C语言|控制台|学生成绩管理系统|动态链表|无文件读写

#include<stdio.h>
#include<stdlib.h>
#define LEN sizeof(struct student)
int main_menu();
int fun_choose();
int fun1();
int fun2(struct student *head);
int fun3(struct student *Head);
int fun4(struct student * Head);
int fun5(struct student * Head);
int fun6(struct student *p);
int fun7(struct student *p);
int fun8(struct student *p);
int num = 0;      //用来存放节点数量的全局变量
struct student
{
	unsigned int number;                             //无符号整型学号
	float score;                                     //浮点型分数
	struct student *next;
}*create(int n), *start=NULL, *end=NULL;                                         
int main()                                           //主函数
{
	main_menu();
	return 0;
}
struct student *create(int n)                        //创建动态链表的函数
{
	struct student *head, *p1, *p2;
	head = p1 = p2 = (struct student*)malloc(LEN);
	printf("\n     [用TAB键分隔学号与成绩，ENTER键以输入下个学生的信息]\n\n| 学号 | 成绩 |\n");
	scanf("%d%f", &p1->number, &p1->score);
	while (n - 1 > 0)
	{
		p1 = (struct student*)malloc(LEN);
		p2->next = p1;
		scanf("%d%f", &p1->number, &p1->score);
		p2 = p1;
		n--;
	}
	end = p2;
	p2->next = NULL;
	return head;
}
int main_menu()              //<学生成绩管理系统>主菜单
{
	int i;
	printf("\n            学生成绩管理系统\n\n+****************************************+\n|1、录入成绩                             |\n|2、输出成绩                             |\n|3、修改成绩                             |\n|4、删除记录                             |\n|5、统计成绩                             |\n|6、成绩排序                             |\n|7、追加记录                             |\n|8、清空记录                             |\n|0、退出                                 |\n+****************************************+\n\n请选择：");
	scanf("%d", &i);
	switch (i)
	{
	case 0:exit(0); break;
	case 1:fun1(); break;
	case 2:fun2(start); break;
	case 3:fun3(start); break;
	case 4:fun4(start); break;
	case 5:fun5(start); break;
	case 6:fun6(start); break;
	case 7:fun7(end); break;
	case 8:fun8(start); break;
	default:printf("\n\n    错误！无法实现该功能！请重新选择！\n\n\n\n\n\n\n\n"); main_menu();
	}
	return 0;
}
int fun_choose()                  //回到主菜单或退出程序的函数
{
	int z;
	printf("\n\n[输入1返回主菜单，输入0关闭程序]\n\n请选择：");
	scanf("%d", &z);
	if (z == 0)
		exit(0);
	else
	if (z == 1)
	{
		printf("\n\n\n\n\n\n\n\n");
		main_menu();
	}
	else
	{
		printf("\n     [错误的指令]");
		fun_choose();
	}
	return 0;
}
int fun1()                        //从无开始录入记录的函数
{
	if (start != NULL)
	{
		printf("\n     [已有记录，无需重新录入]");
		fun_choose();
	}
	printf("\n\n\n需要录入信息的学生个数为：");
	scanf("%d", &num);
	while (num <= 0)
	{
		printf("\n     [错误！人数必须是正整数，请重新输入人数！]\n\n需要录入信息的学生个数为：");
		scanf("%d", &num);
	}
	start = create(num);
	printf("\n     [录入完成]");
	fun_choose();
	return 0;
}
int fun2(struct student *head)                      //输出所有记录的函数
{
	if (head == NULL)
	{
		printf("\n     [未录入记录]");
		fun_choose();

	}
	else
	{
		printf("\n\n\n\n\n\n|  学号 | 成绩  |\n");
		while (head != NULL)
		{
			if (head->number != 0)
				printf("|%d	|%3.2f	|\n", head->number, head->score);
			head = head->next;
		}
		printf("\n     [输出完成]");
		fun_choose();
	}
	return 0;
}
int fun3(struct student *Head)                      //修改指定目标成绩的函数
{
	struct student *p;
	unsigned int i;
	printf("\n\n\n输入要修改成绩的学生的学号：");
	scanf("%d", &i);
	if (Head == NULL)
	{
		printf("\n     [未录入记录]");
		fun_choose();
	}
	if (Head != i && Head->next == NULL)
	{
		printf("\n     [未找到该学生的记录]");
		fun_choose();
	}
	if (Head->number == i)
	{
		printf("\n请输入要修改的成绩：");
		scanf("%f", &Head->score);
		printf("\n     [修改完成]");
		fun_choose();
	}
	for (p = NULL; Head != NULL; Head = Head->next)
	{
		p = Head->next;
		if (p->number == i)
		{
			printf("\n请输入要修改的成绩：");
			scanf("%f", &p->score);
			printf("\n     [修改完成]");
			fun_choose();
		}
		if (p->number != i && p->next == NULL)
		{
			printf("\n     [未找到该学生的记录]");
			fun_choose();
		}
	}
	return 0;
}

