys = array_keys($array);
    natcasesort($keys);

    foreach ($keys as $k) {
        $new_array[$k] = $array[$k];
    }

    $array = $new_array;
    return true;
}

justin at booleangate dot org (18-Jan-2005 09:04)

Here's a handy function for natural order sorting on keys.

function natksort($array) {
  // Like ksort but uses natural sort instead
  $keys = array_keys($array);
  natsort($keys);

  foreach ($keys as $k)
    $new_array[$k] = $array[$k];

  return $new_array;
}

yaroukh at email dot cz (06-May-2004 04:08)

I believe documentation should mention which of array-functions do reset the internal pointer; this one does so ...

pedromartinez at alquimiapaginas dot com (29-Nov-2003 03:58)

A list of directories can be listed sorted by date (newer first) with this script. This is usefull if the directories contain (for example) pictures and you want the newer to appear first.

$maindir = "." ;
$mydir = opendir($maindir) ;

// SORT
$directorios = array();
while (false !== ($fn = readdir($mydir)))
{
    if (is_dir($fn) && $fn != "." && $fn != "..")
    {
        $directory = getcwd()."/$fn";
        $key = date("Y\-m\-d\-His ", filectime($directory));
        $directorios[$key] = $directory;
    }
}

ksort($directorios);
$cronosdir = array();
$cronosdir = array_reverse($directorios);

while (list($key, $directory) = each($cronosdir)) {
    echo "$key = $directory<bR>";
}

Pedro

(09-Mar-2002 03:09)

here 2 functions to ksort/uksort an array and all its member arrays

function tksort(&$array)
  {
  ksort($array);
  foreach(array_keys($array) as $k)
    {
    if(gettype($array[$k])=="array")
      {
      tksort($array[$k]);
      }
    }
  }

function utksort(&$array, $function)
  {
  uksort($array, $function);
  foreach(array_keys($array) as $k)
    {
    if(gettype($array[$k])=="array")
      {
      utksort($array[$k], $function);
      }
    }
  }

delvach at mail dot com (06-Nov-2001 09:29)

A real quick way to do a case-insensitive sort of an array keyed by strings:

uksort($myArray, "strnatcasecmp");

sbarnum at mac dot com (19-Oct-2001 11:54)

ksort on an array with negative integers as keys yields some odd results.  Not sure if this is a bad idea (negative key values) or what.