Assuming the target is also a wstring type, this should work. IE: std::wstring newstr = first + L" " + second;
Note that you left off the second colon in your variable definitions. This may be your problem. What error are you getting? The following is a test program that I just wrote to test this on Linux using GCC 4.4.7. It works fine and the output is "John Doe" as expected.
std::wstring first = L"John";
std::wstring second = L"Doe";
std::wstring full = first + L" " + second;
std::wcout << full << std::endl;
I would have been a bit more snarky if you said you lived on the Ile de la Cite. :-) I don't think Notre Dame has student housing on the island... I spent a month on the Rive Gauche when I was a teen - even climbed to the top of Notre Dame with my father - no hunchback there though! What a dissapointment!