$cen = iconv("gb2312","utf-8",$sp->SplitRMM($str));

改为：

$cen = iconv("gb2312","utf-8//TRANSLIT//IGNORE",$sp->SplitRMM($str));

The output charset.

If you append the string //TRANSLIT to out_charset transliteration is activated. This means that when a character can’t be represented in the target charset, it can be approximated through one or several similarly looking characters. If you append the string //IGNORE, characters that cannot be represented in the target charset are silently discarded. Otherwise, str is cut from the first illegal character and an E_NOTICE is generated.