STL-Vector

// testVector.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<iostream>
using namespace std;

template<typename T>
class MyVector {
public:
	typedef T value_type;
	typedef value_type* iterator; //其实迭代器就是传进来参数的指针，这样设计就可以让用户不用知道是什么类型直接使用
	MyVector():start(nullptr),finish(nullptr),end_vector(nullptr){}
	T& front() {
		return *start;
	}
	T& back() {
		return *(finish - 1);
	}
	T* begin() {
		return start;
	}
	T* end() {
		return finish;
	}
	T& operator[](int index) {
		return data[index];
	}
	void push_back(const T& value) {           //如果还有空间就把新元素添加至末尾
		if (finish != end_vector) {
			*(finish++) = value;
		}
		else {                    //没有空间的情况下，开辟一个新的空间并把之前的内容移动过来。
 			size_t old_size = end_vector - start;
			size_t size = (old_size == 0) ? 1 : (end_vector - start) * 2;
			T *newdata = new T[size];
			memmove(newdata, data, (end_vector - start)*sizeof(T));
			delete[] data;
			data = newdata;
			start = newdata;
			finish = start + old_size;
			end_vector = data + size;
			*(finish++) = value;
		}
	}
	void pop_back() {
		 finish--;
	}
	~MyVector() {
		delete[]data;
	}
private:
	T *data;
	T *start;
	T *finish;
	T *end_vector;
};
struct A {
	int f;
public:
	A(int r) :f(r) {}
	A()
	{
		f = 1;
	}
};
int main() {
	MyVector<A> v;
	v.push_back(A(2));
	v.push_back(A(3));
	v.push_back(A(4));
	v.push_back(A(5));
	v.push_back(A(6));
	MyVector<A>::iterator it = v.begin();
	MyVector<A>::iterator end = v.end();
	for (; it != end; it++)
		printf("%d\n", it->f);


}