#include<stdio.h>
main()
{
    int score=0;
    printf("please input your score:\n");
        scanf("%d",&score);
        if((score>100)||(score<0))
            printf("please input your score again!\n");
        switch(score/10)
        {
           case 10:
               printf("the score is A.\n")
               break；
           case 9:
               printf("the score is A.\n")
               break；
           case 8:
               printf("the score is B.\n")
               break；
           case 7:
               printf("the score is C.\n")
               break；
           case 6:
               printf("the score is D.\n")
               break；
           default:
               printf("the score is E.\n")
        }
}

#include<stdio.h>
main()
{
    int score;
    printf("please input your score:\n");
        scanf("%d",&score);
        if((score>100)||(score<0))
            printf("please input your score again!\n");
        switch(score/10)
        {
           case 10:
               printf("the score is A.\n");//每个printf后面要加“ ;”
               break;//你的之前都是中文的 呵呵 马虎了！
           case 9:
               printf("the score is A.\n");
               break;
           case 8:
               printf("the score is B.\n");
               break;
           case 7:
               printf("the score is C.\n");
               break;
           case 6:
               printf("the score is D.\n");
               break;
           default:
               printf("the score is E.\n");
        }
} 

这个c语言是课本上的，但是输入后提示错误，和书上一样的，请问哪里是中文的啊，有点不太明白

这个我是用另一种方法做的，提示一个错误，就是在“int:x=100，&&，x<100；”这个地方错误


#include<stdio.h>
main()
{
    int: x=100,&&,x<100；
         else if(x<=100,&&,x>=90)
              printf("a\n")
              else if(x<90,&&,x>=80)
                   printf("b\n")
                   else if(x<80,&&,x>=70)
                        printf("c\n")
                        else if(x<70,&&,x>=60)
                             printf("d\n")
                                else if(x<0)
                                  printf("Error\n")
}

break前有；
加上头文件#include <math.h>
最后的default语句最后也加上break比较好
下面是我改了之后的代码在VC6.0中运行成功。
#include<stdio.h>
#include<math.h>
main()
{
    int score;
    printf("please input your score:\n");
        scanf("%d",&score);
        if((score>100)||(score<0))
            printf("please input your score again!\n");
        switch(score/10)
        {
           case 10:
               printf("the score is A.\n");
               break;
           case 9:
               printf("the score is A.\n");
               break;
           case 8:
               printf("the score is B.\n");
               break;
           case 7:
               printf("the score is C.\n");
               break;
           case 6:
               printf("the score is D.\n");
               break;
           default:
               printf("the score is E.\n");
               break;
        }
}
如果你是在WIN-tc中编译可能最后还要加一句getch（）；

你照着输  丢掉了很多东西！！比如 你看 printf 后面  一条语句结束 要加“;”(分号，一定要在英文输入法的状态下)！！
你的 printf 后面丢了分号。同时break语句后面你的分号 是在中文输入法的状态下输入的！！

哦，明白了，我试试啊，谢谢啊！

至于你说的if-else结构的问题
它的格式应该是
if(表达式1)
语句1
else if(表达式2)
语句2
.
.
.
else if(表达式n)
语句n
else(表达式n+1)
语句n+1

你的结构有问题
还有你的变量声明 也有问题
还是先看看书吧  一遍不行 就多遍！！加油~~

#include<stdio.h>
void main()
{
    int x;
    scanf("%d",&x);
          if(x<=100 && x>=90)
              printf("a\n");
              else if(x<90 && x>=80)
                   printf("b\n");
                   else if(x<80 && x>=70)
                        printf("c\n");
                        else if(x<70 && x>=60)
                             printf("d\n");
                            else if(x<60&&x>0)
                                printf("e\n");
                                  else
                                  printf("Error\n");
} 

正确的              #include<stdio.h>
main()
{
    int score=0;
    printf("please input your score:\n");
        scanf("%d",&score);
        if((score>100)||(score<0))
            printf("please input your score again!\n");
        switch(score/10)
        {
           case 10:
               printf("the score is A.\n") ;   break;
            
           case 9:
               printf("the score is A.\n") ;  break;
              
           case 8:
               printf("the score is B.\n") ;  break;
               
           case 7:
               printf("the score is C.\n") ;  break;
              
           case 6:
               printf("the score is D.\n") ;  break;
            
           default:
               printf("the score is E.\n");
        }
}