private:     static std::vector<std::string> parseUTF8(const std::string &str);public:    static std::string subUTF8(const std::string &str, int from, int to);

std::vector<std::string> A::parseUTF8(const std::string &str){    int l = str.length();    std::vector<std::string> ret;    ret.clear();    for(int p = 0; p < l; )     {        int size=0;        unsigned char c = str[p];        if(c < 0x80) {            size = 1;        }        else if(c < 0xc2)         {            size = 2;        }         else if(c < 0xe0)        {            size = 2;        }         else if(c < 0xf0)        {            size = 3;        }         else if(c < 0xf8)         {            size = 4;        }         else if (c < 0xfc)         {            size = 5;        }         else if (c < 0xfe)        {            size = 6;        }        else            size = 7;        std::string temp = "";        temp = str.substr(p, size);        ret.push_back(temp);        p += size;    }    return ret;}std::string A::subUTF8(const std::string &str,int from, int to){    if(from > to) return "";     if (str.length() < to) return "";    std::vector<std::string> vstr = parseUTF8(str);     std::vector<std::string>::iterator iter=vstr.begin();    std::string res;    std::string result;    for(iter=(vstr.begin() + from); iter != (vstr.begin() + to); iter++)    {        res += *iter;    }    return res;}