#include<stdio.h>
int main()
{
    char grade;
    float score;
    printf("输入你的成绩:");
    scanf("%f",&score);
    while(score>100||score<0)
    {
        printf("错误！");
        scanf("%f",&score);
    }
    switch((int)(score/10))
    {
        case10:
        case9:grade='A';break;
        case8:grade='B';break;
        case7:grade='C';break;
        case6:grade='D';break;
        case5:
        case4:
        case3:
        case2:
        case1:
        case0:grade='E';break;
    }
    printf("%c",grade);
    return 0;
}

哇，谢谢了，这一点小差别根本没注意到啊

谢谢谢~