这个小代码是我凭自己对指针和链表的理解和认识，自己实现的，没有参考其他人的代码，如果有相同的地方，那真的只是巧合，代码我在ubuntu 15.04下测试通过，可能存在很多错误和漏洞．

doublelist.c

/************************************************************************* > File Name: doublelist.c > Author: ChenYiLiang > Mail: chenyiliangex@163.com > Created Time: Sat 21 Mar 2015 07:32:22 PM CST ************************************************************************/ #include <stdio.h> #include <stdlib.h> #include <string.h> struct userdata{ int userid; char username[30]; struct userdata *previous; struct userdata *next; }; struct userdata *header; size_t scanf_id; char scanf_name[30]; int yesno; int deletePosition; int alterPosition; int alterId; char alterName[30]; int searchPosition; FILE *ptr_fpid; /*向链表中插入数据*/ int insert_list(struct userdata *header, size_t position, char name[], size_t id); /*删除链表中指定的节点*/ int delete_node(struct userdata *header, size_t position); /*修改指定位置的节点信息*/ int alter_node(struct userdata *header, size_t position, size_t id, char name[]); /*查找链表中的数据*/ struct userdata *search_node(struct userdata *header, size_t position); /*遍历链表*/ int travel_list(struct userdata *header); /*判断链表是空*/ int isempty(struct userdata *header); /*将链表结构写入文件*/ int write_into_file(struct userdata *header, FILE *fp); /*从文件读取数据放到链表中*/ int read_from_file(struct userdata *header, FILE *fp); int main(){ struct userdata *header_node = (struct userdata *)malloc(sizeof(struct userdata)); header_node -> previous = NULL; header_node -> next = NULL; read_from_file(header_node, ptr_fpid); travel_list(header_node); while(1){ //scanf("%*[^n]"); //scanf("%*c"); //scanf("%*[^n]"); printf("please input id - "); scanf("%d", &scanf_id); //scanf("%*c"); //scanf("%*[^n]"); printf("please input your name - "); scanf("%s", scanf_name); printf("%d - %snn", scanf_id, scanf_name); //isempty(header_node); /*0表示默认插入到链表的尾部*/ insert_list(header_node, 0, scanf_name, scanf_id); //write_into_file(header_node, ptr_fpid); //isempty(header_node); printf("input anymore - "); scanf("%d", &yesno); if(yesno == -1){ break; } scanf("%*c"); scanf("%*[^n]"); // travel_list(header_node); } getchar(); //printf("delete position data - "); //scanf("%d", &deletePosition); //delete_node(header_node, deletePosition); // printf("alter data for position - "); // scanf("%d", &alterPosition); // printf("please inout new id - "); // scanf("%d",&alterId); // printf("please input new name - "); // scanf("%s", alterName); // alter_node(header_node, alterPosition, alterId, alterName); write_into_file(header_node, ptr_fpid); travel_list(header_node); printf("nn"); printf("please input position to search - "); scanf("%d", &searchPosition); struct userdata *searchData = search_node(header_node, searchPosition); printf("%dn", searchData -> userid); printf("%sn", searchData -> username); return 0; } /* 插入节点 */ int insert_list(struct userdata *header, size_t position, char name[], size_t id ){ struct userdata *temp_newuser = header; struct userdata *getMemory = (struct userdata *)malloc(sizeof(struct userdata)); getMemory -> userid = id; strncpy(getMemory -> username, name, 30); /*当position == 0时,表示默认插入到链表的尾部*/ if(0 == position){ if(NULL != temp_newuser -> next){ while(NULL != temp_newuser -> next){ temp_newuser = temp_newuser -> next; } } } /*当position > 1时则寻找合适的位置插入*/ if(1 <= position){ for(int i = 0; i <= position; i++){ /*当执行此处的代码时表示,链表已经到达尾部或者是空链表*/ if(NULL == temp_newuser -> next){ break; } temp_newuser = temp_newuser -> next; } } getMemory -> previous = temp_newuser; if(temp_newuser -> next == NULL){ temp_newuser -> next = getMemory; getMemory -> next = NULL; }else{ temp_newuser -> next -> previous = getMemory; getMemory -> next = temp_newuser -> next; temp_newuser -> next = getMemory; } return 0; } /*删除链表中指定的节点*/ int delete_node(struct userdata *header, size_t position){ int is_empty = isempty(header); if(0 == is_empty){ printf("this si a empty list!nn"); return -1; } struct userdata *deleteNode = header; for(int i = 0; i < position; i++ ){ /*当执行此处的代码时表示,链表已经到达尾部或者是空链表*/ if(NULL == deleteNode -> next){ break; } deleteNode = deleteNode -> next; } /**/ deleteNode -> next -> previous = deleteNode -> previous; deleteNode -> previous -> next = deleteNode -> next; free(deleteNode); return 0; } /*修改指定位置的节点信息*/ int alter_node(struct userdata *header, size_t position, size_t id, char name[]){ int isEmpty = isempty(header); if(0 == isEmpty){ printf("this is a empty listnn"); return -1; } struct userdata *alterNode = header; for(int i = 0; i < position; i++ ){ /*当执行此处的代码时表示,链表已经到达尾部或者是空链表*/ if(NULL == alterNode -> next){ break; } alterNode = alterNode -> next; } alterNode -> userid = id; strncpy(alterNode -> username, name, 30); return 0; } /*查找链表中的数据*/ struct userdata *search_node(struct userdata *header, size_t position){ int isEmpty = isempty(header); if(0 == isEmpty){ printf("this is a empty!n"); return NULL; } struct userdata *searchNode = header; for(int i = 0; i < position; i++){ if(NULL == searchNode -> next){ break; } searchNode = searchNode -> next; } return searchNode; } /*遍历链表*/ int travel_list(struct userdata *header){ struct userdata *travel = header; if(NULL == travel -> next){ printf("This is a empty list!!n"); return 1; } for(travel = travel -> next ; ; travel = travel -> next){ printf("%dn",travel -> userid); printf("%sn", travel -> username); if(NULL == travel -> next){ break; } } return 1; } /*判断链表是空*/ int isempty(struct userdata *header){ if(header -> next == NULL){ return 0; }else{ return 1; } } /*将链表结构写入文件*/ int write_into_file(struct userdata *header, FILE *fp){ fp = fopen("listdata", "wb"); if(NULL == fp){ perror("open file failed when write into file!"),exit(-1); } printf("come into write!n"); for(struct userdata *move = header -> next; ; move = move -> next){ fwrite(move,sizeof(struct userdata), 1, fp); if(NULL == move -> next){ break; } } fclose(fp); fp = NULL; return 0; } /*从文件读取数据放到链表中*/ int read_from_file(struct userdata *header, FILE *fp){ struct userdata *readfile = header; fp = fopen("listdata", "rb"); if(NULL == fp){ perror("open file failed when read - "); return -1; } while(1){ struct userdata *newread = (struct userdata *)malloc(sizeof(struct userdata)); fread(newread, sizeof(struct userdata), 1, fp); if(feof(fp)){/*当读取到文件的尾部时．跳出循环*/ break; } readfile -> next = newread; newread -> next = NULL; newread -> previous = readfile; readfile = newread; } fclose(fp); fp = NULL; return 0; }

