用类去封装一个可变长数组(Vector)

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<cctype>
#include<fstream>
using namespace std;
template<typename T>
class Vector
{
private:
	T* p;
	int size;
public:
	Vector() {
		size = 0;
	}
	Vector(int psize) :size(psize) {
		delete[]p;
		p = new T[psize];
	}
	Vector(const Vector& tr) {
		if (tr.size == 0) {
			delete[]p;
			p = NULL;
			return;
		}
		delete[]p;
		p = new T[tr.size];
		memcpy(p, tr.p, sizeof(T) * tr.size);
		size = tr.size;
	}
	~Vector() {}
	T& operator[](int i) {
		return p[i];
	}
	Vector& operator=(const Vector& tr) {
		if (tr.size == 0) {
			delete[]p;
			p = NULL;
			return *this;
		}
		delete[]p;
		p = new T[tr.size];
		memcpy(p, tr.p, sizeof(T) * tr.size);
		return *this;
	}
	void push_back(T ele) {
		if (p == NULL) {
			p = new T[1];
			p[size++] = ele;
		}
		else {
			T* ptr = new T[size + 1];
			memcpy(ptr, p, sizeof(T) * (size));
			ptr[size++] = ele;
			delete[]p;
			p = ptr;
		}
	}
	int getsize() {
		return size;
	}
};
int main()
{
	Vector<int>v1,v2;
	cout << v1.getsize() << endl;
	for (int i = 0; i < 5; i++) {
		v1.push_back(i);
	}
	v2 = v1;
	for (int i = 0; i < 5; i++) {
		cout << v2[i]<<" ";
	}
	cout << endl;
	Vector<string>vv(100);
	vv[10] = "hello";
	cout << vv[10];

}