双链表相关操作

#include <stdio.h>#include <stdlib.h>typedef struct DLnode{int data;struct DLnode *prior, *next;}DLnode, *DLinkList;/*初始化双链表*/void Init_DLinkList(DLinkList &L){L = (DLnode*)malloc(sizeof(DLnode));    //初始化头结点L->prior = L->next = NULL;    //初始化头尾指针}/*在双链表L的第i个元素前面插入值为 x的新节点*/void Inser_DLinkList(DLinkList &L, int i, int x){int j = 0;DLinkList p = L, s;while(p != NULL && j < i){j++;p = p->next;}if(p == NULL){printf("第j个节点不存在\n");}else{s = (DLnode*)malloc(sizeof(DLnode));s->data = x;s->prior = p->prior;s->next = p;p->prior->next = s;p->prior = s;}}/*删除第i个数据元素*/void Delete_DLinkList(DLinkList &L, int i){int j = 0;DLinkList p = L;while(p != NULL && j < i){j++;p = p->next;}if(p == NULL){printf("第j个节点不存在\n");}else{p->prior->next = p->next;if(p->next != NULL){p->next->prior = p->prior;}    free(p);}}/*打印双链表*/void Print_DLinkList(DLinkList &L){DLnode* p;p = L->next;//L是头指针，p指向第一个节点，开始打印while(p != NULL){printf("%d\n", p->data);p = p->next;}}int main(){DLinkList L;Init_DLinkList(L);DLnode *L1 = (DLnode*)malloc(sizeof(DLnode));L1->data = 1;L->next = L1;L1->prior = L;L1->next = NULL;printf("初始化一个节点，双链表是\n");    Print_DLinkList(L);printf("插入元素后，双链表是\n");Inser_DLinkList(L, 1, 4);Inser_DLinkList(L, 2, 5);Print_DLinkList(L);printf("删除元素后，双链表是\n");Delete_DLinkList(L, 2);Print_DLinkList(L);return 0;}