Attempting to stream an integer_t to/from a wide stream (e.g. std::wcout, std::wcin) fails to compile on MSVC2010 because wide streams don't have insertion/extraction operator overloads defined for std::string, only for std::wstring. To take this a bit further, as you probably know, Windows development is heavily biased towards usage of wchar_t over char, so it feels somewhat limited (or at least clumsy) that integer_t doesn't work directly with wchar_t strings/ streams/pointers. For example, integer_t has constructors that take char const*, but no constructors that take wchar_t const*; also, xint::to_string explicitly returns std::string, with no direct way to get a std::wstring instead. It would be nice if this was remedied so that working with wchar_t-based types was as painless as it currently is for char-based types.