stream for hexadecimal standard output : ostream « File Stream « C++ Tutorial

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/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#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;
}

hexout: 0xb1 cout: 177 hexout: 0xffffffcf cout: -49