Plain C I/O
C++ has two standard I/O systems. The iostreams library was created for
C++, and uses features essential to that language. The stdio library
was created for plain C, and, like the rest of C remains.
So far, we have limited ourselves to iostreams, which is much
superior in most respects. However, if you ever have a need to
write programs in pure plain C, you'll have know something about
The standard streams are stdin, stdout and stderr,
which are defined as FILE *.
The primary calls are printf for output and scanf for
reading, but there are many others.