C++ STL（23）：Insert Iterator（插值迭代器）

#include <iostream>
#include <iterator>
#include <list>
#include <vector>
#include <set>
#include <algorithm>

//Iterator Classes迭代器类：Insert Iterator
int main()
{
	/************************************************************************/
	//template <class Container> class front_insert_iterator
	/************************************************************************/
	//class front_insert_iterator:插入顺序与新增元素的顺序刚好相反，将元素新增于开头处

	std::list<int> L;
	L.push_front(3);

	std::front_insert_iterator<std::list<int>> fL(L);
	*fL++ = 0;
	*fL++ = 1;
	*fL++ = 2;
	//2 1 0 3
	std::copy(L.begin(), L.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;

	//front_insert_iterator辅助函数front_inserter
	std::front_inserter(L) = 4;
	std::front_inserter(L) = 8;
	std::front_inserter(L) = 9;
	//9 8 4 2 1 0 3
	std::copy(L.begin(), L.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;


	std::vector<int> V;
	L.clear();
	std::generate_n(std::back_inserter(V), 10, []{return rand() % 50; });
	//41 17 34 0 19 24 28 8 12 14
	std::copy(V.begin(), V.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;

	std::copy(V.begin(), V.end(), std::front_inserter(L));
	//14 12 8 28 24 19 0 34 17 41
	std::copy(L.begin(), L.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;

	/************************************************************************/
	//template <class Container> class back_insert_iterator
	/************************************************************************/
	//class back_insert_iterator：把新增的元素置于尾端，顺序一致
	L.clear();
	L.push_front(2);
	std::back_insert_iterator<std::list<int>> bL(L);
	*bL++ = 1;
	*bL++ = 0;
	*bL++ = 3;
	using listIterator =  std::list<int>::iterator;
	//2 1 0 3
	for (listIterator it = L.begin(); it != L.end(); ++it)
	{
		std::cout << *it << " ";
	}
	std::cout << std::endl;

	//back_insert_iterator辅助函数back_inserter
	std::back_inserter(L) = 7;
	std::back_inserter(L) = 5;
	std::back_inserter(L) = 4;
	//2 1 0 3 7 5 4
	for (listIterator it = L.begin(); it != L.end(); ++it)
	{
		std::cout << *it << " ";
	}
	std::cout << std::endl;

	V.clear();
	std::copy(L.begin(), L.end(), std::back_inserter(V));
	//2 1 0 3 7 5 4
	std::copy(V.begin(), V.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;


	/************************************************************************/
	//template <class Container> class insert_iterator
	/************************************************************************/
	//class insert_iterator:在Container对象的指定位置插入数据
	listIterator it = L.begin();
	std::advance(it, 3);
	std::insert_iterator<std::list<int>> iL(L, it);
	*iL++ = 9;
	*iL++ = 8;
	*iL++ = 10;
	//2 1 0 9 8 10 3 7 5 4
	for (listIterator it = L.begin(); it != L.end(); ++it)
		std::cout << *it << " ";
	std::cout << std::endl;

	//insert_iterator辅助函数inserter
	std::advance(it, -2);
	std::inserter(L, it) = 4;
	std::inserter(L, it) = 7;
	std::inserter(L, it) = 0;
	//2 1 0 9 4 7 0 8 10 3 7 5 4
	std::copy(L.begin(), L.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;

	V.clear();
	L.clear();
	std::generate_n(std::back_inserter(V), 10, []{return rand() % 8; });
	std::generate_n(std::front_inserter(L), 10, []{return rand() % 10; });
	//vector V elements: 1 1 1 3 1 3 3 6 3 4
	std::cout << "vector V elements: ";
	std::copy(V.begin(), V.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;

	//list L elements: 5 8 6 1 2 2 3 2 4 1
	std::cout << "list L elements: ";
	std::copy(L.begin(), L.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;

	std::sort(V.begin(), V.end());
	L.sort();    //此处不能使用std::sort(L.begin(), L.end());
	std::set<int> s;
	std::merge(V.begin(), V.end(), L.begin(), L.end(), std::inserter(s, s.begin()));
	//set s elements: 1 2 3 4 5 6 8
	std::cout << "set s elements: ";
	std::copy(s.begin(), s.end(), std::ostream_iterator<int>(std::cout, " "));
	std::cout << std::endl;
	return 0;
}

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