C语言数据结构实例讲解单链表的实现

#pragma once
 
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
 
typedef int SLDataType;
 
//链表的创建
typedef struct SListNode
{
	SLDataType data;//val
	struct SListNode* next;//存储下一个结点的地址
}SListNode,SLN;
 
//打印链表
void SListPrint(SListNode* phead);
 
//尾插
void SListPushBack(SListNode** pphead, SLDataType x);
 
//头插
void SListPushFront(SListNode** pphead, SLDataType x);
 
//尾删
void SListPopBack(SListNode** pphead);
 
//头删
void SListPopFront(SListNode** pphead);
 
//查找
SListNode* SListFind(SListNode* phead, SLDataType x);
 
//在pos位置之前插入
void SListInsert(SListNode** pphead, SListNode* pos, SLDataType x);
 
//删除pos位置
void SListErase(SListNode** pphead, SListNode* pos);
 
//在pos位置之后插入
void SlistInserAfter(SListNode* pos, SLDataType x);
 
//删除pos后的值
void SlistEraseAfter(SListNode* pos);
 
//用完销毁
void SListDestroy(SListNode** pphead);

void SListPrint(SListNode* phead)
{
	assert(phead);
 
	SListNode* cur = phead;
 
	if (cur == NULL)
	{
		printf("SList is NULL\n");
	}
 
	while (cur != NULL)
	{
		printf("%d->", cur->data);
		cur = cur->next;
	}
	printf("NULL\n");
}

SListNode* BuySList(SLDataType x)
{
	SListNode* newnode = (SListNode*)malloc(sizeof(SListNode));
	if (newnode == NULL)
	{
		printf("malloc fail\n");
		exit(-1);
	}
	else
	{
		newnode->data = x;
		newnode->next = NULL;
	}
	return newnode;
}

void SListPushBack(SListNode** pphead, SLDataType x)
{
	assert(pphead);
 
	SListNode* newnode = BuySList(x);
	
	if (*pphead == NULL)
	{
		*pphead = newnode;
	}
	else
	{
		//找尾
		SListNode* tail = *pphead;
		while (tail->next != NULL)
		{
			tail = tail->next;
		}
		//走完循环找到尾
		tail->next = newnode;
	}
 
}

void SListPushFront(SListNode** pphead, SLDataType x)
{
	assert(pphead);
 
	SListNode* newnode = BuySList(x);
 
	newnode->next = *pphead;
	*pphead = newnode;
 
}

void SListPopBack(SListNode** pphead)
{
	assert(pphead);
 
	//当链表只有一个结点时
	if (*pphead == NULL)
	{
		printf("SListNode is NULL\n");
		return;
	}
	//当链表只有一个结点时
	else if ((*pphead)->next == NULL)
	{
		free(*pphead);
		*pphead = NULL;
	}
	//当链表有多个结点时
	else
	{
		SListNode* tail = *pphead;
		while (tail->next->next != NULL)
		{
			tail = tail->next;
		}
		free(tail->next);
		tail->next = NULL;
	}
}

void SListPopFront(SListNode** pphead)
{
	assert(pphead);
 
	if (*pphead == NULL)
	{
		printf("SList is NULL\n");
		return;
	}
	else
	{
		SListNode* next = (*pphead)->next;
		free(*pphead);
		*pphead = next;
	}
}

SListNode* SListFind(SListNode* phead, SLDataType x)
{
	assert(phead);
 
	SListNode* cur = phead;
	while (cur != NULL)
	{
		if (cur->data == x)
		{
			return cur;
		}
		//如果没找到就往下走
		cur = cur->next;
	}
	//循环完成后还没找到就说明链表中没有该值
	return NULL;
}

void SListInsert(SListNode** pphead, SListNode* pos, SLDataType x)
{
	assert(pphead);
	assert(pos);
 
	//pos是第一个位置
	if (pos == *pphead)
	{
		SListPushFront(pphead, x);
	}
 
	//pos不是第一个位置
	else
	{
		SListNode* prev = *pphead;
		while (prev->next != pos)
		{
			prev = prev->next;
		}
		SListNode* newnode = BuySList(x);
		prev->next = newnode;
		newnode->next = pos;
	}
}

void SListErase(SListNode** pphead, SListNode* pos)
{
	assert(pphead);
	assert(pos);
 
	//1、头结点为空
	if (*pphead == NULL)
	{
		printf("SList is NULL\n");
		return;
	}
	//2、删除第一个结点
	else if (pos == *pphead)
	{
		SListPopFront(pphead);
	}
	//3、其他结点
	else
	{
		SListNode* prev = *pphead;
		while (prev->next != pos)
		{
			prev = prev->next;
		}
		prev->next = pos->next;
		free(pos);
		pos = NULL;
	}
}

void SListInsertAfter(SListNode* pos, SLDataType x)
{
	assert(pos);
 
	SListNode* newnode = BuySList(x);
	SListNode* next = pos->next;
 
	pos->next = newnode;
	newnode->next = next;
 
    //下面这种方式也可以
	/*SListNode* newnode = BuySList(x);
	newnode->next = pos->next;
	pos->next = newnode;*/
}

void SListEraseAfter(SListNode* pos)
{
	assert(pos);
 
	SListNode* next = pos->next;
	if (next)
	{
		pos->next = next->next;
		free(next);
		next = NULL;
	}
	
}

void SListDestroy(SListNode** pphead)
{
	assert(pphead);
 
	SListNode* cur = *pphead;
	while (cur)
	{
		SListNode* next = cur->next;
		free(cur);
		cur = next;
	}
 
	*pphead = NULL;
}

#include "SList.h"
 
void test1()
{
	SListNode* slist = NULL;
 
	//测试尾插
	SListPushBack(&slist, 1);
	SListPushBack(&slist, 2);
	SListPushBack(&slist, 3);
	SListPushFront(&slist, 5);
	SListPushFront(&slist, 4);
	SListPrint(slist);
 
	//测试头插
	SListPushFront(&slist, 5);
	SListPushFront(&slist, 4);
	SListPrint(slist);
 
	//测试尾删
	SListPopBack(&slist);
	SListPopBack(&slist);
	SListPrint(slist);
 
	//测试头删
	SListPopFront(&slist);
	SListPopFront(&slist);
	SListPopFront(&slist);
	SListPrint(slist);
 
	//测试查找
	SListNode* ret1 = SListFind(slist, 5);
	printf("%d\n", ret1->data);
	/*SListNode* ret2 = SListFind(slist, 2);
	printf("%d\n", ret2->data);*/
 
	//pos前插测试
	SListNode* pos = SListFind(slist, 1);
	if (pos)
	{
		SListInsert(&slist,pos,3);
	}
	SListPrint(slist);
	pos = SListFind(slist, 1);
	if (pos)
	{
		SListInsert(&slist, pos, 10);
	}
	SListPrint(slist);
 
	//删除pos测试
	pos = SListFind(slist, 10);
	if (pos)
	{
		SListErase(&slist, pos);
	}
	SListPrint(slist);
 
	//测试在pos后插入
	pos = SListFind(slist, 3);
	if (pos)
	{
		SListInsertAfter(pos, 6);
	}
	SListPrint(slist);
	pos = SListFind(slist, 1);
	if (pos)
	{
		SListInsertAfter(pos, 8);
	}
	SListPrint(slist);
 
	//测试删除pos后的值
	pos = SListFind(slist, 1);
	if (pos)
	{
		SListEraseAfter(pos);
	}
	SListPrint(slist);
 
}
 
int main()
{
	
	test1();
 
	return 0;
}