#include <iostream>
using namespace std;
typedef int &Age; // Age类型是int的引用,Age是int的别名,指向同一数据
typedef int Year; // Year类型是int的变量,Year和int是分开的变量,互不相关,但是类型相同
int main() {
int a = 10;
Age age = a;
Year year = a;
a = 100;
cout << a << endl;
cout << age << endl; // age随a改变
cout << year << endl; // year不随a改变
return 0;
}