C语言学习---记录结构体链表排序失败的三种方案。。。

研究了三晚的结构体链表的创建、插入、删除、输出、释放。期间想要写出结构体链表排序的功能。。。然而我手中三本C语言的书都没有交排序。。。于是自己想尝试下。。。

走上了不归路啊啊啊。。。考纲都不考我研究这个干啥！！！

弄了两晚上的排序，自己写了两种思路，网上找了一种思路，还是没有搞定。。吐了吐了。。

还写了另一种错误的删除方案。。。妈哒。。。

待日后有时间再来解决，倘若有大佬看到能指出我这个沙雕小白的错误那就很是开心了！

附上成功的创建、插入、删除、输出、释放的代码

源代码：

#pragma warning(disable:4996)
#include
#include
#include

#define LEN sizeof(struct STU)

struct STU
{
	char num[7];
	float score;
	struct STU* next;
};

struct STU* Create_link(int size);
struct STU* Sort_link(struct STU* head);
void Print_link(struct STU* head);
void Add_link(struct STU** head, struct STU stu);
void Del_link(struct STU** head, char* no);
void Destroy_link(struct STU** head);

void main()
{
	int n;
	struct STU* head = NULL, stu;// *no=NULL;
	char no[7];
	printf("本次输入信息的学生个数:n");
	scanf("%d", &n);
	head = Create_link(n);
	//head = Sort_link(head);
	printf("n信息输入结果如下:n");
	Print_link(head);
#if(1)
	printf("n输入需要插入的学生信息:n");
	scanf("%s %f", stu.num, &stu.score);
	Add_link(&head, stu);
	printf(" 信息插入后的结果:n");
	Print_link(head);
#endif
#if(1)
	printf("n输入要删除信息的学号:n");
	scanf("%s",no);
	Del_link(&head, no);
	printf("n信息删除后的结果:n");
	Print_link(head);
#endif
	Destroy_link(&head);
}

struct STU* Create_link(int size)
{
	struct STU* head=NULL, * p1, * p2=NULL;
	int i = 0;
	while (i < size)
	{
		p1 = (struct STU*)malloc(LEN);
		p1->next = NULL;
		printf("请输入第%d个学生的学号和成绩:n", i + 1);
		scanf("%s %f", p1->num,&p1->score);
		if (head== NULL)
		{
			head = p1;
			p2 = p1;
		}
		else
		{
			p2->next = p1;
			p2 = p1;
		}
		i++;
	}
	return (head);
}


void Print_link(struct STU* head)
{
	struct STU* p;
	p = head;
	while(p != NULL)
	{
		printf("%s %.1fn", p->num, p->score);
		p = p->next;
	}
}

void Add_link(struct STU** head, struct STU stu)
{
	struct STU* p, * p1, * p2;
	p = (struct STU*)malloc(LEN);
	strcpy(p->num, stu.num);
	p->score = stu.score;
	p->next= NULL;
	p1 = p2 = *head;
	while (p1 != NULL && strcmp(p->num, p1->num) > 0)
	{
		p2 = p1;
		p1 = p1->next;
	}
	if (p1 == NULL)//说明已经移动到链表末尾
	{
		p2->next = p;
		p->next = NULL;//链表在末尾加入
	}
	else if (strcmp(p->num, p1->num) < 0)//添加的链表学号若比p1小
	{
		if (*head == p1)//链表在表首加入
		{
			*head = p;
			p->next = p1;//或(*head)->next = p1;
		}
		else
		{
			p2->next = p;
			p->next = p1;//链表在中间加入
		}
	}
}

#if(1)
void Del_link(struct STU** head, char* no)
{
	struct STU * p, * p1;
	int n;
	char nostr[7];
	p1 = p = *head;
	while (strcmp((p->num), no) != 0)
	{
		p1 = p;
		p = p->next;//为了找到目标学号
	}
	if (p == NULL)
	{
		printf("该链表没有指定的删除信息,是否重新输入？n");
		scanf("%d", &n);
		if (n == 1)
		{
			printf("请重新输入学号:");
			scanf("%s", nostr);
			strcpy(*no, nostr);
			p1 = p = *head;
		}

	}
	if (strcmp((p->num), no) == 0)
	{
		if (p == *head)
		{
			p1 = p->next;
			*head = p1;
			free(p);
		}
		else if (p!= NULL)
		{
			p1->next = p->next;
			free(p);
		}
	}
		

}
#endif


void Destroy_link(struct STU** head)
{
	struct STU* p;
	while (*head != NULL)
	{
		p = *head;
		*head = (*head)->next;
		free(p);
	}
	*head = NULL;
}

