C++模拟實作vector

代碼如下：

#include<iostream>
#include<string>
using namespace std;
template<class T>
class Vector
{
public:
	typedef T* itreator;//正向可修改疊代器
	typedef const T* const_itreator;//正向不可修改疊代器
	Vector()
		:_start(nullptr)
		, _finish(nullptr)
		, _endOfStorage(nullptr)
	{}
	itreator begin()
	{
		return _start;
	}
	itreator end()
	{
		return _finish;
	}
	const_itreator begin() const
	{
		return _start;
	}
	const_itreator end() const
	{
		return _finish;
	}
	size_t size()//擷取目前有效元素個數
	{
		return _finish - _start;
	}
	size_t capacity()//擷取目前容量
	{
		return _endOfStorage - _start;
	}
	void pushback(const T& val)//pushback的尾插
	{
		//先檢查容量
		if (_finish == _endOfStorage)//需要擴容
		{
			size_t newC = capacity() == 0 ? 1 : 2 * capacity();
			reserve(newC);
		}
		*_finish = val;
		_finish++;
	}
	void reserve(size_t n)//reserve擴容
	{
		if (n > capacity())
		{
			int sz = size();
			T *tmp = new T[n];
			if (_start != nullptr)
			{
				for (int i = 0; i < sz; i++)//深拷貝，如果用memcpy是一個淺拷貝，會導緻二次釋放問題
				{
					tmp[i] = _start[i];
				}
				//delete[] _start;
			}
			_start = tmp;
			_finish = _start + sz;
			_endOfStorage = _start + n;
		}
	}
	T& operator[](size_t pos)
	{
		return _start[pos];
	}
	void resize(size_t n,const T& val)
	{
		if (n > capacity())
		{
			reserve(n);
		}
		if (n > size())
		{
			while (_finish != _start + n)
			{
				*_finish = val;
				++_finish;
			}
		}
		_finish = _start + n;
	}
	void insert(itreator pos, const T& val)//insrt插入
	{
		if (pos >= _start && pos <= _finish)
		{
			if (_finish == _endOfStorage)
			{
				int len = pos - _start;
				size_t newC = capacity() == 0 ? 1 : 2 * capacity();
				reserve(newC);
				pos = _start + len;
			}
			itreator end = _finish;
			while (pos != end)
			{
				*end = *(end - 1);
				end--;
			}
			*pos = val;
			_finish++;
		}
	}
	iterator erase(iterator pos)//删除疊代器指向的pos位置
	{
		if (pos >= begin() && pos < end())
		{
			iterator begin = pos + 1;
			while (begin != _finish)
			{
				*(begin - 1) = *begin;
				begin++;
			}
			--_finish;
			return pos;
		}
	}
	void pop_back()//尾删
	{
		if (size() > 0)
		{
			erase(end() - 1);
		}
	}
	Vector(const Vector<T>& v)//Vector泛型拷貝構造
		:_start(new T[capacity()])
		, _finish(_start + v.size())
		, _endOfStorage(_start + v.capacity());
	{
		//進行深拷貝
		for (int i = 0; i < v.size(); i++)
		{
			_start[i] = v[i];
		}
	}
	Vector<T>& operator=(Vector<T> v)
	{
		Swap(v);
		return *this;
	}
	void Swap(Vector<T>& v)
	{
		swap(_start, v._start);
		swap(_finish, v._finish);
		swap(_endOfStorage, v.endOfStorage);
	}
private:
	T *_start;
	T *_finish;
	T *_endOfStorage;
};
int main()
{
	system("pause");
	return 0;
}