想不通啊，到底什么原因

顶一下

#include <stdio.h>
int main()
{
int a;
//loop:
printf("请输入分数：");
scanf("%d",&a);
switch ("%d", (int)a / 10)
{
case 0:
case 1:
case 2:printf("等级D\n");break;
case 3:
case 4: printf("等级C\n");break;
case 5:
case 6:printf("等级B\n");break;
case 7:
case 8: printf("等级A\n");break;
case 9:
case 10: printf("等级S\n");break;
default:printf("输入错误\n");break;
}
getchar();
//goto loop;
return 0;
}