四种方法实现学生信息管理系统（C语言）_学生管理信息系统c语言

语言：
C
平台：
VS2017
程序打包下载：
https://download.csdn.net/download/qq_41027556/15647720

学生信息管理系统

数组实现学生信息管理系统

功能：
学生信息的读取
姓名/学号/成绩的排序
学生姓名或学号进行查询
学生增删
数量固定
代码：

# include<stdio.h>
#include<string.h>
#include<math.h>
#include<stdlib.h>
#define maxsize 50
char names[50][maxsize]; 
//《苏-C程序设计》 P254 字符串数组
int num[maxsize];
int mandarin[maxsize];
int math[maxsize];
int english[maxsize];
int sum_score[maxsize];
int i, n,j,m;
//int sum[maxsize];
char temp_name[50][maxsize];
int temp_num[maxsize];
int temp_mandarin[maxsize];
int temp_math[maxsize];
int temp_eng[maxsize];
int temp_sum[maxsize];
int sequence[maxsize];

int students_show_menu();
void  students_input();
void students_show();
int students_numfind();
int student_namefind();
void num_seq();
void name_seq();
void students_add();
int students_del();

int main()
{
	int choose;
	while (1)
	{
		students_show_menu();
		printf("请输入您的选择：");
		scanf_s("%d", &choose);
		switch (choose)
		{
		case(1)://输入学生信息
			students_input();
			break;
		case(2)://输出全部信息
			students_show();
			break;
		case(3)://学号查找
			students_numfind();
			break;
		case(4)://姓名查找
			student_namefind();
			break;
		case(5)://学号排序
			num_seq();
			break;
		case(6)://姓名排序
			name_seq();
			break;
		case(7)://添加
			students_add();
			break;
		case(8)://删除
			students_del();
			break;
		case (0)://退出 
			printf("\n退出系统成功\n");
			printf("欢迎再次使用【学生信息管理系统v1.0】\n\n");
			exit(0);
			//正常退出（如果main()在一个递归程序中，exit()仍然会终止程序;但return将控制权移交给递归的前一级）
		default:
			printf("\n您输入的操作有误。请重新输入！\n");
			break;
		}
	}
}


int students_show_menu() 	//显示菜单
{
	printf("\n");
	for (int i = 1; i < 50; i++)
		printf("*");
	printf("\n");
	printf("欢迎使用学生信息管理系统v1.0\n\n");
	printf("1.输入全部学生信息\n");
	printf("2.读取全部学生信息\n");
	printf("3.按学号查询学生\n");
	printf("4.按姓名查询学生\n");
	printf("5.按学号排序学生\n");
	printf("6.按成绩排序学生\n");
	printf("7.添加学生信息\n");
	printf("8.删除学生信息\n");
	printf("0.退出系统\n\n");
	for (int i = 1; i < 50; i++)
		printf("*");
	printf("\n");
	return 0;
}

void  students_input() //输入所有学生信息
{
	printf("\n【1】输入全部学生信息\n");
	printf("输入学生个数：");
	scanf_s("%d", &n);
	for (i = 0; i < n; i++)
	{
		printf("\n请输入第%d个学生的信息：\n", i + 1);
		printf("请输入学生姓名：");
		scanf_s("%s", names[i],50);
		printf("请输入学生学号：");
		scanf_s("%d", &num[i]);
		printf("请输入学生语文成绩：");
		scanf_s("%d",&mandarin[i]);
		printf("请输入学生数学成绩：");
		scanf_s("%d", &math[i]);
		printf("请输入学生英语成绩：");
		scanf_s("%d", &english[i]);
		sum_score[i] = mandarin[i] + math[i] + english[i];
	}
	printf("\n添加学生信息成功！\n");
}

void students_show() //学生信息的读取
{
	printf("\n【2】读取全部学生信息\n");
	int len = strlen(*names);
	if (len == 0)
	{
		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
		return;
	}
	printf("\n姓名\t\t学号\t\t语文成绩\t数学成绩\t英语成绩\t总成绩\t\t\n");
	for ( i = 1; i < 100; i++)
		printf("-");
	printf("\n");
	for (j = 0; j< n+m; j++)
	{
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n", names[j], num[j], mandarin[j],
																						math[j],english[j], sum_score[j]);
	}
	for (i = 1; i < 100; i++)
		printf("-");
	printf("\n");
}

int students_numfind() //按学号查找
{
	printf("【3】按学号查询学生\n");
	int nums;
	int find_num = -1;
	printf("\n请输入待查找学生学号：");
	scanf_s("%d", &nums);
	for (i = 0; i < n+m; i++)
	{
		if (nums == num[i])
		{
			find_num = i;
			break;
		}
	}
	if (find_num == -1)
	{
		printf("\n抱歉，没有找到该学生的信息! \n");
		return 0;
	}
	else
	{
		printf("\n查找学生信息成功！\n");
		printf("\n姓名\t\t学号\t\t语文成绩\t数学成绩\t英语成绩\t总成绩\t\t\n");
		for (i = 1; i < 100; i++)
			printf("-");
		printf("\n%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n", names[find_num], num[find_num], mandarin[find_num],
			math[find_num], english[find_num], sum_score[find_num]);
		for (i = 1; i < 100; i++)
			printf("-");
		printf("\n");
	}
	return 1;
}

int student_namefind() //按姓名查找
{
	printf("【4】按姓名查询学生\n");
	char name_str[50];
	int find_name = -1;
	printf("\n请输入待查找学生姓名：");
	scanf_s("%s", name_str,50);  //此值应小于定义（50）
	//输入参数是已经定义好的“字符数组名”, 不用加&
	//在C语言中数组名就代表该数组的起始地址
	for (i = 0; i < n+m; i++)
	{
		if (strcmp(name_str, names[i]) == 0)
			/*strcmp函数是string compare(字符串比较)的缩写，用于比较两个字符串并根据比较结果返回整数。
			基本形式为strcmp(str1,str2)，若str1=str2，则返回零；若str1str2，则返回正数。*/
		{
			find_name = i;
			break;
		}
	}
	if (find_name == -1)
	{
		printf("\n抱歉，没有找到该学生的信息! \n");
		return 0;
	}
	else
	{
		printf("\n查找学生信息成功！\n");
		printf("\n姓名\t\t学号\t\t语文成绩\t数学成绩\t英语成绩\t总成绩\t\t\n");
		for (i = 1; i < 100; i++)
			printf("-");
		printf("\n%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n", names[find_name], num[find_name], mandarin[find_name],
			math[find_name], english[find_name], sum_score[find_name]);
		for (i = 1; i < 100; i++)
			printf("-");
		printf("\n");
	}
	return 1;
}

