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#include <iostream>
using namespace std;
struct DATE
{
int year, month, day; //三个变量的内存地址是连续的
DATE(int year, int month, int day) : year(year), month(month), day(day){}
};
int cmp(const DATE x, const DATE y, int index = 0)
{
void *px = (void*)&x, *py = (void*)&y;
//依据index取year, month， day
int *temp_x = ((int*)px + index);
int *temp_y = ((int*)py + index);
int m = 0, n = 0;
//&&短路+递归
//当m==0时表示当前比较的单位相等，所以当当前比较单位不是日时，递归比较下一级单位，同时逻辑运算置零，
//返回当前单位之差m或者下一级单位比较结果n
return ((m = (*temp_x - *temp_y)) == 0 && index != 2 && (n = cmp(x, y, index + 1)) && 0) + m + n;
}
int main()
{
DATE x(2, 12, 1), y(2, 12, 1);
cout << cmp(x, y) << endl;
return 0;
}