求大佬帮忙解答

最近学习了联合体遇到了这样一个题目 希望大佬能帮忙解答下
union MyUnion1
{
double d;
float c;
int a;
short n[4];
};
int main()
{
MyUnion1 u1;
u1.d = 100;
cout << u1.d << endl;
cout << u1.a << endl;
cout << u1.c << endl;
cout << u1.n[0] << endl;
cout << u1.n[1] << endl;
cout << u1.n[2] << endl;
cout << u1.n[3] << endl;
}