void num_seq() //按学号排序
{
	printf("\n【5】按学号排序学生\n");
	int max, min;
	for (i = 0; i < n+m; i++)
	{
		temp_num[i] = num[i];
	}
	max = 0;
	for (j = 1; j < n+m; j++)
	{
		if (temp_num[max] < temp_num[j])
		{
			max = j;
		}
	}
	sequence[n +m- 1] = max;
	for (i = 0; i < n+m-1; i++)
	{
		min = i;
		for (j = 0; j < n+m; j++)
		{
			if (temp_num[min] > temp_num[j])
			{
				min = j;
			}
		}
		sequence[i] = min;
		temp_num[min] = temp_num[max];
		//利用临时数组将查找过的学生信息的学号设为最大值，排除查找的干扰 
	}
	for (i = 0; i < n+m; i++)
	{
		//strcpy(temp_name[i], names[i]); //strcpy(a,b); 将b中的COPY复制到a中		
		strcpy_s(temp_name[i], 50 * sizeof(char),names[i]);/*若新建项目时不选选择安全开发生命周期(SDL)检查
																						运行上一句没有问题，同一语句在 Devc++ 中可以运行 */
		//*temp_name[i] = names[i];
		//memcpy(temp_name, names,sizeof(names) );
		temp_num[i] = num[i];
		temp_mandarin[i] = mandarin[i];
		temp_math[i] = math[i];
		temp_eng[i] = english[i];
		temp_sum[i] = sum_score[i];
	}
	for(i=0; i<n+m; i++)
	{
		//strcpy(names[i], temp_name[sequence[i]]);
		strcpy_s(names[i], 50 * sizeof(char),temp_name[sequence[i]]);
		//*names[i] = temp_name[sequence[i]];
		//memcpy(names, temp_name,sizeof(temp_name) );
		num[i] = temp_num[sequence[i]];
		mandarin[i] = temp_mandarin[sequence[i]];
		math[i] = temp_math[sequence[i]];
		english[i] = temp_eng[sequence[i]];
		sum_score[i] = temp_sum[sequence[i]];
	}
	printf("\n排序完毕，结果如下：\n");
	printf("\n姓名\t\t学号\t\t语文成绩\t数学成绩\t英语成绩\t总成绩\t\t\n");
	for (i = 1; i < 100; i++)
		printf("-");
	printf("\n");
	for (j = 0; j< n+m; j++)
	{
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n", names[j], num[j], mandarin[j],
			math[j], english[j], sum_score[j]);
	}
	for (i = 1; i < 100; i++)
		printf("-");
	printf("\n");
	return;
}

void name_seq() //按成绩排序
{
	printf("\n【6】按成绩排序学生\n");
	int max,min;
	for (i = 0; i < n+m ; i++)
	{
		temp_sum[i] = sum_score[i];
	}
	max = 0;
	for (j = 0; j < n+m; j++)
	{
		if (temp_sum[max] < temp_sum[j])
			max = j;
	}
	sequence[n+m - 1] = max;
	for (i = 0; i < n+m - 1; i++)
	{
		min = i;
		for (j = 0; j < n+m; j++)
		{
			if (temp_sum[min] > temp_sum[j])
				min = j;
		}
		sequence[i] = min;
		temp_sum[min] = temp_sum[max];
	}
	for (i = 0; i < n+m; i++)
	{
		strcpy_s(temp_name[i], 50 * sizeof(char), names[i]);
		temp_num[i] = num[i];
		temp_mandarin[i] = mandarin[i];
		temp_math[i] = math[i];
		temp_eng[i] = english[i];
		temp_sum[i] = sum_score[i];
	}
	for (i = 0; i < n+m; i++)
	{
		strcpy_s(names[i], 50 * sizeof(char), temp_name[sequence[i]]);
		num[i] = temp_num[sequence[i]];
		mandarin[i] = temp_mandarin[sequence[i]];
		math[i] = temp_math[sequence[i]];
		english[i] = temp_eng[sequence[i]];
		sum_score[i] = temp_sum[sequence[i]];
	}
	printf("\n排序完毕，结果如下：\n");
	printf("\n姓名\t\t学号\t\t语文成绩\t数学成绩\t英语成绩\t总成绩\t\t\n");
	for (i = 1; i < 100; i++)
		printf("-");
	printf("\n");
	for (j = 0; j< n+m; j++)
	{
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n", names[j], num[j], mandarin[j],
			math[j], english[j], sum_score[j]);
	}
	for (i = 1; i < 100; i++)
		printf("-");
	printf("\n");
	return;
}

void students_add() //新增学生信息
{
	printf("\n【7】添加学生信息\n");
	printf("输入增加学生个数：");
	scanf_s("%d", &m);
	for (i = n; i < n+m; i++)
	{
		printf("\n请输入第%d个(除去已有学生，则为第%d个)学生的信息：\n", i + 1 , i-n+1);
		printf("请输入学生姓名：");
		scanf_s("%s", names[i], 50);
		printf("请输入学生学号：");
		scanf_s("%d", &num[i]);
		printf("请输入学生语文成绩：");
		scanf_s("%d", &mandarin[i]);
		printf("请输入学生数学成绩：");
		scanf_s("%d", &math[i]);
		printf("请输入学生英语成绩：");
		scanf_s("%d", &english[i]);
		sum_score[i] = mandarin[i] + math[i] + english[i];
	}
	printf("\n添加学生信息成功！\n");
}

int students_del() //删除学生信息
{
	printf("\n【8】删除学生信息\n");
	char name_f[maxsize];
	int findstu=-1;
	printf("请输入需要删除的学生信息：");
	scanf_s("%s", name_f,50);
	for (i = 0; i < n + m; i++)
	{
		if (strcmp(name_f, names[i]) == 0)
		{
			findstu = i;
			break;
		}
	}
	if (findstu == -1)
	{
		printf("\n没有该学生的信息! \n");
		return 0;
	}
	else
	{
		for (i = findstu; i < n + m - 1; i++)
		{
			strcpy_s(names[i], 50 * sizeof(char), names[i + 1]);
			num[i] = num[i + 1];
			mandarin[i] = mandarin[i + 1];
			math[i] = math[i + 1];
			english[i] = english[i + 1];
			sum_score[i] = sum_score[i + 1];
		}
		n--;
	}
	printf("删除成功！\n");
	return 1;
}

