c++类模板实现一个c++ STL里面的一个顺序容器 vector 向量容器

#include <iostream>
/*
类模板=》实现一个c++ STL里面的一个顺序容器 vector 向量容器

*/

template<typename T>
class vector
{
public:
	vector(int size = 10)
	{
		_first = new T[size];
		_last = _first;
		_end = _first + size;
	}
	~vector()
	{
		delete[] _first;
		_first = _last = _end = nullptr;
	}
	vector(const vector<T> &rhs)
	{
		int size = rhs._end - rhs._first;
		_first = new T[size];
		int len = rhs._last - rhs._first;
		for (int i = 0;i < len;++i)
		{
			_first[i] = rhs._first[i];
		}
		_last = _first + len;
		_end = _first + size;
	}
	vector<T>& operator=(const vector<T>& rhs)
	{
		if (this == &rhs)
		{
			return *this;
		}
		delete[] _first;
		int size = rhs._end - rhs._first;
		_first = new T[size];
		int len = rhs._last - rhs._first;
		for (int i = 0;i < len;++i)
		{
			_first[i] = rhs._first[i];
		}
		_last = _first + len;
		_end = _first + size;
        return *this;
	}
	void push_back(const T & val)//向容器末尾添加元素
	{
		if (full())
		{
			expand();
		}
		*_last++ = val;
	}
	void pop_back()//从容器末尾删除元素
	{
		if (empty())
		{
			return;
		}
		--_last;
	}
	T back() const //返回容器末尾的元素值
	{
		return *(_last - 1);
	}
	bool full() const{ return _last == _end; }
	bool empty() const { return _first == _last; }
	int size() const { return _last; }
private:
	T* _first;//指向数组起始的位置
	T* _last;//指向数组中有效元素的后继位置
	T* _end;//指向数组空间的后继位置
	void expand()// 容器的二倍扩容
	{
		int size = _end - _first;
		T* ptmp = new T[2 * size];
		for (int i = 0;i < size;++i)
		{
			ptmp[i] = _first[i];
		}
		delete[] _first;
		_first = ptmp;
		_last = _first + size;
		_end = _first + 2 * size;
	}
};

int main()
{
	vector<int> vec;
	for (int i = 0;i < 10;++i)
	{
		vec.push_back(rand() % 100);
	}
	//vec.pop_back();
	while (!vec.empty())
	{
		std::cout << vec.back() << " ";
		vec.pop_back();
	}
	std::cout << std::endl;
}

输出信息如下：

64 62 58 78 24 69 0 34 67 41