实现接口：
-
list的无参构造、n个val构造、拷贝构造
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operator=重载
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实现迭代器
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push_back()
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push_front()
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erase()
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insert()
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头尾删
#pragma once
#include<iostream>
#include<assert.h>
using namespace std;namespace liu
{
//定义list节点
template<class T>
struct list_node
{
T _data;
list_node<T>* _prev;
list_node<T>* _next;list_node(const T& x=T()) :_data(x) ,_prev(nullptr) ,_next(nullptr) {} }; template<class T,class Ref,class Ptr> struct list_iterator { typedef list_node<T>Node; typedef list_iterator<T, Ref, Ptr>Self; Node* _node; list_iterator(Node* node) :_node(node) {} Ref operator*() { return _node->_data; } Ptr operator->() { return &_node->_data; } Self& operator++() { _node = _node->_next; return *this; } Self& operator--() { _node = _node->_prev; return *this; } bool operator!=(const Self& s) { return _node != s._node; } bool operator==(const Self& s) { return _node == s._node; } }; template<class T> class list { //链表存储链表节点 typedef list_node<T> Node; public: //实现接口 typedef list_iterator<T, T&, T*>iterator; typedef list_iterator<T, const T&, const T*> const_iterator; void empty_init() { _head = new Node(); _head->_prev = _head; _head->_next = _head; } list()//无参构造 { empty_init(); } list(size_t n,const T& val=T())//n个val { empty_init(); for (int i=0;i<n;i++) { push_back(val); } } list(const list<T>& i1) { empty_init(); for(auto& x:i1) { push_back(x); } } ~list() { clear(); delete _head; _head = nullptr; } void clear() { auto it = begin(); while (it!=end()) { it=erase(it); } } iterator begin() { return iterator(_head->_next); } const_iterator begin()const { return const_iterator(_head->_next); } iterator end() { return iterator(_head); } const_iterator end()const { return const_iterator(_head); } iterator insert(iterator pos,const T&val) { Node* new_node = new Node(val); Node* cur = pos._node; Node* prev = cur->_prev; prev->_next = new_node; new_node->_prev = prev; cur->_prev = new_node; new_node->_next = cur; return iterator(new_node); } iterator erase(iterator pos) { assert(pos!=end()); Node* del = pos._node; Node* prev = del->_prev; Node* next = del->_next; prev->_next = next; next->_prev = prev; delete del; return iterator(next); } void pop_front() { erase(begin()); } void pop_back() { erase(--end()); } void swap(list<T>& i1) { std::swap(_head,i1._head); } list<T>& operator=(list<T> il) { swap(il); return *this; } void push_back(const T& x) { /*Node* new_node = new Node(x); Node* tail = _head->_prev; tail->_next = new_node; new_node->_prev = tail; new_node->_next = _head; _head->_prev = new_node;*/ insert(end(),x); } void push_front(const T& x) { /*Node* new_node = new Node(x); Node* prev = _head->_next; _head->_next = new_node; new_node->_prev = _head; prev->_prev = new_node; new_node->_next = prev;*/ insert(begin(), x); } private: Node* _head;//双端链表，哨兵位 }; template<class T> void swap(T&a,T& b) { T c(a); a = b; b = c; } template<class T> void swap(list<T>& a, list<T>& b) { a.swap(b); } void test1() { /*liu::list<int>i1; i1.push_back(1); i1.push_back(2); i1.push_back(3); i1.push_back(4); i1.push_front(5); i1.push_front(6); i1.push_front(7); liu::list<int>::iterator it1 = i1.begin(); while (it1!=i1.end()) { cout << *it1 << " "; ++it1; } cout << endl; liu::list<int>::iterator it2 = i1.begin(); it2=i1.erase(it2); while (it2 != i1.end()) { cout << *it2 << " "; ++it2; }*/ liu::list<int>i1(10,1); liu::list<int>i2(10,2); liu::swap(i1, i2); for (auto x : i2) { cout << x << " "; } cout << endl; for (auto x : i1) { cout << x << " "; } cout << endl; }}