PHP | array_change_key_case() Function

The array_change_key_case() function is an inbuilt function in PHP and is used to change case of all of the keys in a given array either to lower case or upper case.

Syntax:

array array_change_key_case(in_array, convert_case)

Parameters: This function accepts two parameters out of which one is mandatory and the other is optional. The two parameters are described below:



  1. in_array (mandatory): This parameter refers to the array whose key’s case is needed to be changed.
  2. convert_case (optional): This is an optional parameter and refers to the ‘case’ in which we need to convert the keys of the array. This can take two values, either CASE_UPPER or CASE_LOWER. CASE_UPPER value determines the uppercase and CASE_LOWER determines lowercase. If the convert_case parameter is not passed then it’s default value is taken which is CASE_LOWER.

Note: If the second parameter is ignored then by default the keys of array will get converted to lowercase.

Return Type: The function returns an array with the changed case of the key, either to lowercase or to upper case.

Let us now look at some programs to get a better understanding of working of array_change_key_case() function.

  • Below program converts the case of keys to uppercase:

    filter_none

    edit
    close

    play_arrow

    link
    brightness_4
    code

    <?php
      
    // PHP code to illustrate array_change_key_case()
    // Both the parameters are passed
    function change_case($in_array){
        return(array_change_key_case($in_array, CASE_UPPER));
    }
      
    // Driver Code
    $array = array("Aakash" => 90, "RagHav" => 80, 
                   "SiTa" => 95, "rohan" => 85, "RISHAV" => 70);
    print_r(change_case($array));
      
    ?>

    chevron_right

    
    

    Output:

    Array
    (
        [AAKASH] => 90
        [RAGHAV] => 80
        [SITA] => 95
        [ROHAN] => 85
        [RISHAV] => 70
    )
    
  • If we ignore the second parameter convert_case in the function array_change_key_case() then the keys will be converted to lowercase. Below program illustrates this:

    filter_none

    edit
    close

    play_arrow

    link
    brightness_4
    code

    <?php
      
    // PHP code to illustrate array_change_key_case()
    // Second parameter is ignored
    function change_case($in_array){
        return(array_change_key_case($in_array));
    }
      
    // Driver Code
    $array = array("Aakash" => 90, "RagHav" => 80, 
                   "SiTa" => 95, "rohan" => 85, "RISHAV" => 70);
    print_r(change_case($array));
      
    ?>

    chevron_right

    
    

    Output:

    Array
    (
        [aakash] => 90
        [raghav] => 80
        [sita] => 95
        [rohan] => 85
        [rishav] => 70
    )
    
  • If we don’t pass an array to the function then PHP_Warning is popped up, but the program works and No Output is generated. Below program illustrates this

    filter_none

    edit
    close

    play_arrow

    link
    brightness_4
    code

    <?php
      
    // PHP code to illustrate array_change_key_case()
    // NO parameter is passed
    function change_case($in_array){
        return(array_change_key_case());
    }
      
    // Driver Code
    $array = array("Aakash" => 90, "RagHav" => 80, 
                   "SiTa" => 95, "rohan" => 85, "RISHAV" => 70);
    print_r(change_case($array));
      
    ?>

    chevron_right

    
    

    Output:

    No Output
    

    Warning:

    PHP Warning:  array_change_key_case() expects at least 1 parameter, 
    0 given in /home/7d540b2d77cbbfa46af4fb8798fb5e79.php on line 5


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.




Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.