source: branches/rsr.v5.1.1/web/punbb/include/utf8/str_split.php

<?php

/**
* @version $Id: str_split.php,v 1.1 2006/02/25 13:50:17 harryf Exp $
* @package utf8
* @subpackage strings
*/

/**
* UTF-8 aware alternative to str_split
* Convert a string to an array
* Note: requires utf8_strlen to be loaded
* @param string UTF-8 encoded
* @param int number to characters to split string by
* @return string characters in string reverses
* @see http://www.php.net/str_split
* @see utf8_strlen
* @package utf8
* @subpackage strings
*/
function utf8_str_split($str, $split_len=1)
{
        if (!preg_match('/^[0-9]+$/',$split_len) || $split_len < 1)
                return false;

        $len = utf8_strlen($str);
        if ($len <= $split_len)
                return array($str);

        preg_match_all('/.{'.$split_len.'}|[^\x00]{1,'.$split_len.'}$/us', $str, $ar);

        return $ar[0];
}