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单链表实现学生信息管理系统

功能：
同上
信息读取
排序
查询
无限增删
代码：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define maxsize 50

typedef struct
{
	char names[maxsize];
	int num;
	int math;
	int english;
	int sum_score;
}student;
student f;
student f2;
student in;
student dl;
typedef struct LNode
{
	student data;
	struct LNode *next;
}LNode;


int i, j, n, m;

int student_show_menu();
void student_show(LNode *head); //读取全部学生信息
void student_input(LNode *head); //输入学生信息
int name_find(LNode *head, student f); //按姓名查询学生
int num_find(LNode *head, student f2); //按学号查找学生
void num_seq(LNode *head); //按学号排序
void sum_seq(LNode *head); //按总成绩排序
void stu_insert(LNode *head, student in); //增加学生信息
void stu_del(LNode *head, student *dl); //删除学生信息

int main()
{
	LNode *head = (LNode*)malloc(sizeof(LNode));
	head->next = NULL;
	int choose;

	while (1)
	{
		student_show_menu();
		printf("请输入您的选择：");
		scanf_s("%d", &choose);
		switch (choose)
		{
		case(1):
			student_input(head);//输入信息
			break;
		case(2):
			student_show(head); //显示信息
			break;
		case(3):
			name_find(head, f); //按姓名查找
			break;
		case(4):
			num_find(head, f2); //按学号查找
			break;
		case(5):
			num_seq(head);	//按学号排序
			break;
		case(6):
			sum_seq(head); //按总成绩排序
 			break;
		case(7):
			stu_insert(head,in); //增加学生
			break;
		case(8):
			stu_del(head, &dl); //删除学生  (对比*、&)  声明函数的时候指针用*代表指针类型，&获取目标地址传递给指针
												//在声明中使用*代表取目标地址存储的值。*是指针引用，&是地址引用
			break;
		case (0)://退出系统
			printf("\n退出系统成功\n");
			printf("欢迎再次使用【学生信息管理系统v2.0】\n\n");
			exit(0);
		default:
			printf("\n您输入的操作有误。请重新输入！\n");
			break;
		}
	}
	return 0;
}


int student_show_menu() //显示菜单
{
	printf("\n");
	for (int i = 1; i < 50; i++)
		printf("*");
	printf("\n");
	printf("欢迎使用学生信息管理系统v2.0\n\n");
	printf("1.输入全部学生信息\n");
	printf("2.读取全部学生信息\n");
	printf("3.按姓名查询学生\n");
	printf("4.按学号查询学生\n");
	printf("5.按学号排序学生\n");
	printf("6.按总成绩排序学生\n");
	printf("7.添加学生信息\n");
	printf("8.删除学生信息\n");
	printf("0.退出系统\n\n");
	for (int i = 1; i < 50; i++)
		printf("*");
	printf("\n");
	return 0;
}

void student_input(LNode *head) //输入学生信息
{
	printf("\n【1】输入全部学生信息\n");
	printf("输入学生个数：");
	scanf_s("%d", &n);
	LNode *p;
	LNode *r = head;
	printf("请输入学生信息：\n");
	for (i = 0; i < n; i++)
	{
		p = (LNode*)malloc(sizeof(LNode));
		p->next = NULL;
		printf("请输入学生姓名：");
		scanf_s("%s", p->data.names, maxsize);
		printf("请输入学号：");
		scanf_s("%d", &p->data.num);
		printf("请输入学生数学成绩：");
		scanf_s("%d", &p->data.math);
		printf("请输入学生英语成绩：");
		scanf_s("%d", &p->data.english);
		//int *sum = p->data.sum_score;
		p->data.sum_score = p->data.math + p->data.english;
		r->next = p;
		r = r->next;
		//free(p);		//若使用了此句，后续输出列表会出错。因为每个空间的数据都是有用的，所以不用free。
		printf("\n");
	}
	printf("\n添加学生信息成功！\n");
	//return head;
}

void student_show(LNode *head) //读取全部学生信息
{
	printf("\n【2】读取全部学生信息\n");
	LNode *p;
	p = head;
	if (p->next == NULL)
	{
		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
		return;
	}
	printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
	while (p->next != NULL)
	{
		p = p->next;
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n", 
			p->data.names, p->data.num,p->data.math, p->data.english, p->data.sum_score);
	}
}

int name_find(LNode *head,student f) //按姓名查询学生
{
	printf("【3】按姓名查询学生\n");
	LNode *p;
	p = head;
	printf("请输入查找学生姓名：");
	scanf_s("%s", f.names,maxsize);
	while ((p->next != NULL)&&strcmp(f.names,p->data.names)) //str1=str2，则返回零；若str1!=str2，则返回正数
	{
		p = p->next;
	}
	if ((p->next == NULL)&& strcmp(f.names, p->data.names))
	{
		printf("\n抱歉，没有找到该学生的信息! \n");
		return 0;
	}
	else
	{
		printf("\n查找学生信息成功！\n");
		printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n", 
			p->data.names, p->data.num, p->data.math, p->data.english, p->data.sum_score);
		return 1;
	}
}

int num_find(LNode *head, student f2) //按学号查找学生
{
	printf("【4】按学号查询学生\n");
	LNode *p;
	p = head;
	printf("请输入查找学生学号：");
	scanf_s("%d", &f2.num);
	while ((p->next != NULL) && (p->data.num != f2.num)) 
	{
		p = p->next;
	}
	if ((p->next == NULL) && (p->data.num != f2.num))
	{
		printf("\n抱歉，没有找到该学生的信息! \n");
		return 0;
	}
	else
	{
		printf("\n查找学生信息成功！\n");
		printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
			p->data.names, p->data.num, p->data.math, p->data.english, p->data.sum_score);
		return 1;
	}
}

