STL迭代器

STL迭代器 STL迭代器： 顺序迭代器插入型迭代器iterator（正向迭代器）insert_iterator （随机插入型）reverse_iterator（反向迭代器）back_insert_iterator（后插型）const_iterator（常量正向迭代器）front_insert_iterator（前插型）reverse_const_iterator（常量反向迭代器） 流迭代器ostream_iterator（输出）ostream_iteratorito(cout, " ")istream_iterator（输入）istream_iteratoriti(cin) 1.顺序迭代器—遍历型迭代器 1.1:iterator 正向迭代器

//正向打印模板函数

//正向打印模板函数
template 
void show_it(T& con)
{
	typename T::iterator it = con.begin();
	for (; it != con.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

vector v1;
	vector v2;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	show_it(v1);
	

输出：0 1 2 3 4 5 6 7 8 9

1.2：reverse_iterator 反向迭代器

//vector::iterator it = v1.begin();end()//正向迭代器
//vector::reverse_iterator it = v1.rbegin();rend()//反向迭代器

//反向打印模板函数

template 
void show_cr(T& src)
{
	typename T::const_reverse_iterator it = src.crbegin();
	for (; it != src.crend(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

vector v1;
	vector v2;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	show_it(v1);
	show_n(v1);

1.3：const_iterator 常量正向迭代器

vector::const_iterator it2 = v2.cbegin();//常量迭代器vector::const_reverse_iterator it1 = v2.crbegin();//反向常量迭代器

正向打印常量模板函数

template
void show_const(const CON& src)
{
	typename CON::const_iterator it = src.cbegin();
	for (; it != src.cend(); it++)
	{
		cout << *it << "  ";
	}
	cout << endl;
}

1.4：reverse_const_iterator 常量反向迭代器

//函数模板，常量反向打印容器内元素

//函数模板，常量反向打印容器内元素
template
void show_reverse_const(CON& src)
{
	typename CON::const_reverse_iterator it = src.crbegin();
	for (; it != src.crend(); it++)
	{
		cout << *it << "  ";
	}
	cout << endl;
}

2.插入型迭代器

2.1：insert_iterator 随机插入型迭代器 ----- insert
随机插入即能在任意位置插入。

vector v1;
	vector v2;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	show_it(v1);
	//show_n(v1);
	insert_iterator < vector>it(v2, v2.begin());
	for (int i = 0; i < 10; i++)
	{
		*it = i + 100;
	}
	show_it(v2);
	insert_iterator>it1(v2, v2.begin()+1);
	Insert(v1.begin(), v1.end(), it1);//也可把it1直接定义为inserter(v2,v2.begin())

//函数模板封装类模板的产生

insert_iterator minserter(T& con, typename T::iterator it)//返回类型是insert_iterator，传参时（对象，迭代器）
{
	return insert_iterator(con, it);
}




Insert(v1.begin(),  v1.end(), inserter(v2,v2.begin() + 1));
Insert(v1.begin(), v1.end(), minserter(v2, v2.begin() + 1));

2.2：back_insert_iterator 后插型迭代器 ------ push_back();

back_insert_iteratormback_inserter(T& con)
{
	return back_insert_iterator(con);
}

vector v1;
	vector v2;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	show_it(v1);
	insert_iterator < vector>it(v2, v2.begin());
	for (int i = 0; i < 10; i++)
	{
		*it = i + 100;
	}
	show_it(v2);
	back_insert_iterator>it2(v2);
	*it2 = 999;
	show_it(v2);
	Insert(v1.begin(), v1.begin() + 4, back_inserter(v2));//和inserter相同
	show_it(v2);
	Insert(v1.begin(), v1.begin() + 4,mback_inserter(v2));
	show_it(v2);

2.3：front_insert_iterator 前插型迭代器 ----- push_front
前插存在于list.

list list1;
	for (int i = 0; i < 10; i++)
	{
		list1.push_back(i);
	}
	front_insert_iterator> it3(list1);

	auto it4 = front_inserter(list1);
	*it3 = 888;
	*it4 = 777;
	show(list1);

3.流迭代器：（输入和输出） 3.1：输出

ostream_iteratorito(cout, " ");
	for (int i = 0; i < 10; i++)
	{
		ito = i;
	}
	cout << endl;

3.2：输入

istream_iteratoriti(cin);
	int a;
	a = *iti;
	ostream_iteratorito(cout, " ");
	ito = a;