void reduce()
{
	int i=0,j,k,id;
	FILE *fp1,*fp2,*ff;
	ff=fopen("b.txt","r");
	fscanf(ff,"%d",&j);
	close(ff);
		if((fp1=fopen("a.txt","r"))==NULL)
	{
		printf("file open error");
		exit(0);
	}
	printf("请输入要删除学生信息的学号\n");
	scanf("%d",&id);
	while(!feof(fp1))
	{
		fscanf(fp1,"%d%d%s%d%d%d%d",&student[i].id,&student[i].class,&student[i].name,&student[i].time_beginhour,&student[i].time_beginminute,&student[i].time_endhour,&student[i].time_endminute);
		i++;
		j=i;
	}
	fclose(fp1);
	for(i=0;i<=j;i++)
	{
		if(student[i].id==id)
		k=i;
	}
	fp2=fopen("a.txt","w");
	if(k==0)
	{
		for(i=1;i<=j;i++)
		fprintf(fp2,"%d%d%s%d%d%d%d",student[i].id,student[i].class,student[i].name,student[i].time_beginhour,student[i].time_beginminute,student[i].time_endhour,student[i].time_endminute);
	}
	if(k>0)
	{
	for(i=0;i<k;i++)
	fprintf(fp2,"%d%d%s%d%d%d%d",student[i].id,student[i].class,student[i].name,student[i].time_beginhour,student[i].time_beginminute,student[i].time_endhour,student[i].time_endminute);
	for(i=(k+1);i<=j;i++)
	fprintf(fp2,"%d%d%s%d%d%d%d",student[i].id,student[i].class,student[i].name,student[i].time_beginhour,student[i].time_beginminute,student[i].time_endhour,student[i].time_endminute);
    }
	fclose(fp2);
	ff=fopen("b.txt","w");
	fprintf(ff,"%d",j-1);
	fclose(ff);
	printf("删除成功");
}
void classfind()
{
	FILE *fp;
	int class,i=0,j;
		if((fp=fopen("a.txt","r"))==NULL)
	{
		printf("file open error");
		exit(0);
	}
	printf("请输入要查找的班级\n");
	scanf("%d",&class);
	while(!feof(fp))
	{
		fscanf(fp,"%d%d%s%d%d%d%d",&student[i].id,&student[i].class,&student[i].name,&student[i].time_beginhour,&student[i].time_beginminute,&student[i].time_endhour,&student[i].time_endminute);
		i++;
		j=i;
	}
	for(i=0;i<=j;i++)
	{
	if(student[i].class==class)
	{
	printf("学号；%d\n",student[i].id);
	printf("班级；%d\n",student[i].class);
	printf("姓名；%s\n",student[i].name);
	printf("开始上机时间；%d:%d\n",student[i].time_beginhour,student[i].time_beginminute);
	printf("结束上机时间；%d:%d\n",student[i].time_endhour,student[i].time_endminute);
    }
    }
	fclose(fp);
}
void idfind()
{
	int id,i=0,j;
	FILE *fp; 
		if((fp=fopen("a.txt","r"))==NULL)
	{
		printf("file open error");
		exit(0);
	}
	printf("请输入要查找的学号\n");
	scanf("%d",&id);
	while(!feof(fp))
	{
		fscanf(fp,"%d%d%s%d%d%d%d",&student[i].id,&student[i].class,&student[i].name,&student[i].time_beginhour,&student[i].time_beginminute,&student[i].time_endhour,&student[i].time_endminute);
		i++;
		j=i;
	}
	for(i=0;i<=j;i++)
	{
	if(student[i].id==id)
	{
	printf("学号；%d\n",student[i].id);
	printf("班级；%d\n",student[i].class);
	printf("姓名；%s\n",student[i].name);
	printf("开始上机时间；%d:%d\n",student[i].time_beginhour,student[i].time_beginminute);
	printf("结束上机时间；%d:%d",student[i].time_endhour,student[i].time_endminute);
    }
    }
	fclose(fp);
}
void namefind()
{
	FILE *fp;
	int i=0,j;
	char name[10];
		if((fp=fopen("a.txt","r"))==NULL)
	{
		printf("file open error");
		exit(0);
	}
	printf("请输入要查找的姓名\n");
	scanf("%s",&name);
	while(!feof(fp))
	{
		fscanf(fp,"%d%d%s%d%d%d%d",&student[i].id,&student[i].class,&student[i].name,&student[i].time_beginhour,&student[i].time_beginminute,&student[i].time_endhour,&student[i].time_endminute);
		i++;
		j=i;
	}
	for(i=0;i<=j;i++)
	{
	if(strcmp(student[i].name,name)==0)
	{
	printf("学号；%d\n",student[i].id);
	printf("班级；%d\n",student[i].class);
	printf("姓名；%s\n",student[i].name);
	printf("开始上机时间；%d:%d\n",student[i].time_beginhour,student[i].time_beginminute);
	printf("结束上机时间；%d:%d",student[i].time_endhour,student[i].time_endminute);
    }
    }
	fclose(fp);
}