 排序的错误代码：

//排序代码，第一种方案，失败,主要因为char型num无法直接比大小 void Sort_link(struct STU * head, int size)
#if(0)
void Sort_link(struct STU* head,int n)
{
	struct STU* temp=NULL, *temp2=NULL,* p1, *p2;
	int i, j;
	if (n > 1)
	{
		p1 = head;
		p2 = p1->next;
		if (n < 3)
		{
			if (p1->num > p2->num)
			{
				head = p2;
				p2->next = p1;
				p1->next = NULL;
			}
		}
		if (n >= 3)
		{
			for (i = 0; i < n - 1; i++)
			{
				for (j = 0; j < n - 1 - i; j++)
				{
					if (p1->num > p2->num)
					{
						if (head == p1)
						{
							head = p2;
							temp = p2;
							p1->next = p2->next;
							p2->next = p1;
							p2 = p1->next;
						}
						else if (p2->next == NULL)
						{
							temp->next = p2;
							p2->next = p1;
							p1->next = NULL;
							p1 = head;
							p2 = p1->next;
							temp = NULL;
						}
						else
						{
							temp->next = p2;
							p1->next = p2->next;
							p2->next = p1;
							temp = p2;
							p2 = p1->next;
						}
					}
					if (p1->num <= p2->num)
					{
						if (head == p1)
						{
							temp = p2->next;
							p1 = p2;
							p2 = temp;
							temp = head;
						}
						else if (p2->next == NULL)
						{
							temp = NULL;
							p1 = head;
							p2 = p1->next;
						}
						else
						{
							temp2 = temp;
							temp = p2->next;
							temp2 = p1;
							p1 = p2;
							p2 = temp;
							temp = temp2;
							temp2 = NULL;
						}
					}
				}
			}
		}

	}

}
#endif
//排序代码，第二种方案,失败。。。。。。。。void Sort_link(struct STU** head);
#if(0)
void Sort_link(struct STU** head, int n)
{
	struct STU* temp = NULL, * p1, * p2;
	if (n > 1)
	{
		p1 = *head;
		p2 = p1->next;
		if (n < 3)//只有两行数据的时候交换
		{
			while (strcmp(p1->num , p2->num) > 0)
			{
				*head = p2;
				p2->next = p1;
				p1->next = NULL;
			}
		}
		if (n >= 3)
		{
			while (strcmp(p1->num, p2->num) > 0)
			{
				if ((*head) == p1)//在链首交换
				{
					*head = p2;
					temp = p2->next;
					p2->next = p1;
					p1->next = temp;
					temp = p2;
					p2 = p1->next;
				}
				else if (p2->next == NULL)//在链尾交换
				{
					temp->next = p2;
					p2->next = p1;
					p1->next = NULL;
				}
				else//在链中交换
				{
					temp->next = p2;
					temp = p2->next;
					p1->next = temp;
					p2->next = p1;
					temp = p2;
					p2 = p1->next;
				}
			}

		}

	}
	return;
}
#endif
//排序代码，第三种方案,失败。。。。。。。。struct STU* Sort_link(struct STU* head);
#if(0)
struct STU* Sort_link(struct STU* head)
{
	struct STU* p, * q, * tail,*flag;
	char temp_num=NULL;
	int temp_score;
	if (head == NULL)
	{
		return (head);
	}
	else
	{
		tail = NULL;
		flag = NULL;
		p = q = NULL;
		while (flag != head)
		{
			tail = flag;
			flag = head;
			p = q = head;
			while(p->next!=tail)
			{
				q = p->next;
				if (strcmp(p->num, q->num) > 0)
				{
					strcpy(temp_num, p->num);
					strcpy( p->num,q->num);
					strcpy(q->num, temp_num);
					temp_score = p->score;
					p->score = q->score;
					q->score = temp_score;
					flag = p->next;
				}
				p = p->next;
			}
		}
		return (head);
	}
}
#endif

删除功能的错误代码：

#if(0)
void Del_link(struct STU** head, char* no)
{
	struct STU* p1, * p = *head;
	if (strcmp((*head)->num, no) == 0)
	{
		*head = (*head)->next;
		free(p);
	}
	else
	{
		p1 = *head;
		while (p != NULL && strcmp((p->num), no) != 0)
		{
			p1 = p;
			p = p->next;
		}
		if (p == NULL)
		{
			printf("该链表无指定删除的学号");
		}
		if (p != NULL && strcmp((p->num), no) == 0)
		{
			p1->next = p->next;
			free(p);
		}

	}
}
#endif