void num_seq(LNode *head) //按学号排序
{
	printf("\n【5】按学号排序学生\n");
	LNode *newhead, *rear;
	newhead = head->next;
	rear = NULL;
	if (newhead == NULL || newhead->next == NULL)
	{
		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
		return;
	}
	while (newhead!=rear)
	{
		while (newhead->next!=rear)
		{
			if (newhead->data.num > newhead->next->data.num)
			{
				int temp = newhead->data.num;
				newhead->data.num = newhead->next->data.num;
				newhead->next->data.num = temp;
				int temp1 = newhead->data.math;
				newhead->data.math = newhead->next->data.math;
				newhead->next->data.math = temp1;
				int temp2 = newhead->data.english;
				newhead->data.english = newhead->next->data.english;
				newhead->next->data.english = temp2;
				int temp3 = newhead->data.sum_score;
				newhead->data.sum_score = newhead->next->data.sum_score;
				newhead->next->data.sum_score = temp3;
				//char temp4_str = gets(newhead->data.names, sizeof(char));
				//char *temp4 = newhead->data.names; //先替换了此值，故第二个strcpy使用*temp4已经是新值了。
				student str;
				strcpy_s(str.names, maxsize, newhead->data.names);
				//gets_s(newhead->data.names,maxsize);
				//newhead->data.names = newhead->next->data.names;
				strcpy_s(newhead->data.names,  maxsize, newhead->next->data.names);
				//newhead->next->data.names = temp4;
				strcpy_s(newhead->next->data.names, maxsize, str.names);
			}
			newhead = newhead->next;
		}
		rear = newhead;
		newhead = head->next;
	}
	printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
	while (head->next != NULL)
	{
		head = head->next;
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
			head->data.names, head->data.num, head->data.math, head->data.english, head->data.sum_score);
	}
}

void sum_seq(LNode *head) //按总成绩排序
{
	printf("\n【6】按总成绩排序学生\n");
	LNode *newhead, *rear;
	newhead = head->next;
	rear = NULL;
	if (newhead == NULL || newhead->next == NULL)
	{
		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
		return;
	}
	while (newhead != rear)
	{
		while (newhead->next != rear)
		{
			if (newhead->data.sum_score < newhead->next->data.sum_score)
			{
				int temp = newhead->data.num;
				newhead->data.num = newhead->next->data.num;
				newhead->next->data.num = temp;
				int temp1 = newhead->data.math;
				newhead->data.math = newhead->next->data.math;
				newhead->next->data.math = temp1;
				int temp2 = newhead->data.english;
				newhead->data.english = newhead->next->data.english;
				newhead->next->data.english = temp2;
				int temp3 = newhead->data.sum_score;
				newhead->data.sum_score = newhead->next->data.sum_score;
				newhead->next->data.sum_score = temp3;
				student str;
				strcpy_s(str.names, strlen(newhead->data.names)+1 , newhead->data.names);
				strcpy_s(newhead->data.names, strlen(newhead->next->data.names) + 1, newhead->next->data.names); //注意缓冲区长度，strlen()函数计算的字符串长度是不包括'\0’
				strcpy_s(newhead->next->data.names, strlen(str.names) + 1, str.names);
			}
			newhead = newhead->next;
		}
		rear = newhead;
		newhead = head->next;
	}
	printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
	while (head->next != NULL)
	{
		head = head->next;
		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
			head->data.names, head->data.num, head->data.math, head->data.english, head->data.sum_score);
	}
}

void stu_insert(LNode *head,student in) //增加学生信息
{
	printf("\n【7】添加学生信息\n");
	printf("请输入学生信息：\n");
	printf("请输入学生姓名：");
	scanf_s("%s", in.names, maxsize);
	printf("请输入学号：");
	scanf_s("%d", &in.num);
	printf("请输入学生数学成绩：");
	scanf_s("%d", &in.math);
	printf("请输入学生英语成绩：");
	scanf_s("%d", &in.english);
	in.sum_score  = in.math + in.english ;
	LNode *stu, *r;
	r = head;
	int d,dp=0;
	printf("请输入要插入的位置：");
	scanf_s("%d", &d);
	while ((r != NULL) && (dp < d-1))
	{
		r = r->next;
		dp = dp + 1;
	}
	if (r == NULL)
	{
		printf("\n插入错误，请重新输入。\n");
		return;
	}
	stu = (LNode*)malloc(sizeof(LNode));
	stu->data = in;
	stu->next = r->next;
	r->next = stu;
	printf("\n插入信息成功！\n");
}

void stu_del(LNode *head, student *dl) //删除学生信息
{
	printf("\n【8】删除学生信息\n");
	LNode *stu, *r;
	r = head;
	int d, dp = 0;
	printf("请输入要删除的位置：");
	scanf_s("%d", &d);
	while ((r->next != NULL) && (dp < d-1 ))
	{
		r = r->next;
		dp++;
	}
	if (r ->next== NULL)
	{
		printf("\n删除错误，请重新输入。\n");
		return;
	}
	stu = r->next;
	r->next = stu->next;
	*dl = stu->data; //此时应为*dl ,下面printf才能顺利输出
	free(stu);
	printf("删除%s成功!\n",dl->names);
	//return;
}
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嵌套链表实现学生信息管理系统

功能：
同上
信息读取
排序
查询
无限增删
学生增删
将个人学习与科目成绩分为两单链表

代码：

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define maxsize 20

//成绩链表
typedef struct LNode1
{
	char subject[maxsize];
	int chengji;
	struct LNode1 *next;
}O;
//学生链表
typedef struct LNode2
{
	int num;
	char name[maxsize];
	int count;//成绩数目
	O* p;
	O* head1; //成绩头结点
	struct LNode2 *next;
}S;
int count = 0;

