iconv用法解读

来源：互联网发布：au软件录音保存编辑：程序博客网时间：2024/05/16 04:18
iconv是一个字符集转换函数，原型为：
size_t iconv(iconv_t cd,
char **inbuf, size_t *inbytesleft,
char **outbuf, size_t *outbytesleft);
// 传递给do_convert的in_buf，所有字节数（in_buf_size指定）都是可以转换成功的static int do_convert(iconv_t cd, const char* from, size_t from_size, std::string* to){    char* in_buf_ptr = const_cast<char*>(from);    size_t in_bytes_left = from_size;    size_t out_bytes = in_bytes_left*3 + 1;    size_t out_bytes_left = out_bytes;    std::string out(out_bytes_left, '\0');    char* out_buf_start = const_cast<char*>(out.c_str());    char* out_buf_ptr = out_buf_start;    int bytes = iconv(cd, &in_buf_ptr, &in_bytes_left, &out_buf_ptr, &out_bytes_left);    if (-1 == bytes)        return errno;    to->assign(out_buf_start, out_bytes-out_bytes_left);    return 0;}// 可忽略不能转换的部分，// 也可以在结果中保留不能被转换的部分// 详细实现可以浏览：// https://github.com/eyjian/mooon/blob/master/common_library/src/utils/charset_utils.cppvoid CCharsetUtils::convert(const std::string& from_charset, const std::string& to_charset,                            const std::string& from, std::string* to,                            bool ignore_error, bool skip_error) throw (CException){    std::string result; // 用来保存处理后的内容    char* in_buf = const_cast<char*>(from.c_str());    size_t in_bytes = from.size();   // 需要处理的总字节数    size_t in_bytes_left = in_bytes; // 剩余的未被处理的字节数    iconv_t cd = iconv_open(to_charset.c_str(), from_charset.c_str());    if ((iconv_t)(-1) == cd)    {        THROW_EXCEPTION(strerror(errno), errno);    }    while (in_bytes_left > 0)    {        int errcode;        size_t out_bytes = in_bytes_left * 3 + 1; // 保证足够大        size_t out_bytes_left = out_bytes;        std::string out(out_bytes_left, '\0');        char* out_buf = const_cast<char*>(out.c_str());        char* out_buf_start = out_buf;        char* in_buf_start = in_buf;        // 如果成功，返回值bytes为0        // 如果成功，in_buf指向in的结尾符，即'\0'，同时in_bytes_left值为0        // 如果失败，in_buf指向未能转换的起始地址，而in_bytes_left值为剩余的未被转换的（可能含有可转换的）字节数        // 如果成功，则out_bytes-out_bytes_left值为转换后的字节数        // 如果成功，则out_buf_start存储了被转换后的结果，有效长度为out_bytes-out_bytes_left        int bytes = iconv(cd, &in_buf, &in_bytes_left, &out_buf, &out_bytes_left);        if (bytes != -1)        {            result.append(out_buf_start, out_bytes-out_bytes_left);            break;        }        else if (!ignore_error)        {            errcode = errno;            iconv_close(cd);            THROW_EXCEPTION(strerror(errcode), errcode);        }        else        {            // EILSEQ An invalid multibyte sequence has been encountered in the input.            // EINVAL An incomplete multibyte sequence has been encountered in the input.            if ((errno != EINVAL) &&                (errno != EILSEQ))            {                // E2BIG  There is not sufficient room at *outbuf.                errcode = errno;                iconv_close(cd);                THROW_EXCEPTION(strerror(errcode), errcode);            }            else            {                // in_buf之前部分是可以转换的                if (in_buf != in_buf_start)                {                    std::string str;                    errcode = do_convert(cd, in_buf_start, in_buf-in_buf_start, &str);                    if (errcode != 0)                    {                        iconv_close(cd);                        THROW_EXCEPTION(strerror(errcode), errcode);                    }                    result.append(str);                }                // skip_error决定未能被转换的是否出现在结果当中                if (!skip_error)                {                    result.append(in_buf, 1);                }                // 往前推进                --in_bytes_left; // 将导致while语句结束                ++in_buf;            }        }    }    if (-1 == iconv_close(cd))    {        THROW_EXCEPTION(strerror(errno), errno);    }    // 不能直接使用to，因为to可能就是from    *to = result;}void CCharsetUtils::gbk_to_utf8(const std::string& from, std::string* to, bool ignore_error, bool skip_error) throw (CException){    convert("gbk", "utf-8", from, to, ignore_error, skip_error);}void CCharsetUtils::utf8_to_gbk(const std::string& from, std::string* to, bool ignore_error, bool skip_error) throw (CException){    convert("utf-8", "gbk", from, to, ignore_error, skip_error);}void CCharsetUtils::gb2312_to_utf8(const std::string& from, std::string* to, bool ignore_error, bool skip_error) throw (CException){    convert("gb2312", "utf-8", from, to, ignore_error, skip_error);}void CCharsetUtils::utf8_to_gb2312(const std::string& from, std::string* to, bool ignore_error, bool skip_error) throw (CException){    convert("utf-8", "gb2312", from, to, ignore_error, skip_error);}
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