ATL CComBSTR

CComBSTR is a convenience class for handling BSTRs. It’s convenient, but not full-featured. For advanced operations, sometimes ya gotta convert to a std::wstring and use the STL.

_bstr_t is a VC++ compiler COM support extension. It’s compiler native, so there’s no dependency on atl.dll.

References

CComBSTR Class | Microsoft Learn