PHP 7.0.6 Released

    ksort

    (PHP 4, PHP 5, PHP 7)

    ksort — Sort an array by key

    Description

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

    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.

    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

    See Also

    User Contributed Notes

    DavidG
    5 years ago
    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
    7 years ago
    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"
      }
    }
    Anonymous
    2 years ago
    @thegrandoverseer 

    you could also use the build-in php array functions to get exactly what you want to have:

    <?php
            $seed_array     = array('foo'=>'bar', 'someotherkey'=>'whatev', 'bar'=>'baz', 'baz'=>'foo', 'anotherkey'=>'anotherval');
                $keys_array = array('baz', 'foo', 'bar');

                $return_array = array_intersect_key($seed_array, array_flip($keys_array)) + array_diff_key($seed_array, array_flip($keys_array));

    ?>
    delvach at mail dot com
    14 years ago
    A real quick way to do a case-insensitive sort of an array keyed by strings:

    uksort($myArray, "strnatcasecmp");
    sbarnum at mac dot com
    14 years ago
    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.
    thegrandoverseer
    3 years ago
    I wrote this function to sort the keys of an array using an array of keynames, in order.
    <?php
    /**
    * function array_reorder_keys
    * reorder the keys of an array in order of specified keynames; all other nodes not in $keynames will come after last $keyname, in normal array order
    * @param array &$array - the array to reorder
    * @param mixed $keynames - a csv or array of keynames, in the order that keys should be reordered
    */
    function array_reorder_keys(&$array, $keynames){
        if(empty(    $array) || !is_array($array) || empty($keynames)) return;
        if(!    is_array($keynames)) $keynames = explode(',',$keynames);
        if(!empty(    $keynames)) $keynames = array_reverse($keynames);
        foreach(    $keynames as $n){
            if(    array_key_exists($n, $array)){
                    $newarray = array($n=>$array[$n]); //copy the node before unsetting
                    unset($array[$n]); //remove the node
                    $array = $newarray + array_filter($array); //combine copy with filtered array
                }
        }
    }
    $seed_array = array('foo'=>'bar', 'someotherkey'=>'whatev', 'bar'=>'baz', 'baz'=>'foo', 'anotherkey'=>'anotherval');
    array_reorder_keys($seed_array, 'baz,foo,bar'); //returns array('baz'=>'foo', 'foo'=>'bar', 'bar'=>'baz', 'someotherkey'=>'whatev', 'anotherkey'=>'anotherval' );
    ?>
    Anonymous
    2 years ago
    Note that this function will output the given $fields in the order they were added to the data array and not automatically in numerical key order.

    To output in ascending key order, you'll need to ksort the array first (or use appropriate natural order sorting, depending on your keys).

    For example:
    <?php
    $data    [2] = 'C';
    $data[0] = 'A';
    $data[1] = 'B';

    fputcsv($fh, $data); // outputs: "C,A,B"

    ksort($data);
    fputcsv($fh, $data); // outputs: "A,B,C"
    ?>
    ssb45 at cornell dot edu
    10 years ago
    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;
    }
    Anonymous
    14 years ago
    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);
          }
        }
      }
    justin at booleangate dot org
    11 years ago
    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;
    }
    bimal at sanjaal dot com
    1 year ago
    An example of reverse sorting a domain name by its name.

    <?php
    $domains     = array(
            'sub.domain.com',
            'sub2.domain.com',
    );

    foreach(    $domains as $d => $domain)
    {
            $chunks = explode('.', $domain);
            krsort($chunks);

        echo     "\r\n<br>", implode('/', $chunks);
    }

    /**
    * Outputs as:
    *
    * com/domain/sub
    * com/domain/sub2
    */
    ?>
    stephen [ at ] brooksie-net [ dot ] co [ dot ] uk
    3 years ago
    ksort and krsort fail to undestand scientific notation, https://bugs.php.net/bug.php?id=43053, therefore when sorting numeric keys, if the key is of the form 0.00001 php will represent it as 1.0E-5.

    These methods will assume this to be a string and therefore not organise your array as you may expect.

    When using value of this form for array keys use sprintf('%f', 0.00001) to generate the key, for smaller values the precision needs to be included
    e.g. sprintf('%0.10f', 0.00000001)
    jakub dot lopuszanski at nasza-klasa dot pl
    5 years ago
    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!
    centraleffects at yahoo dot com
    2 years ago
    I wrote this function to sort meta_value in wordpress. I tried a lot of array sorting but neither of them work. But this is not suitable for multidimensional array. This is intended only for wordpress meta_value

    The problem is to sort below( the order should be ascending; alphabetically then numerically like A-Z then 0-9):
    500-999 users
    25-49 users
    All Sizes
    1-4 users
    5-9 users
    10-24 users
    250-499 users
    1000-4999
    5000-9999

    The solution:

    function array_sort($arr){
        if(is_array($arr)){
            $numeric = array();
            $string = array();
            foreach($arr as $k => $v)
            {
                if(isset($v["meta_value"])){
                     $str = explode(" ",trim($v["meta_value"]));
                     $firstWord  = explode("-",trim($str[0]));
                 }else{
                     $str = $v;
                     $firstWord  = explode("-",trim($str));
                 }

                $firstWord = $firstWord[0];

                if(is_numeric($firstWord))
                {
                    $numeric[(int)$firstWord] = $v;
                }else{
                    $string[$firstWord] = $v;
                }
                unset($firstWord);
            }
            ksort($string,SORT_STRING);
            ksort($numeric,SORT_NUMERIC);

            return array_merge((array)$string, (array)$numeric);
        }
       

        return false;
    }

    The usage:
    $meta =get_post_meta($post_id,$meta_key);
    $sorted = array_sort($meta);

    The result:
    All Sizes
    1-4 users
    5-9 users
    10-24 users
    25-49 users
    250-499 users
    500-999 users
    1000-4999
    5000-9999
    maik dot riechert at animey dot net
    7 years ago
    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.
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