PHP Conference Nagoya 2025

    array_change_key_case

    (PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

    array_change_key_case — Cambia a mayúsculas o minúsculas todas las claves en un array

    Descripción

    array_change_key_case(array $array, int $case = CASE_LOWER): array

    Devuelve un array a partir de array con todas las claves convertidas a minúsculas o mayúsculas. Los índices numerados son dejados como están.

    Parámetros

    array

    Array para trabajar en

    case

    Entre CASE_UPPER o CASE_LOWER (por defecto)

    Valores devueltos

    Devuelve un array con sus keys converitdas en minúsculas o mayúsculas, o false si array no es una matriz.

    Errores/Excepciones

    Lanza un E_WARNING si array no es un array.

    Ejemplos

    Ejemplo #1 Ejemplo de array_change_key_case()

    <?php
    $input_array     = array("FirSt" => 1, "SecOnd" => 4);
    print_r(array_change_key_case($input_array, CASE_UPPER));
    ?>

    El resultado del ejemplo sería:

    Array
(
    [FIRST] => 1
    [SECOND] => 4
)

    Notas

    Nota:

    Si un array tiene índices que queden iguales una vez se aplique ésta función (ej. "claVE" y "cLAve"), el valor que esté después en la matriz anulará los otros índices.

    Found A Problem?

    Learn How To Improve This Page • Submit a Pull Request • Report a Bug
    ＋add a note

    User Contributed Notes 12 notes

    up
    27
    qeremy [atta] gmail [dotta] com
    12 years ago
    Unicode example;

    <?php
    function array_change_key_case_unicode($arr, $c = CASE_LOWER) {
    $c = ($c == CASE_LOWER) ? MB_CASE_LOWER : MB_CASE_UPPER;
    foreach (    $arr as $k => $v) {
    $ret[mb_convert_case($k, $c, "UTF-8")] = $v;
    }
    return     $ret;
    }

    $arr = array("FirSt" => 1, "yağ" => "Oil", "şekER" => "sugar");
    print_r(array_change_key_case($arr, CASE_UPPER));
    print_r(array_change_key_case_unicode($arr, CASE_UPPER));
    ?>

    Array
    (
    [FIRST] => 1
    [YAğ] => Oil
    [şEKER] => sugar
    )
    Array
    (
    [FIRST] => 1
    [YAĞ] => Oil
    [ŞEKER] => sugar
    )
    up
    12
    xsaero00
    10 years ago
    Here is the most compact way to lower case keys in a multidimensional array

    function array_change_key_case_recursive($arr)
    {
    return array_map(function($item){
    if(is_array($item))
    $item = array_change_key_case_recursive($item);
    return $item;
    },array_change_key_case($arr));
    }
    up
    8
    zhangxuejiang
    5 years ago
    I improve the array_change_key_case_recursive function ,let it can lowercase or uppercase keys

    function array_change_key_case_recursive($arr, $case = CASE_LOWER)
    {
    return array_map(function($item) use($case) {
    if(is_array($item))
    $item = array_change_key_case_recursive($item, $case);
    return $item;
    },array_change_key_case($arr, $case));
    }
    up
    2
    msegit post pl
    3 years ago
    Improved multidimensional unicode func (after qeremy):
    <?php
    function array_change_key_case_unicode_recurs($arr, $c = CASE_LOWER) {
    foreach (    $arr as $k => $v) {
    $ret[mb_convert_case($k, (($c === CASE_LOWER) ? MB_CASE_LOWER : MB_CASE_UPPER), "UTF-8")] = (is_array($v) ? array_change_key_case_unicode_recurs($v, $c) : $v );
    }
    return     $ret;
    }

    $arr = array("FirSt" => 1, "ZażóŁć gęŚlą jaŹń" => array("yağ" => "Oil", "şekER" => "sugar") );
    print_r(array_change_key_case($arr, CASE_UPPER));
    print_r(array_change_key_case_unicode_recurs($arr, CASE_UPPER));
    ?>

    Array
    (
    [FIRST] => 1
    [ZAżóŁć GęŚLą JAŹń] => Array
    (
    [yağ] => Oil
    [şekER] => sugar
    )
    )
    Array
    (
    [FIRST] => 1
    [ZAŻÓŁĆ GĘŚLĄ JAŹŃ] => Array
    (
    [YAĞ] => Oil
    [ŞEKER] => sugar
    )
    )
    up
    -2
    gsoft
    1 year ago
    //Array key case change recursively (Unicode):

    <?php
    function array_key_case($data,$case=FALSE)
    {
    $ret=array();
    if (     is_array($data) )
    foreach (    $data as $idx => $val)
    $ret[$case ? mb_strtoupper($idx) : mb_strtolower($idx)]=array_key_case($val,$case);
    else
    $ret=$data;
    return     $ret;
    }
    up
    0
    andreas dot schuhmacher87 at googlemail dot com
    16 years ago
    multibyte and multi-dimensional-array support, have fun!

