utility/transform_iterator_example.cpp

// (C) Copyright Jeremy Siek 2000. 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 <functional>
#include <algorithm>
#include <iostream>
#include <boost/iterator_adaptors.hpp>

int
main(int, char*[])
{
  // This is a simple example of using the transform_iterators class to
  // generate iterators that multiply the value returned by dereferencing
  // the iterator. In this case we are multiplying by 2.
  // Would be cooler to use lambda library in this example.

  int x[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
  const int N = sizeof(x)/sizeof(int);

  typedef std::binder1st< std::multiplies<int> > Function;
  typedef boost::transform_iterator_generator<Function, int*>::type doubling_iterator;

  doubling_iterator i(x, std::bind1st(std::multiplies<int>(), 2)),
    i_end(x + N, std::bind1st(std::multiplies<int>(), 2));

  std::cout << "multiplying the array by 2:" << std::endl;
  while (i != i_end)
    std::cout << *i++ << " ";
  std::cout << std::endl;

  std::cout << "adding 4 to each element in the array:" << std::endl;

  std::copy(boost::make_transform_iterator(x, std::bind1st(std::plus<int>(), 4)),
	    boost::make_transform_iterator(x + N, std::bind1st(std::plus<int>(), 4)),
	    std::ostream_iterator<int>(std::cout, " "));
  std::cout << std::endl;
  
  return 0;
}