All C++ compilers come with classes for streaming input from the
console and output to the console. These classes are defined by
putting the directive #include <iostream> at the top of
the code. The istream class has methods for detecting
input errors and the end of input data. The ostream
class has methods for formatting output, i.e. specifying scientific
notation, fixed decimal notation, or a combination thereof, and for
specifying the number of decimal digits displayed. Using some of the
features of these classes, we add the capability of reading and
writing our own custom types. Finally, the ifstream and
ofstream classes let us read from and write to named
files.
Before we look at the features of the various streaming classes, let's look at how Unix deals with input and output.
cin, cout, and cerr