Description:
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While working recently on a project that involves JSON, I saw that it might be necessary to make sure that a an array's keys are in utf-8 encoding for when I pass it to the JSON encoder, since JSON expects stuff to be in utf-8. One possible way to do this with PHP's existing array functions is with array_combine(), and converting all the elements in the keys array to utf-8 before combining it with the elements array, but this seems like it could become more tedious with nested arrays. I tried using foreach($array as &$key => $val) to convert the key's encoding in each iteration, but got an error saying "Fatal error: Key element cannot be a reference". So I wrote my own function (included below).

Why isn't there an array_key_walk_recursive() function, or something of the kind? A function that would let you apply a callback to all keys in an array. Or, let you use foreach with a referenced key as I mentioned.

Reproduce code:
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<?php
function array_convert_key_encoding($array) {
    $encoded_array = array();
    foreach($array as $key => $val) {
        if(is_string($key) && is_array($val)) {
            $encoded_array[utf8_encode($key)] = array_convert_key_encoding($val);
        }
        else if(is_string($key)) {
            $encoded_array[utf8_encode($key)] = $val;
        }
        else {
            $encoded_array[$key] = $val;
        }
    }
    return $encoded_array;
}
?>