成绩转换问题

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<math.h>
 4 #include<string.h>
 5 int main()
 6 {
 7     int score;
 8     while (scanf("%d",&score)!=EOF)
 9     {
10         if (score>=0)
11         switch(score/10)
12         {
13             case 0: printf("E\n"); break;
14             case 1: printf("E\n"); break;
15             case 2: printf("E\n"); break;
16             case 3: printf("E\n"); break;
17             case 4: printf("E\n"); break;
18             case 5: printf("E\n"); break;
19             case 6: printf("D\n"); break;
20             case 7: printf("C\n"); break;
21             case 8: printf("B\n"); break;
22             case 9: printf("A\n"); break;
23             default: if (100==score)
24                         printf("A\n");
25                     else
26                         printf("Score is error!\n"); break;
27         }
28         else printf("Score is error!\n");
29     }
30     return 0;
31 }