void judgescore ()
     {
                  int score ;
                   printf("请输入一个分数：");

                 scanf ("%d",&score);

           if (score<0 && score >100)
           {
               printf("输入错误！");
           }
           else  
          {              
               printf  ("分数在0~100之内！\n");      
              if (score<60)
              {
                  printf("差！");
              }
              else
              {
                  if (score<70)
                  {
                      printf("及格！");
                  }
                  else
                  {
                      if (score<80)
                      {
                          printf("中！");
                      }
                      else     
                      {
                          if(score<90)
                          {
                              printf("良！");
                          }
                          else
                          {
                              printf("优！");
                          }
                      }
                  }
              }
           }

     }

我说的是判断出错的那一行代码 有问题

我已经连续写了 4天的代码，感觉越写越简单了，感觉这些怎么简单的代码，以前学起来怎么这么难