How can you prevent the removal of duplicate values when using array functions like array_filter in PHP?

When using array functions like array_filter in PHP, duplicate values may be removed by default because the function only retains unique elements. To prevent this from happening, you can create a custom callback function that specifies the criteria for filtering the array, allowing you to keep duplicate values if needed.

// Example code to prevent removal of duplicate values when using array_filter in PHP

// Sample array with duplicate values
$array = [1, 2, 2, 3, 4, 4, 5];

// Custom callback function to keep all elements
function keepAll($value) {
    return true;
}

// Filter the array using the custom callback function
$filteredArray = array_filter($array, 'keepAll');

// Output the filtered array
print_r($filteredArray);