双向链表的C实现

本文用C语言实现了双向链表的create 创建、display 遍历、search 查找节点、del 删除节点、insert 插入节点，实现及测试程序如下：

#include <stdio.h>
#include <stdlib.h>

typedef struct dlink
{
	int num;
	struct dlink *prior;
	struct dlink *next;
}NODE;

NODE *create(int n)
{
	NODE *pf = NULL, *pb = NULL, *head = NULL;
	int i = 0;
	for(i=0; i<n; i++)
	{
		pb = (NODE *)malloc(sizeof(NODE));
		printf("please input num:\n");
		scanf("%d", &pb->num);
		if(i == 0)
		{
			head = pb;
			pb->next = NULL;
			pb->prior = NULL;
			pf = pb;
		}
		else
		{
			pf->next = pb;
			pb->prior = pf;
			pf = pb;
		}
	}
	pf->next = NULL;
	return head;
}

void display(NODE *head)
{
	NODE *pb = head;
	while(pb->next != NULL)
	{
		printf("%d ", pb->num);
		pb = pb->next;
	}
	printf("%d\n", pb->num);
}

NODE *search(NODE *head, int data)
{
	NODE *mov = head;
	while(mov != NULL)
	{
		if(mov->num == data)
		{
			printf("%d\n", mov->num);
			return head;
		}
		mov = mov->next;
	}
	printf("node not found!\n");
	return head;
}

NODE *del(NODE *head, int data)
{
	NODE *pf = head, *pb = head;
	while(pb->next!=NULL && pb->num!=data)
	{
		pf = pb;
		pb = pb->next;
	}
	if(pb->num == data)
	{
		if(pb == head)
		{
			pb->next->prior = NULL;
			head = pb->next;
		}
		else
		{
			if(pb->next == NULL)
				pf->next = NULL;
			else
			{
				pf->next = pb->next;
				pb->next->prior = pf;
			}
		}
		free(pb);
	}
	return head;
}

NODE *insert(NODE *head, int data)
{
	NODE *pi, *pb = head, *pf = head;
	pi = (NODE *)malloc(sizeof(NODE));
	pi->num = data;
	if(pb == NULL)
	{
		head = pi;
		pi->next = NULL;
		pi->prior = NULL;
		return head;
	}
	while(pb->next!=NULL && pb->num < pi->num)
	{
		pf = pb;
		pb = pb->next;
	}
	if(pb->num >= pi->num)
	{
		if(pb == head)
		{
			pi->next = pb;
			pb->next->prior = pi;
			head = pi;
			pi->prior = NULL;
			return head;
		}
		else
		{
			pf->next = pi;
			pi->prior = pf;
			pi->next = pb;
			pb->prior = pi;
			return head;
		}
	}
	else
	{
		pb->next = pi;
		pi->prior = pb;
		pi->next = NULL;
	}
	return head;
}

int main(int argc, char *argv[])
{
	NODE *head = NULL;

	head = create(5);
	display(head);

	head = search(head, 3);

	head = del(head, 3);
	head = search(head, 3);

	head = insert(head, 3);
	head = search(head, 3);

	return 0;
}