C语言实现单向链表的反转

C语言实现单向链表的反转

作者：大宝同学

时间：2015-12-22

测试环境：VC++6.0    gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)

/*
	描述：将单向链表反转
	作者：大宝同学
	时间：2015-12-22
*/

#include 
#include 

struct list
{
	struct list *p;
	int n;
};

typedef struct list List;

/*
	通过结构体List 创建一个链表
*/
List *create_list()
{
	int i = 0;
	List *head = NULL;
	List *pnote = NULL;
	pnote = (List *)malloc(sizeof(List));
	head = pnote;

	for(i=0; i<4; i++)
	{
		pnote->n = i + 1;
		pnote->p = (List *)malloc(sizeof(List));
		pnote = pnote->p;
	}
	pnote->n = i + 1;
	pnote->p = NULL;

	return head;
}
/*
	释放链表空间
*/
void free_list(List **head)
{
	List *pnote = *head;

	while((*head)->p != NULL)
	{
		pnote = (*head)->p;
		free(*head);
		*head = pnote;
	}
	*head = NULL;
}
/*
	打印链表
*/
void print_list(List *head)
{
	if(head == NULL)
	{
		printf("head is NULL!\n");
		return ;
	}
	
	do
	{
		printf("%d ", head->n);
		head = head->p;
	}
	while(head != NULL);

	printf("\n");
}
/*
	将链表反转
*/
List *list_reverse(List *head)
{
	List *new_head = NULL;
	List *pnote = NULL;

	if(head == NULL)
	{
		printf("head is NULL!\n");
		return head;
	}

	new_head = head->p;
	head->p = NULL;

	do
	{
		pnote = new_head;
		new_head = pnote->p;
		pnote->p = head;
		head = pnote;
	}
	while(new_head != NULL);

	return pnote;
}

int main()
{
	List *head = create_list();

	print_list(head);

	head = list_reverse(head);

	print_list(head);

	free_list(&head);

	print_list(head);

	printf("*** Debug test ***\n");

	return 0;
}