问题描述

将第7题结果仍存入原有的stu_sort文件而不另建立新文件。

样例

NO.:160 name :Hua
score1,score2,score3:78,89,91 
original data:
140 Ma 100 99 98 99.00 
101  Li 90 89 88 89.00 
120 Wang 80 79 78 79.00
130 Chen 70 69  68  69.00 
150 Wei 60 59 58 59.00

Now:
140  Ma 100 99 89 99.00
101 Li  90 89 88 89.00 
160 Hua 78 89 91 86.00 
120 Wang 80  79 78 79.00 
130 Chen 70. 69 68 69.00
150 Wei 60 59 58 59.00

题解

#include <stdio.h>
#include <stdlib.h>
struct student
  {char num[10];
   char name[8];
   int score[3];
   float ave;
   }st[10],s;

 int main()
  {FILE *fp,*fp1;
   int i,j,t,n;
   printf("\nNO.:");
   scanf("%s",s.num);
   printf("name:");
   scanf("%s",s.name);
   printf("score1,score2,score3:");
   scanf("%d,%d,%d",&s.score[0],&s.score[1],&s.score[2]);
   s.ave=(s.score[0]+s.score[1]+s.score[2])/3.0;

         //从文件读数据 
  if((fp=fopen("stu_sort","r"))==NULL)
    {printf("can not open file.");
     exit(0);
    }
  printf("original data:\n");
    for (i=0;fread(&st[i],sizeof(struct student),1,fp)!=0;i++)
      {printf("\n%8s%8s",st[i].num,st[i].name);
       for (j=0;j<3;j++)
	       printf("%8d",st[i].score[j]);
       printf("%10.2f",st[i].ave);
      }

  n=i;
  for (t=0;st[t].ave>s.ave && t<n;t++);

          //向文件写数据 
  printf("\nNow:\n");
  fp1=fopen("sort1.dat","w");
  for (i=0;i<t;i++)
    {fwrite(&st[i],sizeof(struct student),1,fp1);
     printf("\n %8s%8s",st[i].num,st[i].name);
     for (j=0;j<3;j++)
       printf("%8d",st[i].score[j]);
     printf("%10.2f",st[i].ave);
    }
  fwrite(&s,sizeof(struct student),1,fp1);
  printf("\n %8s %7s %7d %7d %7d%10.2f",s.num,s.name,s.score[0],s.score[1],s.score[2],s.ave);
  for (i=t;i<n;i++)
    {fwrite(&st[i],sizeof(struct student),1,fp1);
     printf("\n %8s%8s",st[i].num,st[i].name);
     for(j=0;j<3;j++)
       printf("%8d",st[i].score[j]);
     printf("%10.2f",st[i].ave);
     }
  printf("\n");
  fclose(fp);
  fclose(fp1);
  return 0;
 }


提示

数据范围、额外说明、样例说明等等