双向链表以及双向循环链表头插头删尾插尾删操作代码

双向链表

head.h

#ifndef __HEAD_H
#define __HEAD_H


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

enum passble{FALSE=-1,SUCCESS};
typedef char datatype;

//双向链表节点的结构体
typedef struct Node
{
	//数据域：数据元素
	datatype data;
	//指针域：上一个节点的地址
	struct Node *prev;
	//指针域：下一个节点的地址
	struct Node *next;
}*Doublelink;

Doublelink create_node();

Doublelink insert_head(datatype element, Doublelink head);

void output(Doublelink head);

Doublelink delete_head(Doublelink head);

Doublelink insert_tail(datatype element, Doublelink head);

Doublelink delete_tail(Doublelink head);

#endif

main.c

#include "head.h"

int main(int argc, const char *argv[])
{
	Doublelink head = NULL; //定义双向链表头结点
	int n;
	printf("please enter n:");
	scanf("%d", &n);
	datatype element;

	//头插
	for(int i=0; i<n; i++)
	{
		printf("please enter %d element:", i+1);
		//getchar();
		//element = getchar();
		scanf(" %c", &element);
		head = insert_head(element, head);
	}

	output(head);

	//头删
	head = delete_head(head);
	output(head);

	//尾插
	int x;
	printf("please enter x:");
	scanf("%d", &x);
	for(int i=0; i<x; i++)
	{
		printf("please enter %d element:", i+1);
		//getchar();
		//element = getchar();
		scanf(" %c", &element);
		head = insert_tail(element, head);
	}
	output(head);

	//尾删
	head = delete_tail(head);
	output(head);
  
	return 0;
}

test.c

#include "head.h"

//创建新节点
Doublelink create_node()
{
    Doublelink s = (Doublelink)malloc(sizeof(struct Node));
    if(s == NULL )
        return NULL;

    //新节点数据域的初始化
    s->data = 0;
    //新节点的指针域初始化
    s->next = NULL;
    s->prev = NULL;
    return s;
}

//双向链表的头插
Doublelink insert_head(datatype element, Doublelink head)
{
    
    //创建一个新节点
    Doublelink s = create_node();
    s->data = element;

    //1.链表为空
    if(head == NULL)
        head = s;
    //2.链表不为空(节点数>=1)
    else
    {
        s->next = head;
        head->prev = s;
        head = s;
    }
    return head;
}

void output(Doublelink head)
{
    //判断链表是否为空
    if(head == NULL)
    {    
        printf("The linked list is empty\n");
        return ;
    }
    //循环输出正向
    Doublelink p = head;
    while(p->next != NULL)
    {
        printf("%c ", p->data);
        p = p->next;
    }
    printf("%c\n", p->data);
}

//头删
Doublelink delete_head(Doublelink head)
{
    //判断链表是否为空
    if(head == NULL)
        return NULL;
    //头删
    else
    {

        Doublelink del = head;
        head = head->next;
         free(del);
        del = NULL;
        return head;
    }
}

//尾插
Doublelink insert_tail(datatype element, Doublelink head)
{
    //创建一个新节点
    Doublelink s = create_node();
    s->data = element;
    //1.判断链表是是否为空
    if(head == NULL)
        head = s;
    //2.链表不为空(节点数>=1)
    else
    {
        Doublelink p = head;
        while(p->next)
        {
            p = p->next;
        }
        p->next = s;
        s->prev = p;
    }
    
    s->next = NULL;
    return head;
}

//尾删
Doublelink delete_tail(Doublelink head)
{
    //判断链表是否为空
    if(head == NULL)
        return NULL;
    //尾删
    Doublelink p = head;
    while(p->next)
    {
        p = p->next;
    }

    if(p->prev != NULL)
    {
        p->prev->next = NULL;
    }
    else
        head = NULL;
    free(p);
        
    return head;
}

双向循环链表

head.h 与main.c参考双向链表代码

test.c

#include "head.h"

//创建新节点
Doublelink create_node()
{
	Doublelink s = (Doublelink)malloc(sizeof(struct Node));
	if(s == NULL )
		return NULL;

	//新节点数据域的初始化
	s->data = 0;
	//新节点的指针域初始化
	s->next = s;
	s->prev = s;
	return s;
}

//双向链表的头插
Doublelink insert_head(datatype element, Doublelink head)
{
	
	//创建一个新节点
	Doublelink s = create_node();
	s->data = element;

	//1.链表为空
	if(head == NULL)
		head = s;
	//2.链表不为空(节点数>=1)
	else
	{
		Doublelink rear = head->prev;
		s->next = head;
		head->prev = s;
		head = s;
		rear->next = head;
		head->prev = rear;
	}
	return head;
}

void output(Doublelink head)
{
	//判断链表是否为空
	if(head == NULL)
	{	
		printf("The linked list is empty\n");
		return ;
	}
	//循环输出正向
	Doublelink p = head;
	do
	{
		printf("%c ", p->data);
		p = p->next;
	}while(p != head);
	printf("\n");
}

//头删
Doublelink delete_head(Doublelink head)
{
	//判断链表是否为空
	if(head == NULL)
		return NULL;
	//头删
	Doublelink del = head;
	if(head->next == head)
	{
		//只有一个节点删除后为空链表
		head = NULL;
	}
	else
	{
		head->prev->next = head->next;
		head->next->prev = head->prev;
		head = head->next;
	}
}

//尾插
Doublelink insert_tail(datatype element, Doublelink head)
{
	//创建一个新节点
	Doublelink s = create_node();
	s->data = element;
	//1.判断链表是是否为空
	if(head == NULL)
		head = s;
	//2.链表不为空(节点数>=1)
	else
	{
		Doublelink rear = head->prev;
		s->next = head;
		s->prev = rear;
		rear->next = s;
		head->prev = s;
	}
	
	return head;
}

//尾删
Doublelink delete_tail(Doublelink head)
{
	//判断链表是否为空
	if(head == NULL)
		return NULL;
	//尾删
	Doublelink p = head;
	if(head->next == head)
	{
		free(head);
		head = NULL;
	}
	else
	{
		p = head->prev;
		p->prev->next = head;
		head->prev = p->prev;
		free(p);
	}	
	return head;
}