Remember that the input operator >>
stops reading at whitespace.
Use e.g. std::getline
to get the remainder of the string:
std::stringstream ss("123ABCDEF1And then the rest of the string");
ss >> std::setw(3) >> nId
>> std::setw(6) >> sLabel
>> std::setw(1) >> bFlag;
std::getline(ss, sLeftovers);