utf8 和 gb2312 的转换

int chr2wch(const char* buffer, wchar_t* &wBuf)
{
      size_t len = strlen(buffer);

      size_t wlen = MultiByteToWideChar(CP_ACP, 0, (const char*)buffer, int(len), NULL, 0);

      wBuf = new wchar_t[wlen + 1];

      MultiByteToWideChar(CP_ACP, 0, (const char*)buffer, int(len), wBuf, int(wlen));
     wBuf[wlen] = 0;

     return (int)wlen;
}

int chr2utf(const char* buf, char* &mb_buf)
{
    WCHAR* wbuf;
    int wlen = chr2wch(buf, wbuf);
    int mb_buf_size = ::WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, NULL, 0, NULL, NULL);
    mb_buf = new char[mb_buf_size + 1];
    int mb_len = ::WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, mb_buf, mb_buf_size, NULL, NULL);
    mb_buf[mb_len] = 0;
    delete[] wbuf;
    return mb_len;
}


int utf2wch(const char* buffer, wchar_t* &wBuf)
{
    size_t len = strlen(buffer);

    size_t wlen = MultiByteToWideChar(CP_UTF8, 0, (const char*)buffer, int(len), NULL, 0);

    wBuf = new wchar_t[wlen + 1];

    MultiByteToWideChar(CP_UTF8, 0, (const char*)buffer, int(len), wBuf, int(wlen));
    wBuf[wlen] = 0;

    return (int)wlen;
}

int utf2chr(const char* buf, char* &mb_buf)
{
    WCHAR* wbuf;
    int wlen = utf2wch(buf, wbuf);
    int mb_buf_size = ::WideCharToMultiByte(CP_ACP, 0, wbuf, wlen, NULL, 0, NULL, NULL);
    mb_buf = new char[mb_buf_size + 1];
    int mb_len = ::WideCharToMultiByte(CP_ACP, 0, wbuf, wlen, mb_buf, mb_buf_size, NULL, NULL);
    mb_buf[mb_len] = 0;
    delete[] wbuf;
    return mb_len;
}

由于保存新的字符串的内存是堆上创建的，所以用完之后要 delete []out_msg;