C语言学的明白的请进~

(147)C
(98)D
(39)
int main()
{int day,x1,x2;
day=0;x1=1020;
while(x1>0)
{x2=x1/2-2; x1=x2;day++;}
printf("day=%d\n",day);
}
(60)
sizeof(a)==16
sizeof(a.share)==4