#include <iostream>
using namespace std;
int main(void)
{
int x = 3;
//定义引用，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 = 7;
//再次打印x和y的值
cout<<x<<endl;
coun<<y<<endl:
return 0;
}
