Overloading OSTREAM

example.cpp

#include <cassert>
#include <functional>
#include <iostream>
#include <vector>

std::vector<int> V;

template <typename Container1, typename Container2>
std::ostream&
operator<<(std::ostream& ostr, const std::pair<Container1&, Container2&> data)
{
	auto head1 = data.first.begin();
	auto tail1 = data.first.end();
	auto head2 = data.second.begin();
	auto tail2 = data.second.end();

	assert(std::distance(head1, tail1) ==
	       std::distance(head2, tail2));

	size_t distance = std::distance(head1, tail1);
	while (head1 != tail1
	    && head2 != tail2) {
		ostr << *head1 << ", " << *head2 << "\n";
		++head1;
		++head2;
	}

	return ostr;
}

template <typename Container1, typename Container2>
std::ostream&
operator<<(std::ostream& ostr, const std::pair<Container1, Container2> data)
{
	auto head1 = data.first.begin();
	auto tail1 = data.first.end();
	auto head2 = data.second.begin();
	auto tail2 = data.second.end();

	assert(std::distance(head1, tail1) ==
	       std::distance(head2, tail2));

	size_t distance = std::distance(head1, tail1);
	while (head1 != tail1
	    && head2 != tail2) {
		ostr << *head1 << ", " << *head2 << "\n";
		++head1;
		++head2;
	}

	return ostr;
}

int
main()
{
	V.push_back(0);
	V.push_back(2);
	V.push_back(1);
	std::cout << std::make_pair(std::ref(V), std::ref(V));
	std::cout << std::make_pair(V, V);
}