【C++】——list

文章目录

• list介绍和使用
• • list注意事项
• list模拟实现
• list和vector的不同

list介绍和使用

list注意事项

list模拟实现

#pragma once
#include <assert.h>
namespace rq
{
	template<class T>
	struct list_node
	{
		T _data;
		list_node<T>* _next;
		list_node<T>* _prev;

		list_node(const T& x = T())
			:_data(x)
			, _next(nullptr)
			, _prev(nullptr)
		{}
	};
	template<class T>
	struct list_iterator
	{
		typedef list_node<T> Node;
		typedef list_iterator<T> Self;
		Node* _node;

		list_iterator(Node* node)
			:_node(node)
		{}
		T& operator*()
		{
			return _node->_data;
		}
		T* operator&()
		{
			return _node->_data;
		}
		Self& operator++()
		{
			_node = _node->_next;
			return *this;
		}
		Self& operator--()
		{
			_node = _node->_prev;
			return *this;
		}
		bool operator!=(const Self& x)
		{
			return _node != x._node;
		}
		bool operator==(const Self& x)
		{
			return _node == x._node;
		}
	};
		
	template<class T>
	struct list_const_iterator
	{
		typedef list_node<T> Node;
		typedef list_const_iterator<T> Self;
		Node* _node;

		list_const_iterator(Node* node)
			:_node(node)
		{}
		
		const T& operator*()
		{
			return _node->_data;
		}
		const T* operator&()
		{
			return _node->_data;
		}
		Self& operator++()
		{
			_node = _node->_next;
			return *this;
		}
		Self& operator--()
		{
			_node = _node->_prev;
			return *this;
		}
		bool operator!=(const Self& x)
		{
			return _node != x._node;
		}
		bool operator==(const Self& x)
		{
			return _node == x._node;
		}
	};

	template<class T>
	class list
	{
		typedef list_node<T> Node;

	public:
		typedef list_iterator<T> iterator;
		typedef list_const_iterator<T> const_iterator;


		void clear()
		{
			auto it = begin();
			while (it != end())
			{
				it = erase(it);//erase以后会返回下一个位置
			}
		}
		void emtpy_init()
		{
			_head = new Node;
			_head->_next = _head;
			_head->_prev = _head;
			_size = 0;
		}
		list()
		{
			emtpy_init();
		}
		//拷贝构造
		list(const list<T>& lt)
		{
			emtpy_init();
			for (auto& e : lt)
			{
				push_back(e);
			}
		}
		list<T>& operator=(list<T> lt)
		{
			swap(lt);
			return *this;
		}

		~list()
		{
			clear();
			delete _head;
			_head = nullptr;
		}
		

		iterator begin()
		{
			/*iterator it(_head->_next);
			return it;*/

		/*	return iterator(_head->_next); 匿名对象*/
			return _head->_next;//接收指针，但是返回会隐式转换成iterator类型
		}
		iterator end()
		{
			return _head;
		}
		const_iterator begin() const 
		{
			/*iterator it(_head->_next);
			return it;*/

			/*	return iterator(_head->_next); 匿名对象*/
			return _head->_next;//接收指针，但是返回会隐式转换成iterator类型
		}
		const_iterator end() const 
		{
			return _head;
		}
		
		size_t size() const
		{
			return _size;
		}
		void swap(list<int>& it)
		{
			std::swap(_head, it._head); 
			std::swap(_size, it._size);
		}
		bool empty() const
		{
			return _size == 0;
		}
		void push_back(const T& x)
		{
			/*Node* newnode = new Node(x);
			Node* tail = _head->_prev;

			tail->_next = newnode;
			newnode->_prev = tail;
			newnode->_next = _head;
			_head->_prev = newnode;
			++_size;*/
			insert(end(), x);
		}
		void push_front(const T& x)
		{
			insert(begin(), x);
		}
		void pop_front()
		{
			erase(begin());
		}
		void pop_back()
		{
			erase(--end());
		}
		iterator erase(iterator pos)
		{
			assert(pos != end());//不能把头节点删了
			Node* prev = pos._node->_prev;
			Node* next = pos._node->_next;

			prev->_next = next;
			next->_prev = prev;
			--_size;

			return next;
		}
		iterator insert(iterator pos, const T& x)
		{
			//prev newnode cur
			Node* newnode = new Node(x);
			Node* prev = pos._node->_prev;
			Node* cur = pos._node;

			prev->_next = newnode;
			newnode->_prev = prev;
			newnode->_next = cur;
			cur->_prev = newnode;
			++_size;

			return newnode;
		}
	private:
		Node* _head;
		size_t _size;
	};
	template<class Container>
	void print_container(const Container& v)
	{
		list<int>::const_iterator it = v.begin();
		while (it != v.end())
		{
			//*it += 10;
			cout << *it << " ";
			++it;
		}
		cout << endl;
		for (auto e : v)
		{
			cout << e << " ";
		}
		cout << endl;
	}
	void test_list01()
	{
		list<int> lt;
		lt.push_back(1);
		lt.push_back(2);
		lt.push_back(3);
		lt.push_back(4);
		lt.push_back(5);
		
		print_container(lt);
		list<int>::iterator it = lt.begin();
		while (it != lt.end())
		{
			cout << *it << " ";
			++it;
		}
		cout << endl;
	}
}

test.cpp

#define   _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
#include<string>
#include <algorithm>
#include <list>
using namespace std;
void test_list1()
{
	string s("sgfaiug");
	cout << s << endl;
	sort(s.begin(), s.end());
	cout << s << endl;
}
void test_list2()
{
	list<int> lt;
	lt.push_back(1);
	lt.push_back(2);
	lt.push_back(3);
	lt.push_back(4);
	lt.push_back(5);
	for (auto e : lt)
	{
		cout << e << " ";
	}
	cout << endl;
	auto it = lt.begin();
	int k = 3;
	while (k--)
	{
		++it;
	}
	lt.insert(it, 30);
	for (auto e : lt)
	{
		cout << e << " ";
	}
	cout << endl;

	int x = 0;
	cin >> x;
	it = find(lt.begin(), lt.end(), x);
	if (it != lt.end())//迭代器从前往后找，左闭右开，等于end就是没找到
	{
		lt.erase(it);
	}
	for (auto e : lt)
	{
		cout << e << " ";
	}
	cout << endl;
}
#include "list.h"
int main()
{
	//test_list2();
	rq::test_list01();
	return 0;
}

list和vector的不同