STL-list类

 list的介绍和使用

         list的介绍

list的介绍list的介绍

        list是双向循环链表

          list的使用 

        构造

list(size_t n,const value_type& val = value_type())	构造的list中包含n个值为val的元素
list()	构造空list
lis(const list& x)	拷贝构造函数
list(inputlerator first,inputlterator last)	用[first,list)的区间中元素构造list

int main()
{list<int> A;list<int> B(5,1);list<int> C(B);list<int> D(C.begin(),C.end());return 0;
}

        迭代器

begin	返回第一个元素的迭代器
end	返回最后一个元素的下一个位置的迭代器
rbegin	返回最后一个元素的迭代器
rend	返回第一个元素的上一个位置的迭代器

 

 

 

 

begin与end是一组的正向地迭代器 ++向后移动

rbegin与rend是反向迭代器 ++向前移动

int main()
{int num[10] = { 1,2,3,4,5,6,7,8,9,10 };list<int> a(num,num+10);for (auto it = a.begin(); it != a.end(); it++){cout << *it << ' ';}cout << endl;for (auto rit = a.rbegin(); rit != a.rend(); rit++){cout << *rit << ' ';}cout << endl;for (auto ait : a){cout << ait;}return 0;
}

empty	检测list是否为空
size	返回list中有效节点数

front	返回list地第一个节点中值的引用
back	返回list最后一个节点中值的引用

 

 

 

 

 

 

push_front	头插
pop_front	头删
push_back	尾插
pop_back	尾删
insert	在pos位置插入
erase	删除pos位置元素
swap	交换元素
clear	清空有效元素

 

 

 

 

 

 

 

 

 

int main()
{list<int> a;a.push_back(1);a.push_front(0);for (auto it : a)cout << it;a.pop_front();for (auto it : a)cout << it;a.push_front(3);swap(a.front(),a.back());for (auto it : a)cout << it;swap(a.front(), a.back());for (auto it : a)cout << it;a.clear();cout << a.size();return 0;
}

迭代器失效

只有删除某个节点后，迭代器的位置还指向被删除节点时候才失效 

模拟实现 

 

#include<iostream>
using namespace std;namespace mylist
{template<class T>struct ListNode{ListNode(const T& val = T()):_val(val),_pPre(nullptr),_pNext(nullptr){}ListNode<T>* _pPre;ListNode<T>* _pNext;T _val;};template<class T, class Ref, class Ptr>class ListIterator{typedef ListNode<T>* PNode;typedef ListIterator<T, Ref, Ptr> Self;public:PNode node(){return _pNode;}ListIterator(PNode pNode = nullptr):_pNode(pNode){}ListIterator(const Self& l):_pNode(l._pNode){}T& operator*(){return _pNode->_val;}T* operator->(){return _pNode;}Self& operator++(){_pNode = _pNode->_pNext;return *this;}Self operator++(int){Self p = *this;_pNode = _pNode->_pNext;return Self(p);}Self& operator--(){_pNode = _pNode->_pPre;return *this;}Self& operator--(int){Self p = *this;_pNode = _pNode->_pPre;return Self(p);}bool operator!=(const Self& l) const{return _pNode != l._pNode;}bool operator==(const Self& l) const{return _pNode == l._pNode;}private:PNode _pNode;};template<class Iterator, class Ref, class Ptr>struct Reverse_iterator{typedef Reverse_iterator<Iterator, Ref, Ptr> Self;Reverse_iterator(Iterator it):_it(it){}Ref operator*(){Iterator t(_it);return *t;}Ptr operator->(){return &(operator*());}//// 迭代器支持移动Self& operator++(){Self temp(*this);--_it;return temp;}Self operator++(int){Self temp(*this);--_it;return temp;}Self& operator--(){++_it;return *this;}Self operator--(int){Self temp(*this);++_it;return temp;}bool operator!=(const Self& l) const{return _it != l._it;}bool operator==(const Self& l) const{return _it != l._it;}Iterator _it;};template<class T>class list{typedef ListNode<T> Node;typedef Node* PNode;public:typedef ListIterator<T, T&, T*> iterator;typedef ListIterator<T, const T&, const T&> const_iterator;typedef Reverse_iterator<iterator, const T&, const T*> const_Reverse_iterator;typedef Reverse_iterator<iterator,T&,T*> Reverse_iterator;public:list(){CreateHead();}list(int n, const T& value = T()){CreateHead();while(n--)push_front(value);}template <class Iterator>list(Iterator first, Iterator last){CreateHead();while (first != last){push_back(*first);first++;}}list(const list<T>& l){CreateHead();for (auto it : l){push_back(it);}}list<T>& operator=(const list<T>& l){list(l);}~list(){clear();delete _pHead;_pHead = nullptr;}///// List Iteratoriterator begin() { return iterator(_pHead->_pNext); }iterator end() {return iterator(_pHead);};const_iterator begin() const { return const_iterator(_pHead->_pNext); }const_iterator end() const { return const_iterator(_pHead); }Reverse_iterator rbegin(){return Reverse_iterator(--end());}Reverse_iterator rend(){return Reverse_iterator(--begin());}const_Reverse_iterator rbegin()const{return const_Reverse_iterator(--end());}const_Reverse_iterator rend()const{return const_Reverse_iterator(--begin());}///// List Capacitysize_t size()const{size_t s = 0;const_iterator it = this->begin();while (it != this->end()){it++;s++;}return s;}bool empty()const{return _pHead == _pHead->_pNext;}// List AccessT& front() { return _pHead->_pNext->_val; }const T& front()const { return _pHead->_pNext->_val; }T& back() { return _pHead->_pPre->_val; }const T& back()const { return _pHead->_pPre->_val; }// List Modifyvoid push_back(const T& val) { insert(end(), val); }void pop_back() { erase(--end()); }void push_front(const T& val) { insert(begin(), val); }void pop_front() { erase(begin()); }// 在pos位置前插入值为val的节点iterator insert(iterator pos, const T& val){PNode tmp = new Node(val);tmp->_pNext = pos.node();tmp->_pPre = pos.node()->_pPre;pos.node()->_pPre->_pNext = tmp;pos.node()->_pPre = tmp;return iterator(tmp);}// 删除pos位置的节点，返回该节点的下一个位置iterator erase(iterator pos){PNode it = pos.node()->_pNext;PNode p = pos.node();p->_pNext->_pPre = p->_pPre;p->_pPre->_pNext = p->_pNext;delete p;return iterator(it);}void clear(){while (_pHead != _pHead->_pNext){pop_front();}}void swap(list<T>& l){PNode tmp = l._pHead;l._pHead = _pHead;_pHead = tmp;}private:void CreateHead(){_pHead = new Node;_pHead->_pNext = _pHead;_pHead->_pPre = _pHead;}PNode _pHead;};
};