if判断闰年的程序问题

Question

#include <stdio.h>int main() {     int year,month,day,sum; char a;       loop: do{  printf("input year,month,day\n");  scanf("%d.%d.%d",&year,&month,&day);  if(month>=1&&month<=12&&day>=1&&day<=31)   {    switch(month)    {    case 1:sum=day;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 2:sum=day+31;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 3: if(year%400==0||(year%4==0&&year%100!=0))    { sum=day+60;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;}else { sum=day+59;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;}    case 4:sum=day+90;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 5:sum=day+120;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 6:sum=day+151;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 7:sum=day+181;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 8:sum=day+212;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 9:sum=day+243;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 10:sum=day+273;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 11:sum=day+304;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    case 12:sum=day+334;printf("%d年%d月%d日是该年的第%d天\n",year,month,day,sum);break;    default:printf("一年只有12个月哟~\n");break;     }    printf("Do you want to continue?y/n\n");     scanf(" %c",&a);     } else {  printf("Error\n");  goto loop; } }while(a=='y'||a=='Y'); return 0;}无论闰年非闰年每年的8月8号都显示是220天，其实闰年是221天，也就是判断不了闰年，求解

Answer 1

switch中，你只在三月份的时候判断了一下该年是否为闰年，后面的月份你就不管啦？！