由于我们之前已经详细讲解了string接口，而vector接口大都在string上有，所以大家只需自行翻阅前面文章就可以明白接口的使用了，所以，这里我们只实现vector，注意：vector会有迭代器失效的情况，大家一定要仔细看看代码。

#pragma once
#include <assert.h>
#include <iostream>
#include <string.h>
namespace cx
{//模板类template<class T>class vector{public:typedef T* iterator;typedef const T* const_iterator;//构造函数:vector(){}//传统写法/*vector(const vector<T>& v){_start = new T[v.capacity()];memcpy(_start, v._start, v.size() * sizeof(T));_finish = _start + v.size();_endofstorage = _start + v.capacity();}*///现代写法：vector(const vector<T>& v){reserve(v.capacity());for (const auto e : v){*_finish = e;_finish++;}}vector(size_t n, const T& val = T()){resize(n,val);}/*template <class InputIterator>vector(InputIterator first, InputIterator last){while (first != last){push_back(*first);first++;}}*///析构函数~vector(){if (_start){delete[] _start;_start = _finish = _endofstorage = nullptr;}}vector<T>& operator=(vector<T> v){swap(v);return *this;}//迭代器iterator begin(){return _start;}iterator end(){return _finish;}const_iterator begin()const{return _start;}const_iterator end()const{return _finish;}//计算大小size_t size()const {return end() - begin();}size_t capacity()const {return _endofstorage - _start;}//操作:bool empty() const{return _finish == _start;}void swap(vector<T>& v){std::swap(_start, v._start);std::swap(_finish, v._finish);std::swap(_endofstorage, v._endofstorage);}void reserve(size_t n){if (n > capacity()){size_t old = size();T* tmp = new T[n];if (_start){memcpy(tmp, _start, sizeof(T) * old);delete[] _start;}_start = tmp;_finish = _start + old;_endofstorage = _start + n;}}void push_back(const T x){//检查是否扩容if (_finish == _endofstorage){size_t newcapacity = capacity() == 0 ? 4 : 2 * capacity();reserve(newcapacity);}*_finish = x;_finish++;}void pop_back(){assert(size() > 0);_finish--;}T& operator[](size_t pos){assert(pos < size());return _start[pos];}T& operator[] (size_t pos) const{assert(pos < size());return _start[pos];}iterator insert(iterator pos, const T& val){assert(pos <= _finish && pos >= _start);if (_finish == _endofstorage){size_t len = pos - _start;reserve(capacity() == 0 ? 4 : 2 * capacity());pos = _start + len;}//memmove(pos + 1, pos, sizeof(T) * (_finish - pos));iterator end = _finish - 1;while (end >= pos){*(end + 1) = *(end);end--;}*pos = val;_finish++;return pos;}/*void insert(iterator pos, const T& x){//检查assert(pos >= _start);assert(pos <= _finish);if (_finish == _endofstorage){size_t len = pos - _start;reserve(capacity() == 0 ? 4 : 2 * capacity());//注意：pos位置也要改变pos = _start + len;}memmove(pos + 1, pos, sizeof(T) * (_finish - pos));*pos = x;_finish++;}*/iterator erase(iterator pos){assert(pos < _finish && pos >= _start);iterator it = pos + 1;while (it < _finish){*(it - 1) = *it;it++;}_finish--;return pos;}iterator erase(iterator first, iterator last){}void resize(size_t n, T val = T()){if (n > size()){reserve(n);while (_finish < _start + n){*_finish = val;_finish++;}}else{_finish = _start + n;}}T& front(){return *_start;}const T& front() const{*_start;}T& back(){return *_finish;}const T& back() const{return *_finish;}T& at(size_t pos){assert(pos < size());return _start[pos];}const T& at(size_t pos) const{assert(pos < size());return _start[pos];}void assign(size_t n, const T& val){assert(_start == _finish);reserve(n);while (_finish != _endofstorage){*_finish = val;_finish++;}}void clear(){resize(0);}private:iterator _start = nullptr;iterator _finish = nullptr;iterator _endofstorage = nullptr;};
}

最后，感谢大家的支持！