    <?php
    define    ('ARRAY_KEY_FC_LOWERCASE', 25); //FOO => fOO
    define('ARRAY_KEY_FC_UPPERCASE', 20); //foo => Foo
    define('ARRAY_KEY_UPPERCASE', 15); //foo => FOO
    define('ARRAY_KEY_LOWERCASE', 10); //FOO => foo
    define('ARRAY_KEY_USE_MULTIBYTE', true); //use mutlibyte functions

    /**
    * change the case of array-keys
    *
    * use: array_change_key_case_ext(array('foo' => 1, 'bar' => 2), ARRAY_KEY_UPPERCASE);
    * result: array('FOO' => 1, 'BAR' => 2)
    *
    * @param array
    * @param int
    * @return array
    */
    function array_change_key_case_ext(array $array, $case = 10, $useMB = false, $mbEnc = 'UTF-8') {
    $newArray = array();

    //for more speed define the runtime created functions in the global namespace

    //get function
    if($useMB === false) {
    $function = 'strToUpper'; //default
    switch($case) {
    //first-char-to-lowercase
    case 25:
    //maybee lcfirst is not callable
    if(!function_exists('lcfirst'))
    $function = create_function('$input', '
    return strToLower($input[0]) . substr($input, 1, (strLen($input) - 1));
    '    );
    else     $function = 'lcfirst';
    break;

    //first-char-to-uppercase
    case 20:
    $function = 'ucfirst';
    break;

    //lowercase
    case 10:
    $function = 'strToLower';
    }
    } else {
    //create functions for multibyte support
    switch($case) {
    //first-char-to-lowercase
    case 25:
    $function = create_function('$input', '
    return mb_strToLower(mb_substr($input, 0, 1, \''     . $mbEnc . '\')) .
    mb_substr($input, 1, (mb_strlen($input, \''     . $mbEnc . '\') - 1), \'' . $mbEnc . '\');
    '    );

    break;

    //first-char-to-uppercase
    case 20:
    $function = create_function('$input', '
    return mb_strToUpper(mb_substr($input, 0, 1, \''     . $mbEnc . '\')) .
    mb_substr($input, 1, (mb_strlen($input, \''     . $mbEnc . '\') - 1), \'' . $mbEnc . '\');
    '    );

    break;

    //uppercase
    case 15:
    $function = create_function('$input', '
    return mb_strToUpper($input, \''     . $mbEnc . '\');
    '    );
    break;

    //lowercase
    default: //case 10:
    $function = create_function('$input', '
    return mb_strToLower($input, \''     . $mbEnc . '\');
    '    );
    }
    }

    //loop array
    foreach($array as $key => $value) {
    if(    is_array($value)) //$value is an array, handle keys too
    $newArray[$function($key)] = array_change_key_case_ex($value, $case, $useMB);
    elseif(    is_string($key))
    $newArray[$function($key)] = $value;
    else     $newArray[$key] = $value; //$key is not a string
    } //end loop

    return $newArray;
    }
    ?>
    up
    -1
    shaman_master at list dot ru
    5 years ago
    <?php
    /**
    * Convert keys in an array.
    *
    * @param array $array Source data
    * @param callable $callback Function name (strtolower, strtoupper, ucfirst, lcfirst, ucwords)
    * @return array
    */
    function array_convert_key_case(array $array, callable $callback = 'strtolower')
    {
    return     array_combine(
    array_map($callback, array_keys($array)),
    array_values($array)
    );
    }
    ?>
    up
    -2
    NetPanther
    12 years ago
    Use this to capitalize first letter of all array keys:

    <?php

    function ucfirstKeys(&$data)
    {
    foreach (    $data as $key => $value)
    {
    // Convert key
    $newKey = ucfirst($key);

    // Change key if needed
    if ($newKey != $key)
    {
    unset(    $data[$key]);
    $data[$newKey] = $value;
    }

    // Handle nested arrays
    if (is_array($value))
    {
    ucfirstKeys($data[$key]);
    }
    }
    }

    $test = array('foo' => 'bar', 'moreFoo' => array('more' => 'foo'));
    ucfirstKeys($test);
    print_r($test);

    ?>

    Result:
    Array ( [MoreFoo] => Array ( [More] => foo ) [Foo] => bar )
    up
    -3
    anon at ymous dot com
    16 years ago
    Below is a recursive version of this function.

