单链表增删改查

//头插
void SListPushFront(SListNode** pplist, SLTDateType x)
{
	SListNode* pcurr = BuySListNode(x);
	if(*pplist==NULL)
	{
		*pplist = pcurr;
	}
	else
	{
         pcurr->next = *pplist;//这里会写成pcurr->next = pplist->next;
		 *pplist = pcurr;
	}
}

//调用
#include "slist.h"
#include
int main()
{
	SListNode *plist=NULL;
	
	SListPushFront(&plist,9);
	SListPushFront(&plist,8);

	SListPrint(plist);
	system("pause");
	return 0;
}

注意： 指向下一个节点时，不要写成pcur->next = pplist->next;如上图绿色 箭头方向

完整代码

//1.test.c
#include "slist.h"
#include
int main()
{
	SListNode *plist=NULL;
	SListPushBack(&plist,10);
	SListPushBack(&plist,11);
	SListPushBack(&plist,12);
	SListPushBack(&plist,13);
	SListPushFront(&plist,9);
	SListPushFront(&plist,8);

	//SListPopBack(&plist);
	//SListPopBack(&plist);

	SListPopFront(&plist);

	SListDestory(plist);
	plist=NULL;//销毁后需要将结构体指针变量置空

	SListPrint(plist);

	system("pause");
	return 0;
}


//slist.h
#include
#include
typedef int SLTDateType;
typedef struct SListNode
{
	SLTDateType data;
	struct SListNode* next;
}SListNode;

// 动态申请一个末节点
SListNode* BuySListNode(SLTDateType x);
// 单链表打印
void SListPrint(SListNode* plist);
// 单链表尾插
void SListPushBack(SListNode** pplist, SLTDateType x);
// 单链表的头插
void SListPushFront(SListNode** pplist, SLTDateType x);
// 单链表的尾删
void SListPopBack(SListNode** pplist);
// 单链表头删
void SListPopFront(SListNode** pplist);
// 单链表查找
SListNode* SListFind(SListNode* plist, SLTDateType x);
// 单链表在pos位置之后插入x
// 分析思考为什么不在pos位置之前插入？
void SListInsertAfter(SListNode* pos, SLTDateType x);
// 单链表删除pos位置之后的值
// 分析思考为什么不删除pos位置？
void SListEraseAfter(SListNode* pos);
// 单链表的销毁
void SListDestory(SListNode* plist);

//3.slist.c
#include "slist.h"


SListNode* BuySListNode(SLTDateType x)
{
	SListNode* ps = (SListNode*)malloc(sizeof(SListNode));
	ps->data=x;
	ps->next=NULL;
	return ps;
}
void SListPrint(SListNode* plist)
{
	SListNode* cur = plist;
	while(cur!=NULL)
	{
		printf("%d ",cur->data);
		cur = cur->next;
	}
}

void SListPushBack(SListNode** pplist, SLTDateType x)
{
	SListNode*list = BuySListNode(x);

	if(*pplist==NULL)
	{
		*pplist =list;
	}
	else
	{
		SListNode* tail=*pplist;
		while (tail->next != NULL)
		{
			tail = tail->next;
		}
		tail->next=list;
	}
}

void SListPushFront(SListNode** pplist, SLTDateType x)
{
	SListNode* pcurr = BuySListNode(x);
	if(*pplist==NULL)
	{
		*pplist = pcurr;
	}
	else
	{
         pcurr->next = *pplist;//这里会写成pcurr->next = pplist->next;
		 *pplist = pcurr;
	}
}

void SListPopBack(SListNode** pplist)
{
	/*SListNode* tail = *pplist;
	while(tail->next->next!=NULL)
	{
	tail = tail->next; 
	}
	free(tail->next);
	tail->next=NULL;*/


	/***********方法二********/
	SListNode* tailPrev = NULL;
	SListNode* tail = *pplist;
	if(tail->next==NULL)
	{
		free(tail);
		*pplist=NULL;//这里如果使用tail=NULL;会置空失败
	}else
	{
		while (tail->next != NULL)
		{
			tailPrev = tail;
			tail = tail->next;
		}
		free(tail);//释放尾结点所在节点内存，地址在上一节点next中寻找
		tailPrev->next = NULL;
	}
}

void SListPopFront(SListNode** pplist)
{
	SListNode* plist = (*pplist)->next;
	free(*pplist);
	*pplist = plist;
}

SListNode* SListFind(SListNode* plist, SLTDateType x)
{
	SListNode* cur = plist;
	while (cur)
	{
		if (cur->data == x)
			return cur;

		cur = cur->next;
	}
	return NULL;
}
void SListDestory(SListNode* plist)
{
	SListNode* next=NULL;
	while(plist!=NULL)
	{
		next = plist->next;
		free(plist);
		plist = next;
	}
}