双向链表操作：建立，初始化，遍历，清空

双向链表操作：建立，初始化，遍历，清空

 

双向链表常见操作如下：建立链表，初始化链表，遍历链表，清空链表，销毁链表，插入节点，删除节点，查找某节点等。

 

////2021年3月10日17点35分

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


typedef  struct Node
{
	int node_data;
	struct Node *prev;
	struct Node *next;
}pNode;

struct Node *InitList(pNode *head,int n);
void TraversalList(pNode *head);
void DeleteList(pNode *head);
int ClearList(pNode *head);



////链表的各项操作
int main(void)
{
	int n = 4;
	pNode *head = NULL;
	pNode *tail = NULL;
	
	head = (pNode *)malloc(sizeof(pNode));
//	printf("head addr: %p\n",head);


	
	//初始化链表并赋值,返回尾节点last
	tail = InitList(head,n);
//	printf("head addr: %p\n",head);
//	printf("tail addr: %p\n",tail);
	
	//打印为第一个元素和最后一个元素
//	printf("%d %d \n", head->next->node_data, tail->node_data);
    printf("Please traversal all element of the list:\n");
	TraversalList(head);
	
//	DeleteList(head);
    ClearList(head); 
	
	printf("\nPlease traversal all element of the list:\n");
	TraversalList(head);
	
	return 0;
}


////链表建立及初始化
struct Node *InitList(pNode *head,int n)
{
	int i = 0;
	pNode *p = NULL;
	pNode *q = NULL;
	
	p = (pNode *)malloc(sizeof(pNode));
	
	
	if((NULL == p))
	{
		printf("内存空间已满\n:");
		exit(0);
	}
	
	p = head;
	p ->node_data = 0;
	p ->prev = NULL;
	p ->next = NULL;
	
	////链表初始化并赋值
	for(i=0;i<n;i++)
	{
		q = (pNode *)malloc(sizeof(pNode));
		if((NULL == q))
		{
			printf("内存空间已满\n:");
			exit(0);
		}
		
		
		q ->node_data = i+1;
		q ->prev = p;
		q ->next = NULL;
		p ->next = q;
		
		p = q; //指向尾节点
		
	//	printf("当前节点序号为 %dth\n",i+1);
	//	printf("当前节点数值为 %d\n", p ->node_data);
	}
	
//	free(p);
//	free(q);
	
	return p;
}


////遍历链表
void TraversalList(pNode *head)
{
	int j = 0;
	
	while(NULL != (head))
	{
		printf("当前节点数序号为: %d\n", j);
		printf("当前节点数值为: %d\n", head ->node_data);
		
		head = head ->next; 
		j++;
	}
	
}

////销毁链表 —— 头节点也删除
void DeleteList(pNode *head)
{
	pNode *p = NULL;
	
	p = (pNode *)malloc(sizeof(pNode));	
	if((NULL == p))
	{
		printf("内存空间已满\n:");
		exit(0);
	}
	
	if(NULL == head)
	{
		exit(0);
	}
	
	while(NULL != (head))
	{
		p = head ->next;
		free(head);
		head = p;
	} 

}


////清空链表 —— 保留头节点
int ClearList(pNode *head)  
{  
    pNode *p,*q;  
    if(head==NULL)
    {
        return 0;  
    }
    
    p=head->next;  
    while(p!=NULL)  
    {  
        q=p->next;  
        free(p);  
        p=q;  
    }  
    head->next=NULL;  
    return 1;  
}