一、链表简介

链表是一种物理存储结构上非连续的存储结构，数据元素的逻辑顺序是通过链表中的指针链接次序实现的。

链表在结构上的分类：

虽然链表有多种结构类型，但是我么在实际开发中常用的只有两种结构：

1. 无头单向非循环链表：结构简单，通常不单独使用，而是作为其他数据结构的子结构，如哈希桶、图的邻接表……
2. 带头双向循环链表：结构最复杂，功能最全面，使用效率高

下例代码是无头单向非循环链表的实现，设计思路：

1. 每个ListNode节点都包含一个数据和一个next指针，next指针指向下一个节点
2. 当pList == NULL 的时候，代表这个链表为空，没有任何数据
3. 链表最后一个节点的next指针一定是NULL
4. 当函数涉及数据增删时，传入的参数为二级指针 ListNode** ppList

二、SingleList.h

#define _CRT_SECURE_NO_WARNINGS 1#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>typedef int DataType;typedef struct ListNode
{DataType data;struct ListNode* next;
}ListNode;bool Empty(ListNode* plist)
{return plist == NULL;
}void Print(ListNode* plist)
{ListNode* cur = plist;while (cur != NULL){printf("%2d -> ", cur->data);cur = cur->next;}printf("NULL\n");
}// 动态申请一个节点
ListNode* BuyNode(DataType x)
{ListNode* node = (ListNode*)malloc(sizeof(ListNode));node->data = x;node->next = NULL;return node;
}// 尾插
void PushBack(ListNode** pplist, DataType x)
{assert(pplist);ListNode* node = BuyNode(x);// 插入链表的第一个节点if (*pplist == NULL){*pplist = node;return;}// cur指针通过循环遍历找到链表的尾结点ListNode* cur = *pplist;while (cur->next != NULL){cur = cur->next;}cur->next = node;
}// 头插
void PushFront(ListNode** pplist, DataType x)
{assert(pplist);ListNode* node = BuyNode(x);if (*pplist == NULL){*pplist = node;return;}node->next = *pplist;*pplist = node;
}// 尾删
void PopBack(ListNode** pplist)
{if (Empty(*pplist)){printf("链表为空，尾删失败\n");return;}ListNode* cur = *pplist;ListNode* prev = cur;while (cur->next != NULL){prev = cur;cur = cur->next;}free(cur);cur = NULL;prev->next = NULL;
}// 头删
void PopFront(ListNode** pplist)
{if (Empty(*pplist)){printf("链表为空，尾删失败\n");return;}ListNode* cur = *pplist;*pplist = cur->next;free(cur);cur = NULL;
}// 查找，返回第一个元素x的节点
ListNode* Find(ListNode* plist, DataType x)
{ListNode* cur = plist;while (cur != NULL){if (cur->data == x)return cur;cur = cur->next;}return NULL;
}// 在pos后面插入新节点，pos节点由Find函数获得
void InsertAfter(ListNode* pos, DataType x)
{if (pos == NULL){printf("pos为空，数据插入失败\n");return;}ListNode* node = BuyNode(x);node->next = pos->next;pos->next = node;
}// 删除pos节点
void Delete(ListNode** pplist, ListNode* pos)
{if (pos == NULL){printf("pos为空，数据删除失败\n");return;}if (Empty(*pplist)){printf("单链表已为空，Delete失败\n");return;}ListNode* cur = *pplist;ListNode* prev = NULL;while (cur){if (cur->data == pos->data && prev == NULL){// 删除第一个节点*pplist = pos->next;free(pos);pos = NULL;return;}if (cur->data == pos->data){prev->next = pos->next;free(pos);pos = NULL;return;}prev = cur;cur = cur->next;}
}// 销毁链表
void Destroy(ListNode** pplist)
{while (*pplist){ListNode* cur = *pplist;*pplist = cur->next;free(cur);cur = NULL;}printf("链表销毁成功\n");
}

三、test.c

#define _CRT_SECURE_NO_WARNINGS 1#include "SingleList.h"int main()
{ListNode* plist = NULL;// 尾插数据PushBack(&plist, 1);PushBack(&plist, 3);PushBack(&plist, 5);PushBack(&plist, 7);Print(plist);// 头插数据PushFront(&plist, 2);PushFront(&plist, 4);PushFront(&plist, 6);PushFront(&plist, 8);Print(plist);// 尾删数据PopBack(&plist);PopBack(&plist);PopBack(&plist);Print(plist);// 头删数据PopFront(&plist);PopFront(&plist);PopFront(&plist);Print(plist);// 在查找的元素后面插入节点InsertAfter(Find(plist, 1), -1);InsertAfter(Find(plist, 2), -2);InsertAfter(Find(plist, -2), 22);Print(plist);// 删除查找到的节点Delete(&plist, Find(plist, -2));Delete(&plist, Find(plist, -1));Delete(&plist, Find(plist, 22));Delete(&plist, Find(plist, 100)); // pos为空，数据删除失败！Print(plist);// Delete删空链表Delete(&plist, Find(plist, 2));Delete(&plist, Find(plist, 1));Delete(&plist, Find(plist, 1)); // pos为空，数据删除失败！Print(plist);// 销毁链表，先插入数据测试PushBack(&plist, 1);PushBack(&plist, 2);PushBack(&plist, 3);Print(plist); // 1 -> 2 -> 3 -> NULLDestroy(&plist); // 链表销毁成功Print(plist);
}