C++ string与QString中文字符转换关系

std::string oldString = "你好，hello world";
QString newString = QString::fromLocal8Bit(oldString.c_str())

QString oldString = "你好，hello world";
std::string newString = std::string((const char *)oldString.toLocal8Bit().constData());

char *wchar2char(const wchar_t* source)
{
    char * data;
    int len= WideCharToMultiByte( CP_ACP ,0,source ,wcslen( source ), nullptr,0, nullptr ,nullptr);
    data= new char[len+1];
    WideCharToMultiByte( CP_ACP ,0,source ,wcslen( source ),data,len, nullptr ,nullptr);
    data[len]= '\0';
    return data;
}

const char *stringToChar(const std::string& str)
{
    std::wstring wstr = L"";
    int len = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), str.size(), nullptr, 0);
    wchar_t* wchar = new wchar_t[len + 1];
    MultiByteToWideChar(CP_UTF8, 0, str.c_str(), str.size(), wchar, len);
    wchar[len] = '\0';
    wstr.append(wchar);
    const char *data = wchar2char(wchar);
    delete[] wchar;
    return data;
}