std::vector的核心框架接口的模拟实现bit::vector

#pragma once
#include<iostream>
#include<assert.h>
#include<string>
#include<algorithm>
#include<vector>using std::cout;
using std::endl;namespace bit
{template<class T>class vector{public:typedef T* iterator;typedef const T* const_iterator;iterator begin(){return _start;}iterator end(){return _finish;}const_iterator begin()const{return _start;}const_iterator end()const{return _finish;}vector(){}vector(const vector<T>& v){reserve(v.capacity());for (auto& e : v){push_back(e);}}vector(std::initializer_list<T> il){size_t n = il.size();reserve(n * sizeof(T));for (auto e : il){push_back(e);}}//类模板的成员函数可以是函数模板template<class InputIterator>vector(InputIterator first, InputIterator last){while (first < last){push_back(*first);++first;}}vector(size_t n, const T& val = T()){resize(n, val);}vector(int n, const T& val = T()){resize(n, val);}void swap(vector<T> v){std::swap(_start, v._start);std::swap(_finish, v._finish);std::swap(_endofstorage, v._endofstorage);}// 1.传统写法//vector<T>& operator=(const vector<T>& v)//{//	_start = new T[v.capacity()*sizeof(T)];//	memcpy(_start, v._start, v.size());//	_finish = _start + v.size();//	_endofstorage = _start + v.capacity();//}// 2.现代写法vector<T>& operator=(vector<T> v){swap(v);}~vector(){delete[] _start;_start= _finish = _endofstorage = nullptr;}size_t size()const{return _finish - _start;}T& operator[](size_t pos){assert(pos < size());return _start[pos];}const T& operator[](size_t pos)const{assert(pos < size());return _start[pos];}size_t capacity()const{return _endofstorage - _start;}void reserve(size_t n){if (n > capacity()){T* tmp = new T[n];size_t old_size = size();// 不能用memcpy会导致T浅拷贝//memcpy(tmp, _start, size() * sizeof(T));for (size_t i = 0; i < old_size; i++){tmp[i] = _start[i];}delete[] _start;_start = tmp;_finish = tmp + old_size;_endofstorage = tmp + n;}}//1.版本void resize(size_t n, const T& val = T()){if (n > size()){reserve(n);// 插入while (_finish < _start + n){*_finish = val;++_finish;}}else{// 删除_finish = _start + n;}}//2.版本//void resize(size_t n, const T& val = T())//{//	if (n < size())//	{//		_finish = _start + n;//	}//	else//	{//		size_t i = n - size();//		for (; i << n > 0; i--)//		{//			push_back(val);//		}//	}//}void push_back(const T& val){/*if (size() == capacity()){reserve(capacity() == 0 ? 4 : 2 * capacity());}*_finish = val;++_finish;*/insert(_finish, val);}void pop_back(){/*assert(!empty());--_finish;*/erase(--end());}bool empty(){return _start==_finish;}//1. 版本void insert(iterator pos, const T& val){assert(pos >= _start);assert(pos <= _finish);if (size() == capacity()){size_t len = pos - _start;reserve(capacity() == 0 ? 4 : 2 * capacity());// 如果扩容要更新pos(迭代器失效)pos = _start + len;}iterator it = _finish -1;while (it >= pos){*(it + 1) = *it;--it;}*pos = val;++_finish;}//2. 版本//void insert(iterator pos, const T& val)//{//	assert(pos >= _start);//	assert(pos <= _finish);//	size_t len = _finish - pos;//	size_t n = pos - _start;//	if (size() == capacity())//	{//		reserve(capacity() == 0 ? 4 : 2 * capacity());//	}//	pos = _start + n;//	T* tmp = new T[len*sizeof(T)];//	memcpy(tmp, pos, len);//	memcpy(pos + 1, tmp, len);//	delete[]tmp;//	*pos = val;//	++_finish;//}iterator erase(iterator pos){assert(pos >= _start);assert(pos < _finish);iterator it = pos + 1;while (it < _finish - 1){*it = *(it + 1);it++;}--_finish;return pos;}private:iterator _start=nullptr;iterator _finish=nullptr;iterator _endofstorage=nullptr;};template <class T>void print_vector(const vector<T>& v){for (int i = 0; i < v.size(); i++){cout << v[i] << " ";}cout << endl;这样写编译报错,编译时vector<int>和没有实例化编译器不敢进入模板取,就不知道const_iterator时内部类, 还是静态成员变量, 还是typedef定义的类型 vector<int>::const_iterator it = v.begin();解决办法:1. 在最前面加上typename(不能用class)typename vector<int>::const_iterator it = v.begin();		  2. 直接用auto//auto it = v.begin();//while (it != v.end())//{//	cout << *it << " ";//	++it;//}//cout << endl;//for (auto e : v)//{//	cout << e << " ";//}}
}