Remove non-utf8 characters from string

Question

Im having a problem with removing non-utf8 characters from string, which are not displaying properly. Characters are like this 0x97 0x61 0x6C 0x6F (hex representation)

Answer 1

I have made a function that deletes invalid UTF-8 characters from a string. I'm using it to clear description of 27000 products before it generates the XML export file.

public function stripInvalidXml($value) {
    $ret = "";
    $current;
    if (empty($value)) {
        return $ret;
    }
    $length = strlen($value);
    for ($i=0; $i < $length; $i++) {
        $current = ord($value{$i});
        if (($current == 0x9) || ($current == 0xA) || ($current == 0xD) || (($current >= 0x20) && ($current <= 0xD7FF)) || (($current >= 0xE000) && ($current <= 0xFFFD)) || (($current >= 0x10000) && ($current <= 0x10FFFF))) {
                $ret .= chr($current);
        }
        else {
            $ret .= "";
        }
    }
    return $ret;
}