关于位段的一道题

#include
#include
int main(){
	unsigned char arr[4];
	struct str{//位段
		unsigned char a;
		unsigned char b : 1;
		unsigned char c : 2;
		unsigned char d : 3;
	}*ps;
	ps = (struct str*)arr;
	memset(arr, 0, 4);
	ps->a = 2;
	ps->b = 3;
	ps->c = 4;
	ps->d = 5;
	printf("%02x %02x %02x %02x", arr[0], arr[1], arr[2], arr[3]);
	return 0;
}