S* addstudent(S *head2); //插入学生
void addscore(S *p); //插入成绩（头）
void insertscore(O *head1, char str[], int sco); //插入成绩
void stuprint(S *head2); //输出学生
void scoreprint(O* head1); //输出成绩
void addso(S* head2); //给某人增加成绩
void show(S* head2, int cas, char str[], int xuehao); //查找
void search(S* head2); //操作【4】
int searchscore(O* head1, char str[], S* a); //判断科目
void sortbynum(S* head2); //按学号排序
void sortbysub(S* head2); //按科目排序
int stusort(S* head2);//按个人成绩
O* mergeSort(O* head1);//接上排序
S* delstu(S* head2);//删除学生

int main()
{
	S *head2 = (S*)malloc(sizeof(S));	//学生根结点
	head2->head1 = (O*)malloc(sizeof(O)); //※这里不写清楚，search中无法读取head2->head1(在都是头结点的情况！)
	head2->next = NULL;
	head2->head1->next = NULL;
	int choose;
	printf("\n");
	while (1)
	{
		printf("\n");
		for (int i = 0; i < 50; i++)
			printf("*");
		printf("\n");
		printf("欢迎使用学生信息管理系统V3.0\n\n");
		printf("【1】. 添加学生\n");
		printf("【2】. 输出学生信息\n");
		printf("【3】. 添加单个人成绩\n");
		printf("【4】. 查找学生\n");
		printf("【5】. 按学号排序\n");
		printf("【6】. 按科目成绩排序\n");
		printf("【7】. 学生个人成绩排序\n");
		printf("【8】. 删除学生\n");
		printf("【0】. 退出系统\n\n");
		for (int i = 1; i < 50; i++)
			printf("*");
		printf("\n");
		printf("请输入您的选择:");
		scanf("%d", &choose);
		switch (choose)
		{
		case 1:
			head2 = addstudent(head2); //添加学生
			break; 
		case 2:
			stuprint(head2); //输出学生信息
			break;
		case 3:
			addso(head2); //给单人添加成绩
			break;
		case 4:
			search(head2); // 查找学生
			break;
		case 5:			
			sortbynum(head2); //按学号排序
			break;
		case 6:
			sortbysub(head2);//按科目排序
			break;
		case 7:
			stusort(head2); //按个人成绩排序
			break;
		case 8:
			delstu(head2);//删除学生
			break;
		case 0:
			printf("\n退出系统成功\n");
			printf("欢迎再次使用【学生信息管理系统v3.0】\n\n");
			exit(0);
		default:
			printf("\n您输入的操作有误。请重新输入！\n");
			break;
		}
	}
}

S* addstudent(S *head2)  //添加学生
{
	int cse, no;
	char str[maxsize];
	while (1)
	{
		for (int i = 1; i < 50; i++)
			printf("-");
		printf("\n");
		printf("输入学生学号:");
		scanf("%d", &no);
		printf("输入学生姓名:");
		scanf("%s", str);
		S *p = (S*)malloc(sizeof(S));
		strcpy(p->name, str);
		p->num=no;
		p->next = head2->next;
		head2->next = p;
		p->count = 0;
		printf("是否为学生添加成绩(1.是  2.否):");
		scanf("%d", &cse);
		if (cse == 1)
		{
			addscore(p);
		}
		printf("添加学生信息成功!");
		printf("是否继续添加学生(1.是  2.否):");
		scanf("%d", &cse);
		if (cse != 1)
		{
			break;
		}
	}
	return head2;
}


void addscore(S *p) //添加成绩
{
	int cas, sco;
	char str[maxsize];
	while (1)
	{
		printf("输入科目:");
		scanf("%s", str);
		printf("输入成绩:");
		scanf("%d", &sco);
		if (p->count == 0)
		{
			p->head1 = (O*)malloc(sizeof(O));
			p->head1->next = NULL;
			O *p1 = (O *)malloc(sizeof(O));
			strcpy(p1->subject, str);
			p1->chengji=sco;
			p1->next = p->head1->next;
			p->head1->next = p1;
			p->count++;
		}
		else
		{
			insertscore(p->head1, str, sco);
			p->count++;
		}
		printf("添加成绩成功!是否继续添加成绩(1.是  2.否):");
		scanf("%d", &cas);
		if (cas != 1)
		{
			break;
		}
	}
}

void insertscore(O *head1, char str[], int sco) //成绩链表元素插入
{
	//int cas;
	if (head1 == NULL)
	{
		printf("新建错误。\n");
	}
	O *p1 = (O *)malloc(sizeof(O));
	strcpy(p1->subject, str);
	p1->chengji= sco;
	p1->next = head1->next;
	head1->next = p1;
}

void stuprint(S *head2) //输出学生信息
{
	S *q;
	q = head2;
	if (q->next == NULL)
	{
		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
		return;
	}
	printf("\n学号\t\t姓名\t\t\t\t\t成绩\n");
	while (q->next != NULL)
	{
		q = q->next;
		printf("%d\t\t%s\t\t\t",q->num,q->name);		
		scoreprint(q->head1);
	}
}

void scoreprint(O* head1) //输出成绩信息
{
	O *q1 = head1->next;
	if (q1 == NULL)
		return;
	while (q1 != NULL)
	{
		printf("\t%s:%d", q1->subject, q1->chengji);
		q1 = q1->next;
	}
	printf("\n");
}

void addso(S* head2) //给单个人增加成绩
{
	int xuehao = -1;
	char str[maxsize];
	printf("请输入学生姓名：");
	scanf("%s", str);
	show(head2, 5, str, xuehao);
}


void show(S* head2, int cas, char str[],int xuehao)  //查找显示学生信息
{
	if (head2 == NULL)
	{
		return;
	}
	if (cas == 5 && strcmp(head2->name, str) == 0 )
		addscore(head2);
	if (cas == 1 && (head2->num==xuehao) ) //按学号查找
	{
		printf("\n学号\t\t姓名\t\t\t\t\t成绩\n");
		printf("%d\t\t%s\t\t\t", head2->num, head2->name);
		scoreprint(head2->head1);
	}
	if (cas == 2 && strcmp(head2->name, str) == 0) //按姓名查找
	{
		printf("\n学号\t\t姓名\t\t\t\t\t成绩\n");
		printf("%d\t\t%s\t\t\t", head2->num, head2->name);
		scoreprint(head2->head1);
	}
	if (cas == 3 )
	{
		//if (head2 == NULL)	{head2 = head2->next;}
		if (searchscore(head2->head1, str, head2)) //该学生有本科目的成绩 
		{
			printf("学号:%d\t\t姓名:%s\t\t科目:%s\t\t成绩:%d", head2->num, head2->name,head2->p->subject,head2->p->chengji);
			printf("\n");
		}
	}
	show(head2->next, cas, str,xuehao);
}

