目录
1、list的介绍和使用:
1、结构:
2、接口函数:
迭代器遍历:
void listtest1()
{
list<int> lt;
lt.push_back(1);
lt.push_back(2);
lt.push_back(3);
lt.push_back(4);
//list<int>::iterator it = lt.begin();
auto it = lt.begin();
while (it != lt.end())
{
cout << *it << " ";
it++;
}
cout << endl;
for (auto e : lt)
{
cout << e << " ";
}
}
增删查改:
void listtest2()
{
//创建1234的链表
list<int> lt;
lt.push_back(1);
lt.push_back(2);
lt.push_back(3);
lt.push_back(4);
lt.push_front(10);
lt.push_front(20);
for (auto e : lt)
{
cout << e << " ";
}
cout << endl;
//定义迭代器
list<int>::iterator it = lt.begin();
//在3的前面增加一个30
it = find(lt.begin(), lt.end(), 3);
if (it != lt.end())
{
lt.insert(it, 30);
// insert以后,it不失效
}
for (auto e : lt)
{
cout << e << " ";
}
cout << endl;
//将迭代器找到3的位置
it = find(lt.begin(), lt.end(),3);
//删除3,先判断,在进行删除
if (it != lt.end())
{
lt.erase(it);
}
for (auto e : lt)
{
cout << e << " ";
}
}
翻转与排序:
void listtest3()
{
list<int> lt;
lt.push_back(1);
lt.push_back(3);
lt.push_back(2);
lt.push_back(4);
lt.push_front(20);
lt.push_front(10);
for (auto e : lt)
{
cout << e << " ";
}
cout << endl;
cout << "用算法里面的翻转后:" << endl;
reverse(lt.begin(), lt.end());
for (auto e : lt)
{
cout << e << " ";
}
cout << endl;
cout << "用自己容器里面的翻转后:" << endl;
lt.reverse();
for (auto e : lt)
{
cout << e << " ";
}
cout << endl;
cout << "排序后:" << endl;
lt.sort();
for (auto e : lt)
{
cout << e << " ";
}
cout << endl;
}
2、list的模拟实现:
1、节点的封装:
template<class T>
struct list_node
{
list_node<T>* _next;
list_node<T>* _prev;
T _val;
list_node(const T T())
:_next(nullptr)
,_prev(nullptr)
,_val(val)
{}
};
2、迭代器的封装:
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->_val;
}
Ptr operator->()
{
return &_node->_val;
}
self& operator++()
{
_node = _node->_next;
return *this;
}
self operator++(int)
{
self tmp(*this);
_node = _node->_next;
return tmp;
}
self& operator--()
{
_node = _node->_prev;
return *this;
}
self operator--(int)
{
self tmp(*this);
_node = _node->_prev;
return tmp;
}
bool operator!=(const self& it) const
{
return _node != it._node;
}
bool operator==(const self& it) const
{
return _node == it._node;
}
};
3、list的模拟实现:
1、typedef的几个类型:
typedef list_node<T> Node;
public:
typedef __list_iterator<T, T&, T*> iterator;
typedef __list_iterator<T, const T&, const T*> const_iterator;
2、迭代器的begin和end实现:
iterator begin()
{
return iterator(_head->_next);
}
iterator end()
{
return iterator(_head);
}
const_iterator begin() const
{
return const_iterator(_head->_next);
}
const_iterator end() const
{
return const_iterator(_head);
}
3、构造,拷贝构造与析构:
void empty_init()
{
_head = new Node;
_head->_next = _head;
_head->_prev = _head;
_size = 0;
}
list()
{
empty_init();
}
list(const list<T>& lt)
{
empty_init();
for (auto& e : lt)
{
push_back(e);
}
}
~list()
{
clear();
delete _head;
_head = nullptr;
}
void clear()
{
iterator it = begin();
while (it != end())
{
it = erase(it);
}
_size = 0;
}
4、插入和删除:
//在pos位置之前插入,最后返回新节点
iterator insert(iterator pos, const T& x)
{
Node* cur = pos._node;
Node* prev = cur->_prev;
Node* newnode = new Node(x);
prev->_next = newnode;
newnode->_next = cur;
