PHP Array Exercises : Change the array values to upper or lower case

Last update on May 30 2025 13:14:56 (UTC/GMT +8 hours)

12. Change Array Values to Lower and Upper Case

Write a PHP function to change the following array's all values to upper or lower case.

Sample arrays :
$Color = array('A' => 'Blue', 'B' => 'Green', 'c' => 'Red');

Sample Solution:

PHP Code:

<?php
// Define a function named 'array_change_value_case' that changes the case of array values
function array_change_value_case($input, $ucase)
{
    // Store the desired case (CASE_UPPER or CASE_LOWER) in the variable $case
    $case = $ucase;

    // Initialize an empty array to store the new values
    $narray = array();

    // Check if the input is not an array
    if (!is_array($input))
    {
        // If not an array, return an empty array
        return $narray;
    }

    // Iterate through the input array
    foreach ($input as $key => $value)
    {
        // Check if the current value is an array
        if (is_array($value))
        {
            // If it's an array, recursively call the function on the sub-array
            $narray[$key] = array_change_value_case($value, $case);
            // Continue to the next iteration
            continue;
        }

        // Change the case of the current value based on the specified case
        $narray[$key] = ($case == CASE_UPPER ? strtoupper($value) : strtolower($value));
    }

    // Return the new array with changed case values
    return $narray;
}

// Define an associative array $Color with keys 'A', 'B', and 'c'
$Color = array('A' => 'Blue', 'B' => 'Green', 'c' => 'Red');

// Output a message indicating the start of the section for the actual array
echo 'Actual array ';

// Display the original array $Color
print_r($Color);

// Output a message indicating that values are in lower case
echo 'Values are in lower case.';

// Call the array_change_value_case function with CASE_LOWER and display the result
$myColor = array_change_value_case($Color, CASE_LOWER);
print_r($myColor);

// Output a message indicating that values are in upper case
echo 'Values are in upper case.';

// Call the array_change_value_case function with CASE_UPPER and display the result
$myColor = array_change_value_case($Color, CASE_UPPER);
print_r($myColor);
?>

Output:

Actual array Array                                          
(                                                           
    [A] => Blue                                             
    [B] => Green                                            
    [c] => Red                                              
)                                                           
Values are in lower case.Array                              
(                                                           
    [A] => blue                                             
    [B] => green                                            
    [c] => red                                              
)                                                           
Values are in upper case.Array                              
(                                                           
    [A] => BLUE                                             
    [B] => GREEN                                            
    [c] => RED                                              
)

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP function to convert all values in an associative array to lowercase using array_map and display the result.
Write a PHP script to iterate over an array and toggle each value between upper and lower case, then output both versions.
Write a PHP program to compare the results of converting an array’s values to lowercase versus uppercase, then display both arrays side-by-side.
Write a PHP script to implement a function that accepts an array and a desired case ("upper" or "lower") and returns the transformed array.

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