C双向链表代码实现

C双向链表代码实现

 基于单向链表做了一些修改，实现双向链表，记录一下

#include 
#include 

struct node{
	int data;
	struct node* next;
	struct node* prev;
};

struct node* creatlist()
{
	struct node* headnode = (struct node*)malloc(sizeof(struct node));
	headnode->next = NULL;
	headnode->prev = NULL;
	return headnode;
}

struct node* creatnode(int data)
{
	struct node* newnode = (struct node*)malloc(sizeof(struct node));
	newnode->next = NULL;
	newnode->prev = NULL;
	newnode->data = data;
	return newnode;
}

void insertnode(struct node* list,int data)
{
	struct node* newnode = creatnode(data);
	struct node* head = list;
	
	if(head->next == NULL) {
		newnode->next = NULL;
		newnode->prev = head;
		head->next = newnode;
	}else{
		newnode->next = head->next;
		newnode->prev = head;
		head->next->prev = newnode;
		head->next = newnode;	
	}
}

void printlist(struct node* list)
{
	struct node* pmove = list->next;
	if(!pmove)
		printf("链表为空n");
	while(pmove != NULL)
	{
		printf("%d",pmove->data);
		pmove = pmove->next;
	}
	printf("n");
}

void delnode(struct node* list, int data)
{
	struct node* posnode = list->next;
	
	if(posnode == NULL)
		printf("链表为空n");
	else {
		while(posnode->data != data) {
			posnode = posnode->next;
			if(posnode == NULL){
				printf("找不到对应结点n");
				return;
			}
		}
		
		if(posnode->next != NULL){
			posnode->prev->next = posnode->next;
			posnode->next->prev = posnode->prev;
			free(posnode);
		} else {
			posnode->prev->next = NULL;
		}
			
	}
}

int main()
{
	struct node *list;
	list = creatlist();
	insertnode(list,6);
	insertnode(list,1);
	insertnode(list,3);
	insertnode(list,4);
	printlist(list);
	delnode(list,1);
	delnode(list,4);
	delnode(list,3);
	delnode(list,6);
	printlist(list);
    return 0;
}

 输出结果：