C语言实现双向链表删除节点、插入节点、双向输出等操作

#include<cstdio> #include<cstdlib> typedef struct DoubleLinkedList { int data; struct DoubleLinkedList *pre; struct DoubleLinkedList *next; }DlinkedList_Node; //建立链表 DlinkedList_Node* createDLink() { DlinkedList_Node *head,*p,*s; int x; head = (DlinkedList_Node*)malloc(sizeof(DlinkedList_Node)); p = head; while(1) { printf("please input the data: n"); scanf("%d",&x); if(x != 65535) { s = (DlinkedList_Node*)malloc(sizeof(DlinkedList_Node)); s ->data = x; s-> pre = p; p->next = s; p=s; } else { printf("n数据输入结束n"); break; } } p->next = NULL; head = head ->next; head->pre = NULL; return head; } //顺序、反序打印链表 void printDLink(DlinkedList_Node *head) { DlinkedList_Node *p,*s; p = head; printf("正序输出双向链表：n"); while(p) { printf("%d ",p->data); s = p; p = p->next; } printf("n 逆序输出双向链表: n"); while(s) { printf("%d ",s->data); s = s->pre; } printf("n n"); } //删除一个结点 DlinkedList_Node* deleteDlinkedList_Node(DlinkedList_Node *head,int i) { DlinkedList_Node *p; p = head; if(p->data == i) { head = p->next; head->pre = NULL; free(p); return head; } while(p) { if(p->data == i) { p->pre->next = p->next; p->next->pre = p->pre; free(p); return head; } p = p->next; } printf("没有找到想要删除的数据n"); return head; } //插入一个结点 DlinkedList_Node* insertDlinkedList_Node(DlinkedList_Node *head,int i) { DlinkedList_Node *p,*temp; p = head; temp = (DlinkedList_Node*)malloc(sizeof(DlinkedList_Node)); temp ->data = i; if(i < p->data)//比头结点数据小，插入到链表头部 { head = temp; head->next = p;//此处p为原来的head head->pre = NULL; p->pre = head;//此处p为原来的head return head; } while(p != NULL && i > p->data)//寻找合适的插入位置 { p = p->next; } if(i < p->data)//在链表中间某处找到合适插入位置 { temp ->next = p; temp ->pre = p->pre; p ->pre->next = temp; p ->pre = temp; return head; } else//没有找到合适的位置，只有将数据插入到链表尾部 { p->next = temp; //遍历到链表尾部，p==NULL temp ->pre = p; temp ->next = NULL; return head; } } int main() { DlinkedList_Node *head; head = createDLink(); printDLink(head); head = insertDlinkedList_Node(head,1012); head = deleteDlinkedList_Node(head,1991); printDLink(head); } /***************************** 运行结果如下： please input the data: 1991 please input the data: 1992 please input the data: 2013 please input the data: 2014 please input the data: 512 please input the data: 420 please input the data: 65535 数据输入结束 正序输出双向链表： 1991 1992 2013 2014 512 420 逆序输出双向链表: 420 512 2014 2013 1992 1991 正序输出双向链表： 1012 1992 2013 2014 512 420 逆序输出双向链表: 420 512 2014 2013 1992 1012 ******************************/

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