The GetDirectoryName method returns the destination directory entered by the user in the File Save As dialog and contained in the DlgResults component.
_bstr_t bstrDirectoryName = spIDlgResults->GetDirectoryName();
...
// Retrieve the filename and destination directory entered by the user
IDlgResultsPtr spIDlgResults(spIFileSaveAsDlg);
std::cout << "FileName=" << (LPCSTR) spIDlgResults->GetFileName() << std::endl;
std::cout << "DirectoryName=" << (LPCSTR) spIDlgResults->GetDirectoryName() << std::endl;
std::cout << "FullPathName=" << (LPCSTR) spIDlgResults->GetFullPathName() << std::endl;
...