#include<stdio.h>
void main()
{
    float s;
    int grade;
    scanf("%d",s);
    do
    {
        printf("\n输入的分数有错误");
    }
    while(s>100||s<0);
        switch((int)(s/10))
        {
            case 10:grade='A';break;
            case 9:grade='B';break;
            case 8:grade='C';break;
            case 7:grade='D';break;
            case 6:
            case 5:
            case 4:
            case 3:
            case 2:
            case 1:
            case 0:grade='E';break;
        }
        printf("成绩是%5.1f,相应等级是%c\n",s,grade);
            
   
    这是我写的程序，用2010编译的，没有语法错误。只不过编译的时候出现这个对话框

#include<stdio.h>
void main()
{
    float s;
    int grade;
    scanf("%f",&s);
   
    if(s > 100 || s < 0)
        printf("\n输入的分数有错误");
   
    else
    {
        switch((int)(s/10))
        {
            case 10:grade='A';break;
            case 9:grade='B';break;
            case 8:grade='C';break;
            case 7:grade='D';break;
            case 6:
            case 5:
            case 4:
            case 3:
            case 2:
            case 1:
            case 0:grade='E';break;
        }
        printf("成绩是%5.1f,相应等级是%c\n",s,grade);
    }   
}        

第六行  scanf 那里忘记了个&    // scanf("%d",&s);
最后少了个 }
第二行改成 int main（）

这样就没报错-.-