C++ Tutorial/File Stream/istreambuf iterator

/* 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 <iterator>
using namespace std;
int main()
{
    // input stream buffer iterator for cin
    istreambuf_iterator<char> inpos(cin);
    // end-of-stream iterator
    istreambuf_iterator<char> endpos;
    // output stream buffer iterator for cout
    ostreambuf_iterator<char> outpos(cout);
    // while input iterator is valid
    while (inpos != endpos) {
        *outpos = *inpos;    // assign its value to the output iterator
        ++inpos;
        ++outpos;
    }
}