The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
// stream for hexadecimal standard output
ostream hexout(cout.rdbuf());
hexout.setf (ios::hex, ios::basefield);
hexout.setf (ios::showbase);
// switch between decimal and hexadecimal output
hexout << "hexout: " << 177 << " ";
cout << "cout: " << 177 << " ";
hexout << "hexout: " << -49 << " ";
cout << "cout: " << -49 << " ";
hexout << endl;
}