Aspell does not use C++ I/O classes and functions in any way since they do not provide a way to get at the underlying file number and can often be slower than the highly tuned C I/O functions found in the standard C library. However, some lightweight wrapper classes are provided so that standard C I/O can be used in a more C++ like way.
These two base classes mimic some of the functionally of the C++ functionally of the corresponding classes. They are defined in istream.hpp and ostream.hpp respectively. They are however based on standard C I/O and are not proper C++ streams.
Defined in fstream.hpp.
CERR. Defined in iostream.hpp.