ksort

(PHP 4, PHP 5)

ksort — Sort an array by key

Description

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

Sorts an array by key, maintaining key to data correlations. This is useful mainly for associative arrays.

Parameters

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

Return Values

Returns TRUE on success or FALSE on failure.

ChangeLog

Version	Description
4.0.0	The optional `sort_flags` parameter was added.

Examples

Example #1 ksort() example


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

The above example will output:

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


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 08:58


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 06:04


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
07-May-2004 12:08


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 12:58


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

10-Mar-2002 12:09


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
07-Nov-2001 06:29


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





uksort($myArray, "strnatcasecmp");

sbarnum at mac dot com
20-Oct-2001 07:54


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.

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Last updated: Fri, 18 Jul 2008