    <?php
    /**
    * A recursive array_change_key_case function.
    * @param array $input
    * @param integer $case
    */
    function array_change_key_case_recursive($input, $case = null){
    if(!    is_array($input)){
    trigger_error("Invalid input array '{$array}'",E_USER_NOTICE); exit;
    }
    // CASE_UPPER|CASE_LOWER
    if(null === $case){
    $case = CASE_LOWER;
    }
    if(!    in_array($case, array(CASE_UPPER, CASE_LOWER))){
    trigger_error("Case parameter '{$case}' is invalid.", E_USER_NOTICE); exit;
    }
    $input = array_change_key_case($input, $case);
    foreach(    $input as $key=>$array){
    if(    is_array($array)){
    $input[$key] = array_change_key_case_recursive($array, $case);
    }
    }
    return     $input;
    }
    ?>
    up
    -3
    cm at gameswelt dot de
    17 years ago
    I just changed the code a little bit so you havent got a code that repeats itself.

    <?php

    function array_change_key_case_secure($array = array(), $case = CASE_UPPER){
    $secure = array();
    $functionWrap = array(CASE_UPPER => 'strtoupper',
    CASE_LOWER => 'strtolower');

    foreach(    $array as $key => $val){
    if(isset(    $functionWrap[$key])){
    $key = $functionWrap[$case]($key);
    $secure[$key][] = $val;
    } else {
    die(    'Not a known Type');
    }
    }

    foreach(    $secure as $key => $val){
    if(    count($secure[$key]) == 1){
    $secure[$key] = $val[0];
    }
    }

    return     $secure;
    }

    $myArray = array('A' => 'Hello',
    'B' => 'World',
    'a' => 'how are you?');

    print_r($myArray);
    $myArray = array_change_key_case_secure($myArray);
    print_r($myArray);

    /*
    Array
    (
    [A] => Hello
    [B] => World
    [a] => how are you?
    )
    Array
    (
    [A] => Array
    (
    [0] => Hello
    [1] => how are you?
    )

    [B] => World
    )
    */
    up
    -5
    john at doe dot com
    17 years ago
    <?php
    function array_change_value_case($input, $case = CASE_LOWER)
    {
    $aRet = array();

    if (!    is_array($input))
    {
    return     $aRet;
    }

    foreach (    $input as $key => $value)
    {
    if (    is_array($value))
    {
    $aRet[$key] = array_change_value_case($value, $case);
    continue;
    }

    $aRet[$key] = ($case == CASE_UPPER ? strtoupper($value) : strtolower($value));
    }

    return     $aRet;
    }
    ?>
    up
    -2
    wendri dot net at gmail dot com
    2 years ago
    Array of partitions with always the same number of sub-array indexes.

    <?php

    function partitionFixedSubArray($array, $length, $empty_space)
    {
    $result = [];

    if (     sizeof($array) ) {

    $result = array_chunk($array, $length);
    $last_array_count = sizeof(end($result));

    if (    $last_array_count < $length) {

    for (    $i = $last_array_count; $i < $length; $i++) {
    array_push($result[key($result)], $empty_space);
    }
    }
    }

    return     $result;
    }

    $employees = [
    "Paidi",
    "Paijo",
    "Darno",
    "Kusnan",
    "Mukidi",
    "Sarno",
    "Nurdin",
    "Parmen",
    "Sukinah",
    "Sartini",
    "Sukijan",
    "Yono",
    "Supoyo"
    ];

    echo     "<pre>";
    print_r(partitionFixedSubArray($employees, 5, "empty space"));
    echo     "</pre>";

    ?>

    Output:
    Array
    (
    [0] => Array
    (
    [0] => Paidi
    [1] => Paijo
    [2] => Darno
    [3] => Kusnan
    [4] => Mukidi
    )

    [1] => Array
    (
    [0] => Sarno
    [1] => Nurdin
    [2] => Parmen
    [3] => Sukinah
    [4] => Sartini
    )

    [2] => Array
    (
    [0] => Sukijan
    [1] => Yono
    [2] => Supoyo
    [3] => empty space
    [4] => empty space
    )

    )
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