实验12：Problem A: 你会定义类吗？

#include<iostream>
using namespace std;
class Demo{
public:
    int x;
    Demo(int a=0):x(a){cout<<"A data "<<x<<" is created!"<<endl;}
    ~Demo(){cout<<"A data "<<x<<" is erased!"<<endl;}
    void show(){cout<<"This is data "<<x<<endl;}
};
int main()
{
    Demo tmp(10), tmp2;
    int d;
    cin>>d;
    Demo tmp3(d);

    tmp.show();
    tmp2.show();
    tmp3.show();
    return 0;
}