stdio
A stdiobuf is a streambuf object that points to
a FILE object (as defined by stdio.h).
All streambuf operations on the stdiobuf are forwarded
to the FILE. Thus the stdiobuf object provides a
wrapper around a FILE, allowing use of streambuf
operations on a FILE. This can be useful when mixing
C code with C++ code.
The pre-defined streams cin, cout, and cerr are
normally implemented as stdiobuf objects that point to
respectively stdin, stdout, and stderr. This is
convenient, but it does cost some extra overhead.
If you set things up to use the implementation of stdio provided
with this library, then cin, cout, and cerr will be
set up to to use stdiobuf objects, since you get their benefits
for free. See section C Input and Output.