int fun4(struct student *Head)             //删除指定目标记录的函数
{
	struct student *p;
	unsigned int i;
	printf("\n\n\n输入要删除记录的学生的学号：");
	scanf("%d", &i);
	if (Head == NULL)
	{
		printf("\n     [未录入记录]");
		fun_choose();
	}
	else
		if (Head->next == NULL && Head->number != i)
		{
			printf("\n     [未找到该学生的记录]");
			fun_choose();
		}
	if (Head->number == i )
	{
		start = Head->next;
		free(Head);
		num--;
		if (Head->next == NULL)
			end = start = NULL;
		printf("\n     [已删除该学生的记录]");
		fun_choose();
	}
	else
		for (p = NULL; Head != NULL; Head = Head->next)
		{
			p = Head->next;
			if (p->number == i && p->next != NULL)
			{
				Head->next = p->next;
				free(p);
				num--;
				printf("\n     [已删除该学生的记录]");
				fun_choose();
			}
			else
				if (p->number == i && p->next == NULL)
				{
					end = Head;
					Head->next = NULL;
					free(p);
					num--;
					printf("\n     [已删除该学生的记录]");
					fun_choose();
				}
			if (p->number != i && p->next == NULL)
			{
				printf("\n     [未找到该学生的记录]");
				fun_choose();
			}
		}
	return 0;
}
int fun5(struct student * Head)            //统计所有成绩的函数
{
	int a = 0, b = 0, c = 0, e = 0, n = 0;
	float x, y, z = 0.0, f;
	if (Head == NULL)
	{
		printf("\n     [未录入记录]");
		fun_choose();
	}
	else
	{
		printf("\n\n");
		printf("请输入及格线：");
		scanf("%f", &x);
		printf("\n请输入优秀线：");
		scanf("%f", &y);
		for (; Head != NULL; Head = Head->next)
		{
			a++;
			z = z + Head->score;
			f = z / a;
			if (Head->score >= y) e++;
			if (Head->score >= x) c++;
			else n++;
		}
		printf("\n\n\n\n\n");
		printf("平均分为:      %.2f\n及格人数为:    %d\n及格率为:      %.1f%c\n优秀人数为:    %d\n不及格人数为:  %d\n", f, c, 100.0*c / a, 37, e, n);
		fun_choose();
	}
	return 0;
}
int fun6(struct student *p)                     //对所有成绩进行排序的函数
{
		unsigned int i, j, a;
		float t;
		struct student *q, *d = p;
		if (num == 0 || num == 1)
		{
			printf("\n     [目前录入的学生数无法排序]");
			fun_choose();
		}
		else
		{
			for (i = 0; i < num; i++)
			{
				p = d;
				q = p->next;
				for (j = 0; j < num - i - 1; j++)
				{
					if (p->score < q->score)
					{
						a = p->number;
						p->number = q->number;
						q->number = a;
						t = p->score;
						p->score = q->score;
						q->score = t;
					}
					p = q;
					q = q->next;
				}
			}
			printf("\n     [已完成排序]");
			fun_choose();
		}
		return 0;
	}
int fun7(struct student *p)                     //在末尾追加单个记录的函数
{
	struct student *p1;
	if(p == NULL)
	{
		printf("\n     [目前还未录入记录，无法进行追加]");
		fun_choose();
	}
	else
	{
		p1 = p->next = (struct student*)malloc(LEN);
		printf("\n     [用TAB键分隔学号与成绩，ENTER键以输入下个学生的信息]\n\n| 学号 | 成绩 |\n");
		scanf("%d%f", &p1->number, &p1->score);
		p1->next = NULL;
		end = p1;
		num++;
		printf("\n     [录入完成]");
		fun_choose();
	}
	return 0;
}
int fun8(struct student *p)                     //清空所有记录的函数
{
	struct student *p1;
	int i;
	printf("\n     [确定要清空记录吗？按1确定，按0否定]\n\n请选择：");
	scanf("%d", &i);
	if (i == 0)
		fun_choose();
	else
		if (i == 1)
		{
			while (p != NULL)
			{
				p1 = p->next;
				free(p);
				num--;
				p = p1;
			}
			start = end = NULL;
			printf("\n     [已清空记录]");
			fun_choose();
		}
		else
			printf("\n     [无对应的选项！请重新选择！]\n");
	fun8(start);
	return 0;
}