有五个学生，每个学生有3门课的成绩，从键盘输入以上数据（包括学生号，姓名，三门课成绩），计算出
　　　平均成绩，况原有的数据和计算出的平均分数存放在磁盘文件"stud"中。


#include <stdio.h>
    struct  student
     { char num[6];
       char name[8];
       int  score[3];
       float avr;
     }  stu[5];
     void main()
     {int i,j,sum;
     FILE *fp;
     for(i=0;i<5;i++)
     {   
         printf("pleased input NO.%d score:\n",i);   

         scanf("%",&stu[i].score[j]);
         printf("stuNO:");
             scanf("%s",stu[i].num);
         printf("name:");
            scanf("%s",stu[i].name);
            sum=0;
            for(j=0;j<3;j++)
            {  printf("score %d.",j+1);
            sum+=stu[i].score[j];}
             stu[i].avr=sum/3.0;
     }
     fp=fopen("stud","w");
     for(i=0;i<5;i++)
         if(fwrite(&stu[i],sizeof(struct student),1,fp)!=1)
             printf("file write error");
         fclose(fp);
     }
     

  scanf("%d",&stu[i].score[j]);//少了d  
  LZ在调试一下

#include <stdio.h>
    struct  student
     { int num[6];
       char name[8];
       int  score[3];
       float avr;
     }stu[5];
     void main()
{
     int i,j,sum;
     FILE *fp;
        for(i=0;i<5;i++)
        {   
         printf("please input NO.%d score:\n",i);   
         for(j=0;j<3;j++)
         scanf("%d",&stu[i].score[j]);
         printf("stuNO:");
             scanf("%d",stu[i].num);
         printf("name:");
            scanf("%s",stu[i].name);
            sum=0;
            for(j=0;j<3;j++)
            {                           //printf("score %d.",j+1);
            sum+=stu[i].score[j];}
              stu[i].avr=sum/3.0;
        }
     fp=fopen("stud","w");
     if(fp==NULL)
         printf("cannot open file\n");
     else
     for(i=0;i<5;i++)
         if(fwrite(&stu[i],sizeof(struct student),1,fp)!=1)
             printf("file write error\n");
         fclose(fp);
}