#include?
#include?
#include?

#define?STU?struct?Student
#define?LEN?sizeof（struct?Student）

void?back（）;

struct?Student{
	int?no;				//學號
	char?name[40];		//名字
	int?age;			//年齡
	char?sex;			//性別
	double?score[3];	//語數(shù)英三門成績
}*stu;

int?id?=?20191100;	//學號?自動生成
int?count?=?0;		//學生人數(shù)

void?save（）{		//保存文件
	FILE?*f?=?fopen（“file_stu.dat““w“）;
		if（f?!=?NULL）{
			fwrite（&countsizeof（count）1f）;
			fwrite（stuLEN*countcountf）;
			fclose（f）;
		}
}

void?load（）{		//加載文件
	FILE?*f?=?fopen（“file_stu.dat““r“）;
	if（f?!=?NULL）{		
		fread（&countsizeof（count）1f）;
		fread（stuLEN*countcountf）;
		fclose（f）;
	}
}

STU?*add（）{		//增加學生
	STU?*p;
	p?=?stu;
	p+=count;
	if（stu?==?NULL）{
		printf（“applied?failed!\n“）;
		back（）;
		return;
	}
	int?flag?=?1;
	while（flag）{
		p->no?=?id+count;
		printf（“please?input?student‘s?name:“）;
		scanf（“%s“p->name）;
		printf（“please?input?student‘s?age:“）;
		scanf（“%d“&p->age）;
		printf（“please?input?student‘s?sex:“）;
		scanf（“%*[^\n]“）;
		scanf（“%*c“）;
		scanf（“%c“&p->sex）;
		printf（“please?input?student‘s?score:“）;
		scanf（“%lf%lf%lf“&p->score[0]&p->score[1]&p->score[2]）;
		printf（“add?student?more?（1-YES0-NO）\n“）;
		scanf（“%d“&flag）;
		p++;
		count++;
	}
	back（）;
	return?stu;
}

STU?*delete（）{	//刪除學生
	if（stu?==?NULL）{
		printf（“the?list?is?empty!\n“）;
		back（）;
		return?stu;
	}
	STU?*p;
	p?=?stu;
	int?num;
	printf（“please?input?student?id?that?you?want?to?delete:“）;
	scanf（“%d“&num）;
	int?i?=?0;
	while（p[i].no?!=num?&&?i		i++;
	}
	if（num?==?p[i].no）{
		for（;i			p[i]?=?p[i+1];	
		}
		count--;
	}else{
		printf（“student?No:%d?is?not?exist!\n“num）;	
	}
	back（）;
	return?stu;
}

STU?*modif（）{	//修改學生信息
	if（stu?==?NULL）{
		printf（“the?list?is?empty!\n“）;
		back（）;
		return?stu;
	}
	printf（“please?input?student‘s?id?that?you?want?to?modify:“）;
	int?num;
	scanf（“%d“&num）;
	STU?*p;
	p?=?stu;
	int?i?=?0;
	while（p->no?!=?num?&&?i		i++;
		p++;
	}
	if（p->no?==?num）{
		printf（“student?No:%d?‘s?information?showed?as?below:\n“num）;
		printf（“ID:%d????name:%s????age:%d?????sex:%c\n“p->nop->namep->agep->sex）;
		printf（“chinese:%g??	math:%g?	english:%g\n“p->score[0]p->score[1]p->score[2]）;
		printf（“Please?select?the?items?you?want?to?change:\n“）;
		printf（“1~name??2~age??3~sex?4~chinese?score??5~math?score?6~english?score?0~done\n“）;
		while（1）{
			int?opt;
			scanf（“%d“&opt）;
			switch（opt）{
				case?1:
					printf（“input?new?name:“）;
					scanf（“%s“p->name）;
					break;
				case?2:
					printf（“input?new?age:“）;
					scanf（“%d“&p->age）;
					break;
				case?3:
					prin