ATL / WTL / STL

typedef struct {
    void *data;
    void *next_block;
}block;

std::string dwl::convertWstrToStdString(const std::wstring & wStr) {
   //The following code is modified from the examples at http://msmvps.com/blogs/gdicanio/
   //archive/2010/01/04/conversion-between-unicode-utf-16-and-utf-8-in-c-win32.aspx

   if (wStr == L"" || wStr.size()==0) return "";
   //Now, get the size of the required string:
   int origSize = wStr.size();
   origSize++; //For a NULL terminator
   DWORD conversionFlags = 0;
   //First, get the required size:
   int requiredSize = WideCharToMultiByte(CP_ACP, conversionFlags, wStr.c_str(),
               origSize, NULL, 0, NULL, NULL);
   if (requiredSize == 0)
               throw DwlException(_T("Bad Wide String to String conversion"));
   CStrWrap cStr(requiredSize+1);
   int result = WideCharToMultiByte(CP_ACP, conversionFlags, wStr.c_str(),
               origSize, cStr[0], requiredSize, NULL, NULL);
   if (result==0) throw DwlException(_T("Error converting string"));
   *cStr[result] = '\0';
   return std::string(cStr[0]);
   }

std::wstring dwl::convertStdStringToWString(const std::string & str) {
   //This converts a string to a UNICODE string by the method taken on
   //http://www.codeguru.com/forum/archive/index.php/t-231165.html.
   if (str.length() == 0) return L"";
   //Get the required length:
   int unicodeLength = MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.length(), 0, 0);
   ++unicodeLength;  //Add space for a NULL terminator.
   if (unicodeLength == 0) throw DwlException(_T("Empty conversion"));
   MbStrWrap wStr(unicodeLength);
   int result = MultiByteToWideChar(CP_ACP, 0, str.c_str(), str.length(), wStr[0],
               unicodeLength);
   if (result==0) throw DwlException(_T("Error converting string"));
   *wStr[result] = L'\0';
   return std::wstring(wStr[0]);
   }

wstring wstr(L"Wide String");
CStringA cstr(wstr.c_str());
string str(cstr);

str = "String";
CStringW wcstr(str.c_str());
wstr = wcstr;

_bstr_t bstr1(wstr.c_str());
str = (char*)bstr1;

_bstr_t bstr2(str.c_str());
wstr = (wchar_t*)bstr2;