Cpp中流继承关系

typedef basic_ios<char, char_traits<char> > ios;
typedef basic_streambuf<char, char_traits<char> > streambuf;
typedef basic_istream<char, char_traits<char> > istream;
typedef basic_ostream<char, char_traits<char> > ostream;
typedef basic_iostream<char, char_traits<char> > iostream;
typedef basic_stringbuf<char, char_traits<char>, allocator<char> > stringbuf;
typedef basic_istringstream<char, char_traits<char>, allocator<char> > istringstream;
typedef basic_ostringstream<char, char_traits<char>, allocator<char> > ostringstream;
typedef basic_stringstream<char, char_traits<char>, allocator<char> > stringstream;
typedef basic_filebuf<char, char_traits<char> > filebuf;
typedef basic_ifstream<char, char_traits<char> > ifstream;
typedef basic_ofstream<char, char_traits<char> > ofstream;
typedef basic_fstream<char, char_traits<char> > fstream;