线性表的链式存储
1. 基本概念
2.设计与实现
- 在C语言中可以用结构体来定义链表中的指针域–数据节点/业务节点
链表中的表头结点也可以用结构体实现–表头结点
插入操作
带头结点、位置从0的单链表返回链表中第3个位置处元素的值
LinkListNode* LinkList_Get(LinkList* list, int pos){ int i = 0; TLinkList *tList = (TLinkList *)list; LinkListNode *current = NULL; LinkListNode *ret = NULL; if (list==NULL ||pos<0 || pos>=tList->length) { return NULL; } current = (LinkListNode *)tList; for (i=0; i<pos; i++) { current = current->next; } ret = current->next; return ret ;}
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—返回第三个位置的
移动pos次以后,当前指针指向哪里?
答案:指向位置2,所以需要返回 ret = current->next;
备注:
循环遍历时, 遍历第1次,指向位置0
遍历第2次,指向位置1
遍历第3次,指向位置2
遍历第n次,指向位置n-1;
所以如果想返回位置n的元素的值,需要怎么做
ret = current->next;
此问题是:指向头结点的指针移动n次指向第n-1个元素。
- 删除
3.实现代码
#ifndef _MYLINKLIST_H_#define _MYLINKLIST_H_#include <stdlib.h>#include <stdio.h>#include <memory.h>typedef void LinkList;typedef struct _tag_LinkListNode{ struct _tag_LinkListNode* next;}LinkListNode;LinkList* LinkList_Create();void LinkList_Destroy(LinkList* list);void LinkList_Clear(LinkList* list);int LinkList_Length(LinkList* list);int LinkList_Insert(LinkList* list, LinkListNode* node, int pos);LinkListNode* LinkList_Get(LinkList* list, int pos);LinkListNode* LinkList_Delete(LinkList* list, int pos);#endif
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#include "TLinkList.h"typedef struct _tag_LinkList{ LinkListNode head; int length;}TLinkList;LinkList* LinkList_Create(){ TLinkList * tmp = NULL; tmp = (TLinkList*)malloc(sizeof(TLinkList)); if (NULL == tmp) { printf("malloc error!\n"); return NULL; } memset(tmp, 0, sizeof(TLinkList)); return tmp;}void LinkList_Destroy(LinkList* list){ if (list != NULL) { free(list); list = NULL; } else { printf("list is error!\n"); } return ;}void LinkList_Clear(LinkList* list){ TLinkList * tmp = NULL; if (list == NULL) { printf("list is error!\n"); return; } tmp = (TLinkList*)list; tmp->length = 0; tmp->head.next= NULL; return ;}int LinkList_Length(LinkList* list){ TLinkList * tmp = NULL; if (list == NULL) { printf("list is error!\n"); return -1; } tmp = (TLinkList*)list; return tmp->length;}int LinkList_Insert(LinkList* list, LinkListNode* node, int pos){ TLinkList * tmp = NULL; LinkListNode * current = NULL; int i = 0; if (list == NULL || node == NULL || pos < 0) { printf("argv is error!\n"); return -2; } tmp = (TLinkList*)list; if (pos >= tmp->length) { pos = tmp->length; } current = &(tmp->head); for (i = 0; i < pos && current->next != NULL; i++) { current = current->next; } node->next = current->next; current->next = node; tmp->length++; return 0;}LinkListNode* LinkList_Get(LinkList* list, int pos){ TLinkList * tmp = NULL; LinkListNode * current = NULL; int i = 0; if (list == NULL || pos < 0) { printf("argv is error!\n"); return NULL; } tmp = (TLinkList*)list; if (pos >= tmp->length) { pos = tmp->length; } current = &(tmp->head); for (i = 0; i < pos && current->next != NULL; i++) { current = current->next; } return current->next;}LinkListNode* LinkList_Delete(LinkList* list, int pos){ TLinkList * tmp = NULL; LinkListNode * current = NULL; LinkListNode * del_res = NULL; int i = 0; if (list == NULL || pos < 0) { printf("argv is error!\n"); return NULL; } tmp = (TLinkList*)list; if (pos >= tmp->length) { pos = tmp->length; } current = &(tmp->head); for (i = 0; i < pos && current->next != NULL; i++) { current = current->next; } del_res = current->next; current->next = del_res->next; tmp->length--; return del_res;}
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#include "TLinkList.h"typedef struct Teacher{ LinkListNode node; char name[64]; int age;}Teacher;int main(){ Teacher t1, t2, t3; int length, i = 0; LinkList *list = NULL; t1.age = 31; t2.age = 32; t3.age = 33; list = LinkList_Create(); length = LinkList_Length(list); LinkList_Insert(list, (LinkListNode *)&t1, LinkList_Length(list)); LinkList_Insert(list, (LinkListNode *)&t2, LinkList_Length(list)); LinkList_Insert(list, (LinkListNode *)&t3, LinkList_Length(list)); for (i = 0; i<LinkList_Length(list); i++) { Teacher *tmp = (Teacher *)LinkList_Get(list, i); if (tmp != NULL) { printf("age:%d ", tmp->age); } } while (LinkList_Length(list) > 0) { Teacher *tmp = (Teacher *)LinkList_Delete(list, 0); if (tmp != NULL) { printf("age:%d ", tmp->age); } } LinkList_Destroy(list); system("pause"); return 0;}
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4.优缺点
- 无需一次性定制链表的容量
- 插入和删除操作无需移动数据元素
- 数据元素必须保存后继元素的位置信息
- 获取指定数据的元素操作需要顺序访问之前的元素