C言語の一方向チェーンの作成、解放、挿入、削除、反転操作の練習

/**********************************************************************************
* @brief:               、  、  、  、  、  、     
* @author: wuchuan.
* @date: 2013.11.5
***********************************************************************************/

#include 
#include 
#include 

struct node
{
	int num;
	struct node *next;
};

struct node *head = NULL;

void create_link(int n)
{
	int i = 0;
	struct node *cur = NULL;

	while (i++ < n)
	{
		struct node *tmp = NULL;
		tmp = (struct node *)malloc(sizeof(struct node));
		if (tmp != NULL)
		{
			tmp->num = i;
			tmp->next = NULL;
			if (head == NULL)
				head = cur = tmp;
			else
			{
				cur->next = tmp;
				cur = cur->next;
			}
		}
	}
}

void free_link(struct node *head)
{
	struct node *tmp = NULL;
	struct node *cur = head;

	while (cur)	
	{
		tmp = cur;
		cur = cur->next;
		free(tmp);
		tmp = NULL;
	}
}

void print_link(struct node *head)
{
	struct node *cur = NULL;

	for (cur = head; cur; cur = cur->next)
		printf("cur->num = %d
", cur->num);
	return;
}

int get_link_len(struct node *head)
{
	int len = 0;
	struct node *cur = NULL;
	
	for (cur = head; cur; cur = cur->next)
		len++;
	return len;
}

#if (0)
/*    ok */
int insert_node(struct node **head, int num)
{
	struct node *tmp = NULL;
	struct node *cur = *head;
	if (*head == NULL)
		return -1;

	tmp = (struct node *)malloc(sizeof(struct node));
	if (tmp == NULL)
		return -2;
	tmp->num = num;
	
	if ((*head)->num >= num)
	{	
		tmp->next = *head;
		*head = tmp;
		return 0;
	}
	while (cur)
	{
		if (cur->next == NULL)
		{
			cur->next = tmp;
			tmp->next = NULL;
			return 0;
		}
		else if (cur->next->num >= num)
		{
			tmp->next = cur->next;
			cur->next = tmp;
			return 0;
		}
		cur = cur->next;
	}
	return -3;
}
#endif

int insert_node(struct node **head, int num)
{
	struct node *cur, *pre, *pnew;
	cur = pre = pnew = NULL;

	if (*head == NULL)
		return -1;
	pnew = (struct node *)malloc(sizeof(struct node));
	if (pnew == NULL)
		return -2;
	pnew->num = num;
	pnew->next = NULL;
	
	if ((*head)->num >= num)
	{
		pnew->next = *head;
		*head = pnew; 
		return 0;
	}
	pre = *head;
	cur = (*head)->next;
	while (cur)
	{
		if (cur->num >= num)
		{	
			pnew->next = cur;
			pre->next = pnew;
			return 0;
		}
	pre = cur;
	cur = cur->next;
	}
	/*      */
	pre->next = pnew;
	return 0;
}

void delete_node(struct node **head, int num)
{
	struct node *pre, *cur, *p;
	pre = cur = p = NULL;

	while (*head != NULL && (*head)->num == num)
	{
		p = *head;
		*head = (*head)->next;
		free(p);
	}
	pre = *head;
	cur = (*head)->next;
	while (cur)
	{
		if (cur->num == num)
		{
			p = cur;
			cur = cur->next;
			pre->next = cur;
			free(p);
			continue;
		}
		pre = cur;
		cur = cur->next;
	}
	return;
}

struct node *reverse_link(struct node **head)
{
	if (*head == NULL || (*head)->next == NULL)
		return *head;
	struct node *pre, *cur, *next;
	
	pre = *head;
	cur = (*head)->next;
	(*head)->next = NULL;
	while (cur)
	{
		//next       next  
		next = cur->next;
		//     next            (  )
		cur->next = pre;
		pre = cur;
		cur = next;
	}
	//  head
	*head = pre;
	return *head;
}

/**
 * test demos
 * gcc link.c -o link -g -Wall
 */
int main(int argc, char *argv[])
{
	if (argc != 4)
	{
		printf("Usage: %s [count] [number1] [number2]
", argv[0]);
		printf("------[count] indicates how many nodes you want to create
");
		printf("------[number1] indicates which node you want to delete
");
		printf("------[number2] indicates a num node you want to insert
");
		return -1;
	}
		
	printf("Now will create %d nodes in the link
", atoi(argv[1]));
	create_link(atoi(argv[1]));

	print_link(head);
	printf("
*****link len = %d*****
", get_link_len(head));

	printf("Now will delete num=%d node in the link
", atoi(argv[2]));
	delete_node(&head, atoi(argv[2]));

	print_link(head);
	printf("
*****link len = %d*****
", get_link_len(head));

	printf("Now will insert num=%d node into the link
", atoi(argv[3]));
	insert_node(&head, atoi(argv[3]));

	print_link(head);
	printf("
*****link len = %d*****
", get_link_len(head));

	printf("Now reverse the link
");
	head = reverse_link(&head);
	
	print_link(head);
	printf("
*****link len = %d*****
", get_link_len(head));

	free_link(head);
	return 0;
}