Windows API: UTF8和UNICODE轉換

UTF-8與UNICODE編碼格式字符串的相互轉換：

//UTF-8轉Unicode 
std::wstring Utf82Unicode(const std::string& utf8string) 
{
    int widesize = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, NULL, 0);
    if (widesize == ERROR_NO_UNICODE_TRANSLATION)
    {
        throw std::exception("Invalid UTF-8 sequence.");
    }
    if (widesize == 0)
    {
        throw std::exception("Error in conversion.");
    }
    std::vector<wchar_t> resultstring(widesize);
    int convresult = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, &resultstring[0], widesize);
    if (convresult != widesize)
    {
        throw std::exception("La falla!");
    }
    return std::wstring(&resultstring[0]);
}

//unicode 轉為 ascii 
std::string WideByte2Acsi(std::wstring& wstrcode){
    int asciisize = ::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, NULL, 0, NULL, NULL);
    if (asciisize == ERROR_NO_UNICODE_TRANSLATION)
    {
        throw std::exception("Invalid UTF-8 sequence.");
    }
    if (asciisize == 0)
    {
        throw std::exception("Error in conversion.");
    }
    std::vector<char> resultstring(asciisize);
    int convresult = ::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, &resultstring[0], asciisize, NULL, NULL);
    if (convresult != asciisize)
    {
        throw std::exception("La falla!");
    }
    return std::string(&resultstring[0]);
}

 

//utf-8 轉 ascii 
std::string UTF_82ASCII(std::string& strUtf8Code)
{
    using namespace std;
    string strRet = "";
    //先把 utf8 轉為 unicode 
    wstring wstr = Utf82Unicode(strUtf8Code);
    //最后把 unicode 轉為 ascii 
    strRet = WideByte2Acsi(wstr);
    return strRet;
}