关于#c语言#的问题：注意：闰年的判别条件是该年年份能被4整除但不能被100整除、或者能被400整除

Question

代码运行只能计算闰年，计算不了平年帮看看哪里出错
#include<stdio.h>
int main()
{
int a,b,c,d,e,f,g;
f=0;
scanf("%d/%d%/%d",&a,&b,&c);
for(d=1;d<b;d++)
{
switch(d)
{
case 1: e=31;
break;
if((a%4==0&&a%100!=0)||(a%400==0))
{
case 2: e=29;
break;
}
else
{
e=28;
break;
}
case 3: e=31;
break;
case 4: e=30;
break;
case 5: e=31;
break;
case 6: e=30;
break;
case 7: e=31;
break;
case 8: e=31;
break;
case 9: e=30;
break;
case 10: e=31;
break;
case 11: e=30;
break;
case 12: e=31;
break;
}
f=f+e;
}
g=f+c;
printf("%d",g);
return 0;
}

Answer 1

case 2: 
if((a%4==0&&a%100!=0)||(a%400==0)) e=29;
else e=28;
break;