cur->_prev = newnode;
newnode->_prev = prev;
++_size;
return newnode;
}
//删除pos位置的节点,最后返回的是pos位置的下一个节点,注意不能删除哨兵位
//erase存在迭代器失效问题,可以用返回值来解决这个问题
iterator erase(iterator pos)
{
assert(pos != end());
Node* cur = pos._node;
Node* next = cur->_next;
Node* prev = cur->_prev;
next->_prev = prev;
prev->_next = next;
delete cur;
--_size;
return next;
}
5、其他:
void swap(list<T>& it)
{
std::swap(_head, it._head);
std::swap(_size, it._size);
}
list<T>& operator=(list<T> lt)
{
swap(lt);
return *this;
}
size_t size()
{
return _size;
}
完整代码:
#pragma once
#include<assert.h>
namespace ppr
{
template<class T>
struct list_node
{
list_node<T>* _next;
list_node<T>* _prev;
T _val;
list_node(const T T())
:_next(nullptr)
,_prev(nullptr)
,_val(val)
{}
};
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->_val;
}
Ptr operator->()
{
return &_node->_val;
}
self& operator++()
{
_node = _node->_next;
return *this;
}
self operator++(int)
{
self tmp(*this);
_node = _node->_next;
return tmp;
}
self& operator--()
{
_node = _node->_prev;
return *this;
}
self operator--(int)
{
self tmp(*this);
_node = _node->_prev;
return tmp;
}
bool operator!=(const self& it) const
{
return _node != it._node;
}
bool operator==(const self& it) const
{
return _node == it._node;
}
};
template<class T>
class list
{
typedef list_node<T> Node;
public:
typedef __list_iterator<T, T&, T*> iterator;
typedef __list_iterator<T, const T&, const T*> const_iterator;
iterator begin()
{
return iterator(_head->_next);
}
iterator end()
{
return iterator(_head);
}
const_iterator begin() const
{
return const_iterator(_head->_next);
}
const_iterator end() const
{
return const_iterator(_head);
}
void empty_init()
{
_head = new Node;
_head->_next = _head;
_head->_prev = _head;
_size = 0;
}
list()
{
empty_init();
}
list(const list<T>& lt)
{
empty_init();
for (auto& e : lt)
{
push_back(e);
}
}
void swap(list<T>& it)
{
std::swap(_head, it._head);
std::swap(_size, it._size);
}
list<T>& operator=(list<T> lt)
{
swap(lt);
return *this;
}
~list()
{
clear();
delete _head;
_head = nullptr;
}
void clear()
{
iterator it = begin();
while (it != end())
{
it = erase(it);
}
_size = 0;
}
void push_back(const T& x)
{
/*Node* tail = _head->_prev;
Node* newnode = new Node(x);
tail->_next = newnode;
newnode->_prev = tail;
newnode->_next = _head;
_head->_prev = newnode;*/
insert(end(), x);
}
void push_front(const T& x)
{
insert(begin(), x);
}
void pop_back()
{
erase(--end());
}
void pop_front()
{
erase(begin());
}
//在pos位置之前插入,最后返回新节点
iterator insert(iterator pos, const T& x)
{
Node* cur = pos._node;
Node* prev = cur->_prev;
Node* newnode = new Node(x);
prev->_next = newnode;
newnode->_next = cur;
cur->_prev = newnode;
newnode->_prev = prev;
++_size;
return newnode;
}
//删除pos位置的节点,最后返回的是pos位置的下一个节点,注意不能删除哨兵位
//erase存在迭代器失效问题,可以用返回值来解决这个问题
iterator erase(iterator pos)
{
assert(pos != end());
Node* cur = pos._node;
Node* next = cur->_next;
Node* prev = cur->_prev;
next->_prev = prev;
prev->_next = next;
delete cur;
--_size;
return next;
}
size_t size()
{
return _size;
}
private:
Node* _head;
size_t _size;
};
}