#include <iostream>
using namespace std;
int main(void)
{
int x = 3;
//定義引用，y是x的引用
int &y=x;
//打印x和y的值
cout<<x<<endl;
cout<<y<<endl;
//修改y的值
y = 20;
//再次打印x和y的值
cout<<x<<","<<y<<endl;
return 0;
}
