const char *p = "D:";
const WCHAR *pwcsName; //LPCWSTR
// required size
int size = MultiByteToWideChar(CP_ACP, 0, p, -1, NULL, 0);
// allocate it
pwcsName = new WCHAR[nChars];
MultiByteToWideChar(CP_ACP, 0, p, -1, (LPWSTR)pwcsName, size);
// use it....
// delete it
delete [] pwcsName;
}