According to the document of PHP official website, http://php.net/manual/en/function.str-split.php
str_split
(PHP 5) str_split — Convert a string to an array
So, it’s only for PHP5+. In PHP4, we use this function below:
<? if (!function_exists('str_split')) { function str_split($text, $split = 1) { if (!is_string($text)) return false; if (!is_numeric($split) && $split < 1) return false; $len = strlen($text); $array = array(); $i = 0; while ($i < $len) { $key = null; for ($j = 0; $j < $split; $j += 1) { $key .= $text{$i}; $i += 1; } $array[] = $key; } return $array; } } ?>
or these functions below:
<? if (!function_exists('str_split')) { function str_split($string, $chunksize = 1) { preg_match_all('/(' . str_repeat('.', $chunksize) . ')/Us', $string, $matches); return $matches[1]; } } ?>
<?php if (!function_exists('str_split')) { function str_split($string, $length = 1) { if (strlen($string) > $length || !$length) { do { $c = strlen($string); $parts[] = substr($string, 0, $length); $string = substr($string, $length); } while ($string !== false); } else { $parts = array($string); } return $parts; } } ?>