C++vector模拟实现

这段代码依靠_start,_finish和_capicity三个指针来维护vector的线性空间

#include<iostream>
#include<assert.h>
using namespace std;


template<typename T>
class Myvector
{
public:
	typedef T Vtype;
	typedef Vtype* iterator;
	typedef const Vtype* Constiterator;
	//构造函数
	Myvector():_start(NULL),_finish(NULL),_capicity(NULL){}
	~Myvector()
	{
		if (NULL != _start)
		{
			delete[]_start;
		}
		_finish = _capicity = _start;
	}
	//push_back
	void push_back(T element)
	{
		resize();
		*_finish = element;
		_finish++;
	}
	//pop_back
	void pop_back()
	{
		assert(_start != _finish);
		_finish--;
	}
	//size()
	size_t size()
	{
		size_t s = _finish - _start;
		return s;
	}
	//capcity()
	size_t capicity()
	{
		size_t cap = _capicity - _start;
		return cap;
	}
	//begin()
	iterator begin()
	{
		return _start;
	}
	//end()
	iterator end()
	{
		return _finish;
	}
	T operator[](int index)
	{
		assert(_start+index<_finish);
		return _start[index];
	}
	
	void resize()
	{
		if (_finish==_capicity)
		{
			size_t _size = _finish - _start;
			size_t cap = 2 * _size + 3;
			T* newelement = new T[cap];
			for (unsigned int i = 0; i < _size; i++)
			{
				newelement[i] = _start[i];
			}
			delete[]_start;
			_start = newelement;
			//末尾元素地址
			_finish = _start + _size;
			//容量大小
			_capicity = _start + cap;
		}
	}

private:

	iterator _start;
	iterator _finish;
	iterator _capicity;

};


int main(const int argc,const char*argv[])
{
;
Myvector<int>arr;
arr.push_back(1);
arr.push_back(2);
arr.push_back(3);
arr.push_back(4);
arr.push_back(5);
cout << arr.size() << " " << arr.capicity() << endl;
Myvector<int>::iterator it = arr.begin();
while (it != arr.end())
{
	cout << *it << " ";
	it++;
}
for (int i = 0; i < arr.size(); i++)
	arr.pop_back();

}