注意：如果无法转换参数类型，则函数返回 NULL。
基于包“symfony/polyfill-mbstring”的 PHP < 7.4 的 Polyfill
<?php
function mb_str_split($string, $split_length = 1, $encoding = null)
{
if (null !== $string && !\is_scalar($string) && !(\is_object($string) && \method_exists($string, '__toString'))) {
trigger_error('mb_str_split(): expects parameter 1 to be string, '.\gettype($string).' given', E_USER_WARNING);
return null;
}
if (null !== $split_length && !\is_bool($split_length) && !\is_numeric($split_length)) {
trigger_error('mb_str_split(): expects parameter 2 to be int, '.\gettype($split_length).' given', E_USER_WARNING);
return null;
}
$split_length = (int) $split_length;
if (1 > $split_length) {
trigger_error('mb_str_split(): The length of each segment must be greater than zero', E_USER_WARNING);
return false;
}
if (null === $encoding) {
$encoding = mb_internal_encoding();
} else {
$encoding = (string) $encoding;
}
if (! in_array($encoding, mb_list_encodings(), true)) {
static $aliases;
if ($aliases === null) {
$aliases = [];
foreach (mb_list_encodings() as $encoding) {
$encoding_aliases = mb_encoding_aliases($encoding);
if ($encoding_aliases) {
foreach ($encoding_aliases as $alias) {
$aliases[] = $alias;
}
}
}
}
if (! in_array($encoding, $aliases, true)) {
trigger_error('mb_str_split(): Unknown encoding "'.$encoding.'"', E_USER_WARNING);
return null;
}
}
$result = [];
$length = mb_strlen($string, $encoding);
for ($i = 0; $i < $length; $i += $split_length) {
$result[] = mb_substr($string, $i, $split_length, $encoding);
}
return $result;
}
?>
