libio is distributed with a complete implementation of the ANSI C
stdio facility. It is implemented using streambuf
objects. See section Wrappers for C stdio.
The stdio package is intended as a replacement for the whatever
stdio is in your C library.
Since stdio works best when you build libc to contain it, and
that may be inconvenient, it is not installed by default.
Extensions beyond ANSI:
FILE is identical to a streambuf.
Hence there is no need to worry about synchronizing C and C++
input/output--they are by definition always synchronized.
FILE from C. Thus the system is extensible using the standard
streambuf protocol.
ungetc() buffer.