cin                  Output Stream


        In C++, cerr corresponds to stderr. You can work with cerr like
    this: cerr<<x, where x is a data type or object, and << is the
    overloaded left shift operator, also called the insertion operator
    in C++. Note that cerr is also an alias for ostream_withassign, and
    that it is an unbuffered form of clog.

    Note:   You can also chain the use of << and >> like this:
            cout << "This is the value of x:" << x << "\n"; You do not
            need to worry about the type of the arguments you pass
            -- the << and >> operators are overloaded to handle all
            standard types, and you can even overload them for your own
            types.

            In addition, you can format error output with the
            cerr.setf() member function -- see Formatting for more
            details.