moriyoshi sama, what do you think about this FR?  thanks

I have the impression that mb_split() pretty much does the expected work, unless 
we really want a counterpart of every byte-wise string function in mbstring...

@moriyoshi

array str_split (string $string[, int $split_length = 1 ])
Converts a string to an array. 

array mb_split (string $pattern, string $string [, int $limit = -1 ])
Split a multibyte string using regular expression pattern and returns the result as an array. 


Performance-wise, I wouldn't say mb_split (using a regular expression) is the same as str_split? Also, I'm curious how to call mb_split with a proper regexp so that it simulates str_split?

Example:
<?php
		function mb_str_split($str, $length = 1)
		{
		  if ($length < 1) return FALSE;
		  $result = array();
		  for ($i = 0; $i < mb_strlen($str); $i += $length) {
			$result[] = mb_substr($str, $i, $length);
		  }
		  return $result;
		}

mb_internal_encoding('UTF-8'); 
mb_regex_encoding('UTF-8');  

$test='әӘ火车票abc';
print_r(preg_split('/(?<!^)(?!$)/u', $test));
print_r(mb_str_split($test));
print_r(mb_split('/./',$test));
?>

outputs:
Array
(
    [0] => ә
    [1] => Ә
    [2] => 火
    [3] => 车
    [4] => 票
    [5] => a
    [6] => b
    [7] => c
)
Array
(
    [0] => ә
    [1] => Ә
    [2] => 火
    [3] => 车
    [4] => 票
    [5] => a
    [6] => b
    [7] => c
)
Array
(
    [0] => әӘ火车票abc
)