void search(S* head2) //操作【4】
{
	int cas,xuehao=-1;
	//int no;
	char str[maxsize];
	//S* p;
	for (int i = 1; i < 50; i++)
		printf("+");
	printf("\n");
	printf("[1].按学号查找\n");
	printf("[2].按姓名查找\n");
	printf("[3].按科目查找\n");
	for (int i = 1; i < 50; i++)
		printf("+");
	printf("\n");
	printf("请输入操作：");
	scanf("%d", &cas);
	if (cas == 1)
	{
		printf("请输入学生学号：");
		scanf("%d", &xuehao);
	}
	if (cas == 2)
	{
		printf("请输入学生姓名：");
		scanf("%s", str);
	}
	if (cas == 3)
	{
		printf("请输入学生科目：");
		scanf("%s", str);
	}
	show(head2, cas, str,xuehao);
}


int searchscore(O* head1, char str[],S* p) //查找科目是否存在
{
	if (head1 == NULL)
		return 0;
	else if (strcmp(head1->subject, str) == 0)
	{
		p->p = head1;
		return 1;
	}
	else
		return searchscore(head1->next, str, p) ;
}

void sortbynum(S* head2) //按学号排序
{
	int len=0;
	S* ptr = head2->next;
	while (ptr != NULL)
	{
		len++;
		ptr = ptr->next;
	}
	S* shead, *p, *q, *tmp;
	int i, j;
	for (i = 0; i < len - 1; i++)
	{
		shead = head2;
		p = head2->next;
		q = p->next;
		for (j = 0; j < len - 1 - i; j++)
		{
			if (p->num > q->num)
			{
				shead->next = p->next;
				p->next = q->next;
				q->next = p;
				tmp = p;
				p = q;
				q = tmp;
			}
			shead = shead->next;
			p = p->next;
			q = q->next;
		}
	}
	stuprint(head2);
}

void sortbysub(S* head2) //按科目排序
{
	char str6[maxsize];
	S* newhead = (S*)malloc(sizeof(S));
	newhead->head1 = (O*)malloc(sizeof(O));
	newhead->next = NULL;
	newhead->head1->next = NULL;
	S* p6 = head2;
	S* p6_2 = p6->next;
	S *q6;
	q6 = newhead;
	printf("请输入学生科目：");
	scanf("%s", str6);
	while (p6 != NULL)
	{
		if (searchscore(p6->head1, str6, p6)) //该学生有本科目的成绩 
		{
			S* q6_2 = (S*)malloc(sizeof(S));
			q6_2->num = p6->num; strcpy(q6_2->name, p6->name); q6_2->head1 = p6->head1; q6_2->p = p6->p; q6_2->next = NULL;
			q6->next = q6_2;
			q6 = q6->next;
		}
		p6 = p6->next;
	}
	S *nq;
	nq = newhead;
	if (nq->next == NULL)
	{
		printf("\n当前没有任何学生信息记录! \n");
		return;
	}
	printf("\n有此科目者：");
	printf("\n学号\t\t姓名\t\t\t科目\t\t成绩\n");
	while (nq->next != NULL)
	{
		nq = nq->next;
		printf("%d\t\t%s\t\t\t%s\t\t%d\n", nq->num, nq->name,nq->p->subject,nq->p->chengji);
	}
	int len = 0;
	S* ptrk = newhead->next;
	while (ptrk != NULL)
	{
		len++;
		ptrk = ptrk->next;
	}
	S* sheadk, *pk, *qk, *tmpk;
	int i, j;
	for (i = 0; i < len - 1; i++)
	{
		sheadk = newhead;
		pk = newhead->next;
		qk = pk->next;
		for (j = 0; j < len - 1 - i; j++)
		{
			if (pk->p->chengji < qk->p->chengji)
			{
				sheadk->next = pk->next;
				pk->next = qk->next;
				qk->next = pk;
				tmpk = pk;
				pk = qk;
				qk = tmpk;
			}
			sheadk = sheadk->next;
			pk = pk->next;
			qk = qk->next;
		}
	}
	S *nqq = newhead;
	if (nqq->next == NULL)
	{
		printf("\n当前没有任何学生信息记录! \n");
		return;
	}
	printf("\n按科目成绩排序结果如下：");
	printf("\n学号\t\t姓名\t\t\t科目\t\t成绩\n");
	while (nqq->next != NULL)
	{
		nqq = nqq->next;
		printf("%d\t\t%s\t\t\t%s\t\t%d\n", nqq->num, nqq->name, nqq->p->subject, nqq->p->chengji);
	}
}

int stusort(S* head2) //学生个人成绩排序(小-->大)
{
	char str7[maxsize];
	printf("请输入学生姓名：");
	scanf("%s", str7);
	S *p7 = head2;
	while ((p7->next != NULL) && strcmp(str7, p7->name))
	{
		p7 = p7->next;
	}
	if ((p7->next == NULL) && strcmp(str7, p7->name))
	{
		printf("\n查无此人! \n");
		return 0;
	}
	else
	{
		O* p07 = mergeSort(p7->head1);
		O* p07_n = p07->next;
		printf("结果如下：");
		printf("\n学号\t\t姓名\t\t\t\t\t成绩\n");
		printf("%d\t\t%s\t\t\t", p7->num, p7->name);
		while (p07_n != NULL)
		{
			printf("\t%s:%d", p07_n->subject, p07_n->chengji);
			p07_n = p07_n->next;
		}
		printf("\n");
		return 1;
	}
}

O* mergeSort(O* head1) //归并
{
	if (head1 != NULL && head1->next != NULL)
	{
		O *fast = head1->next;
		O *slow = head1;
		while (fast != NULL && fast->next != NULL)
		{
			fast = fast->next->next;
			slow = slow->next; 
		}
		O *p1 = mergeSort(slow->next);
		slow->next = NULL;
		O *p2 = mergeSort(head1);
		O *p0 = (O*)malloc(sizeof(O));
		O *p = p0;
		while (p1 != NULL && p2 != NULL)
		{
			if (p1->chengji < p2->chengji)
			{
				p->next = p1;
				p1 = p1->next;
			}
			else
			{
				p->next = p2;
				p2 = p2->next;
			}
			p = p->next;
		}
		if (p1 != NULL)
		{
			p->next = p1;
		}
		if (p2 != NULL)
		{
			p->next = p2;
		}
		p = p0->next;
		free(p0);
		return p; //此时p对应head1，ASCII码中\0为0。
	}
	return head1;
}

