C++中vector的模拟实现

一、vector.h

#pragma once
#include<iostream>
#include<assert.h>
#include<string>
namespace bit
{
	template<class T>
	class vector
	{
	public:
		// Vector的迭代器是一个原生指针
		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;
		}
		// construct and destroy
		vector()
			:_start(nullptr),_finish(nullptr),_endOfStorage(nullptr)
		{}
		vector(int n, const T& value = T())
		{
			reserve(n);
			for (size_t i = 0; i < n; i++)
			{
				push_back(value);
			}
		}
		template<class InputIterator>
		vector(InputIterator first, InputIterator last)
		{
			while (first != last)
			{
				push_back(*first);
				first++;
			}
		}
		vector(const vector<T>& v)
		{
			reserve(v.capacity());
			for (auto& e : v)
			{
				push_back(e);
			}
		}
		vector<T>& operator= (vector<T> v)
		{
			swap(v);
			return *this;
		}
		~vector()
		{
			delete[] _start;
			_start = _finish = _endOfStorage = nullptr;
		}
		// capacity
		size_t size() const
		{
			return _finish - _start;
		}
		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();
				//memcpy(tmp, _start, size() * sizeof(T));  //如果用memcpy，string等类的拷贝是浅拷贝，_start析构会将空间释放掉