Multibyte str_split(). The mbstring library PHP < 7.x doesn’t come with a multibyte equivalent of str_split(). This function behaves like mb_str_split in PHP > 7.x

mb_str_split.php

<?php
function mb_str_split($string, $length = 1, $encoding = NULL) {
    if (!is_null($string) && !is_scalar($string)) {
        $type = gettype($string) === 'object' ? get_class($string) : gettype($string);
        throw new \Exception(sprintf('mb_str_split(): Argument #1 ($string) must be of type string, %s given', $type));
    }
    if ((!is_null($length) && !is_numeric($length)) || $length === '') {
        $type = gettype($length) === 'object' ? get_class($length) : gettype($length);
        throw new \Exception(sprintf('mb_str_split(): Argument #2 ($string) must be of type int, %s given', $type));
    }
    if ((int)$length < 1) {
        throw new \Exception('mb_str_split(): Argument #2 ($length) must be greater than 0');
    }
    if ($encoding === NULL) {
        $encoding = mb_internal_encoding();
    }
    $array = array();
    $n = mb_strlen($string, $encoding);
    for ($i = 0; $i < $n; $i += $length) {
        $array []= mb_substr($string, $i, $length, $encoding);
    }
    // PHP v5 str_split behaviour
    // if (!$array) {
    //     return array('');
    // }
    return $array;
}