S* delstu(S* head2)
{
	char str8[maxsize];
	printf("请输入学生姓名：");
	scanf("%s", str8);
	S *p8 = head2;
	while ((p8->next != NULL) && strcmp(str8, p8->name))
	{
		p8 = p8->next;
	}
	if ((p8->next == NULL) && strcmp(str8, p8->name))
	{
		printf("\n查无此人! \n");
		return 0;
	}
	else
	{
		S **pp8 = &head2;
		for (; *pp8; pp8 = &((*pp8)->next))
		{
			if (strcmp(str8, ((*pp8)->name)) == 0)
			{
				*pp8 = (*pp8)->next;
				break;
			}
		}
		printf("删除成功！\n");
		/*
		这种二级指针删除的方法参考自据说Linux大神的
		http://wordaligned.org/articles/two-star-programming
https://leetcode-cn.com/problems/shan-chu-lian-biao-de-jie-dian-lcof/solution/linusda-lao-de-jie-jue-fang-an-by-adjwang/
		*/
		return head2;	
	}
}

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二叉树实现学生信息管理系统

功能：
信息读取
排序
查询
无限增删
信息存储采用二叉树形式

代码：

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define maxsize 20

//成绩二叉树
typedef struct score
{
	char subject[maxsize];
	int chengji;
	struct score* left;
	struct score* right;
}O;

//学生二叉树
typedef struct student
{
	char num[maxsize];
	char name[maxsize];
	int count; //成绩数目
	O* p;
	O* head; //成绩头结点
	struct student* left;
	struct student* right;
}S;
int count = 0;

S*  addstudent(S *root); //增加学生
void addscore(S *root); //增加成绩
void insertscore(O *head, char str[], int sco); //成绩树插入
void insertstu(S *root, char str[], char no[]); //学生树插入
void scoreprint(O *head); //输出成绩信息
void stuprint(S* root);  //输出学生信息
void addso(S* root);//给个人加成绩
void show(S *root, int cas, char str[]); //查找学生信息，汇集一些遍历的操作（姓名/学号查找之类的）
void search(S* root); //查找函数
void stusort(S* root); //按个人成绩排序
void sortbyname(S* root); //按姓名排序 ※
void sortbysub(S* root); //按科目排序
void allshow(S* root); //显示所有学生信息

int main()
{
	S *root = NULL; //学生根节点 
	int choose;
	printf("\n");
	while (1) {
		for (int i = 1; i < 50; i++)
			printf("*");
		printf("\n");
		printf("欢迎使用学生信息管理系统v3.0\n\n");
		printf("【1】. 添加学生\n");
		printf("【2】. 添加成绩\n");
		printf("【3】. 查找学生\n");
		printf("【4】. 按学号排序\n");
		printf("【5】. 按姓名排序\n");
		printf("【6】. 按单科成绩排序\n");
		printf("【7】. 学生个人成绩排序\n");
		printf("【0】. 退出系统\n\n");
		for (int i = 1; i < 50; i++)
			printf("*");
		printf("\n");
		printf("请输入您的选择:");
		scanf("%d", &choose);
		switch (choose) 
		{
		case 1:
			root = addstudent(root);
			break;	 //添加学生
		case 2:
			addso(root);
			break;  //添加个人成绩
		case 3:
			search(root);
			break;		//查找(学号、姓名、科目)
		case 4:
			allshow(root);
			break; //按学号排序(输出全部信息)
		case 5:
			sortbyname(root);
			break; //按姓名排序
		case 6:
			sortbysub(root);
			break; //按科目排序
		case 7:
			stusort(root);
			break; //个人的成绩排序
		case 0:  //退出系统
			printf("\n退出系统成功\n");
			printf("欢迎再次使用【学生信息管理系统v3.0】\n\n");
			exit(0);
		default:
			printf("\n您输入的操作有误。请重新输入！\n");
			break;
		}
	}
}

//增加学生
S*  addstudent(S *root) 
{
	int cse;
	char str[maxsize], no[maxsize];
	while (1)
	{
		for (int i = 1; i < 50; i++)
			printf("-");
		printf("\n");
		printf("输入学生学号:");
		scanf("%s", no);
		printf("输入学生姓名:");
		scanf("%s", str);
		if (count == 0)
		{
			root = (S*)malloc(sizeof(S*));
			strcpy(root->name, str);
			strcpy(root->num, no);
			root->left = NULL;
			root->right = NULL;
			root->head = NULL;
			root->count = 0;
			printf("是否为学生添加成绩(1.是  2.否):");
			scanf("%d", &cse);
			if (cse == 1)
			{
				addscore(root);
			}
			count++;
		}
		else
		{
			insertstu(root, str, no);
		}
		printf("添加学生信息成功!");
		printf("是否继续添加学生(1.是  2.否):");
		scanf("%d", &cse);
		if (cse != 1)
		{
			break;
		}
	}
	return root;
}

//新增成绩
void addscore(S *root) 
{
	int sco, cas;
	char str[20];
	while (1) 
	{
		printf("输入科目:");
		scanf("%s", str);
		printf("输入成绩:");
		scanf("%d", &sco);
		if (root->count == 0) 
		{
			root->head = (O *)malloc(sizeof(O));	//根节点创建
			strcpy(root->head->subject, str);
			root->head->chengji = sco;
			root->head->left = NULL;
			root->head->right = NULL;
			root->count++;
		}
		else 
		{
			insertscore(root->head, str, sco);
		}
		printf("添加成绩成功!是否继续添加成绩(1.是  2.否):");
		scanf("%d", &cas);
		if (cas != 1) 
		{
			break;
		}
	}
}
 
//成绩树插入
void insertscore(O *head, char str[], int sco) 
{
	int cas;
	if (head == NULL) 
	{
		printf("新建错误。\n");
	}
	else if (sco >= head->chengji) 
	{
		if (head->left == NULL) 
		{
			O *p = (O *)malloc(sizeof(O));	 //根节点创建
			strcpy(p->subject, str);
			p->chengji = sco;
			p->left = NULL;
			p->right = NULL;
			head->left = p;
		}
		else 
		{
			insertscore(head->left, str, sco);
		}
	}
	else 
	{
		if (head->right == NULL) {
			O *p = (O *)malloc(sizeof(O));	 //根节点创建
			strcpy(p->subject, str);
			p->chengji = sco;
			p->left = NULL;
			p->right = NULL;
			head->right = p;
		}
		else 
		{
			insertscore(head->right, str, sco);
		}
	}
}

