istream_itreator

#include <iostream>
#include <list>
#include <fstream>
#include <algorithm>
#include <iterator>
#include "merge_sort.h"
using namespace std;
void incr(istream_iterator<int> file_iter)
{
    cout << *++(++file_iter) << endl;
}
void merge_sort(istream_iterator<int>& file_iter, istream_iterator<int>& end_of_stream)
{
    size_t size = distance(file_iter, end_of_stream);
    if (size > 1)
    {
        istream_iterator<int> it(file_iter);
        advance(it, size / 2);
        size_t const left_size = size / 2;
        size_t const right_size = size - left_size;

        merge_sort(file_iter, it);
        merge_sort(++it, end_of_stream);

        size_t lidx = 0, ridx = left_size, idx = 0;
        istream_iterator<int> itl(file_iter); // pointer to left element
        advance(itl, lidx);
        istream_iterator<int> itr(file_iter); // pointer to right element
        advance(itr, ridx);
        istream_iterator<int> itls(file_iter); // pointer to border element
        advance(itls, left_size);
        int* tmp_array = new int[size];

        while (lidx < left_size || ridx < size)
        {
            if (*itl < *itr)
            {
                tmp_array[idx++] = move(*itl);
                lidx++;
            }
            else
            {
                tmp_array[idx++] = move(*itr);
                ridx++;
            }

            if (lidx == left_size)
            {
                copy(itr,
                    end_of_stream,
                    &tmp_array[idx]);
                break;
            }
            if (ridx == size)
            {
                copy(itl,
                    itls,
                    &tmp_array[idx]);
                break;
            }
        }
        ofstream fo("forsort.dat");
        ostream_iterator<int> ositer(fo, "\n");
        copy(make_move_iterator(tmp_array), make_move_iterator(&tmp_array[size]), ositer);
    }
}

int main()
{
    ifstream fi("forsort.dat");

    // read data from file
    istream_iterator<int> file_iter(fi);
    istream_iterator<int> end_of_stream;

    //fstream out("forsort.dat", fstream::out);

    /*
    auto it = file_iter;
    for (int k = 0; k < 8; it++, k++)
        cout << *(it) << "\n";
    */
    //cout << *file_iter << endl << *(++file_iter) << endl << *file_iter << endl;
    size_t size = distance(file_iter, end_of_stream);
    cout << size << endl;
    incr(file_iter);
    //merge_sort(file_iter, end_of_stream);

    /*
    list<int> l;
    l.push_back(5);
    l.push_back(5);
    l.push_back(5);
    copy(l.begin(), l.end(), ositer);

    cout << *file_iter << " dist = " << distance(file_iter, end_of_stream) << endl;
    copy(file_iter, end_of_stream, back_inserter(i));

    cout << endl;

    ostream_iterator<int> ositer(cout, " - ");
    copy(i.begin(), i.end(), ositer);
    cout << endl;
    */
    system("PAUSE");
    return 0;
}