//学生树插入
void insertstu(S *root, char str[], char no[]) 
{
	int cas;
	//strcmp(str1, str2)，若str1 = str2，则返回零；若str1<str2，则返回负数；若str1>str2，则返回正数。
	if (strcmp(root->num, no) > 0)
	{
		if (root->left == NULL)
		{
			S *p = (S *)malloc(sizeof(S));	//节点创建
			strcpy(p->name, str);
			strcpy(p->num, no);
			p->left = NULL;
			p->right = NULL;
			p->head = NULL;
			p->count = 0;
			root->left = p;
			printf("是否为学生添加成绩(1.是  2.否):");
			scanf("%d", &cas);
			if (cas == 1)
			{
				addscore(p);
			}
		}
		else
		{
			insertstu(root->left, str, no);
		}
	}
	else
	{
		if (root->right == NULL)
		{
			S *p = (S *)malloc(sizeof(S));	//节点创建
			strcpy(p->name, str);
			strcpy(p->num, no);
			p->left = NULL;
			p->right = NULL;
			p->head = NULL;
			p->count = 0;
			root->right = p;
			printf("是否为学生添加成绩(1.是  2.否):");
			scanf("%d", &cas);
			if (cas == 1)
			{
				addscore(p);
			}
		}
		else
		{
			insertstu(root->right, str, no);
		}
	}
}

void scoreprint(O *head) //输出成绩信息
{
	if (head == NULL)
		return;
	scoreprint(head->left);
	printf("%s:%d\t\t", head->subject, head->chengji);
	scoreprint(head->right);
}

void stuprint(S* root) //输出学生信息
{
	printf("学号:%s\t\t姓名:%s\t\t", root->num, root->name);
	scoreprint(root->head);
	printf("\n");
}

int searchscore(O* head, char str[], S* p) //查找科目是否存在
{
	if (head == NULL)
		return 0;
	else if (strcmp(head->subject, str) == 0)
	{
		p->p = head;
		return 1;
	}
	else
		return searchscore(head->left, str, p) || searchscore(head->right, str, p);//否则返回子节点的结果 
}

void show(S* root, int cas, char str[]) //查找学生信息
{
	if (root == NULL)
		return;
	show(root->left, cas, str);
	if (cas == 1 && strcmp(root->num, str) == 0) //按学号查找
		stuprint(root);
	if (cas == 2 && strcmp(root->name, str) == 0) //按姓名查找
		stuprint(root);
	if (cas == 3)
	{
		O *temp;
		if (searchscore(root->head, str, root)) //该学生有本科目的成绩 
		{	
			stuprint(root);
		}
	}
	if (cas == 5 && strcmp(root->num, str) == 0)
		addscore(root);
	show(root->right, cas, str);
}

void addso(S *root) //给单人加成绩
{
	char str[20];
	printf("请输入学生学号：");
	scanf("%s", str);
	show(root, 5, str);
}

void search(S* root) //查找函数
{
	int cas;
	int no;
	char str[20];
	S* p;
	for (int i = 1; i < 50; i++)
		printf("-");
	printf("\n");
	printf("[1].按学号查找\n");
	printf("[2].按姓名查找\n");
	printf("[3].按科目查找\n");
	//printf("[4].显示所有信息\n"); 
	for (int i = 1; i < 50; i++)
		printf("-");
	printf("\n");
	printf("请输入操作：");
	scanf("%d", &cas);
	if (cas == 1)
		printf("请输入学生学号：");
	if (cas == 2)
		printf("请输入学生姓名：");
	if (cas == 3)
		printf("请输入学生科目：");
	scanf("%s", str);
	show(root, cas, str);
}

void allshow(S* root) //显示所有学生信息/学号排序
{
	if (root == NULL)
	{
		return;
	}
	allshow(root->left);
	stuprint(root);
	allshow(root->right);
}

void stusort(S* root) //按个人成绩排序
{
	char str[20];
	printf("请输入学生学号：");
	scanf("%s", str);
	show(root, 1, str);
}

void sortbyname(S* root) //按姓名排序 ※
{
	char str[20];
	S* a[100], *temp; //
	int i = 0, j = 0, k;
	if (root != NULL)
		a[i++] = root;
	else
	{
		printf("排序错误，请输入学生。\n");
		return;
	}
	while (j<i)
	{
		if (a[j]->left != NULL)
			a[i++] = a[j]->left;
		if (a[j]->right != NULL)
			a[i++] = a[j]->right;
		j++;
	}
	for (j = 0; j < i; j++)
	{
		for (k = 0; k < i - j - 1; k++) 
		{
			if (strcmp(a[k]->name, a[k + 1]->name) > 0)
			{
				temp = a[k];
				a[k] = a[k + 1];
				a[k + 1] = temp;
			}
		}
	}
	for (i = 0; i < j; i++)
	{
		stuprint(a[i]);
	}
}

void sortbysub(S* root) //按科目排序
{
	char str[20];
	S* a[100], *temp;
	int i = 0, j = 0, k;
	printf("请输入科目：");
	scanf("%s", str);
	if (root != NULL) 
	{
		a[i++] = root;
	}
	else
	{
		printf("无内容，请重新输入！\n");
		return;
	}
	while (j < i) 
	{
		if (a[j]->left != NULL)
			a[i++] = a[j]->left;
		if (a[j]->right != NULL)
			a[i++] = a[j]->right;
		if (searchscore(a[j]->head, str, a[j])) // ※
			j++;
		else			// ※
		{
			i--;
			for (k = j; k < i; k++)
			{
				a[k] = a[k + 1];
			}
		}
	}
	for (j = 0; j < i; j++)
	{
		for (k = 0; k < i - j - 1; k++)
		{
			if (a[k]->p->chengji < a[k + 1]->p->chengji)
			{
				temp = a[k];
				a[k] = a[k + 1];
				a[k + 1] = temp;
			}
		}
	}
	for (j = 0; j < i; j++)
	{
		printf("学号:%s\t\t姓名:%s\t\t", a[j]->num, a[j]->name);
		printf("%s\t\t%d\n", a[j]->p->subject, a[j]->p->chengji);
		
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