C语言之单链表增删查改

目录

一、创建新节点

二、增加新节点

1.尾插

2.头插

三、删除节点

1.尾删

2.头删

四、查找链表中的某个节点

五、在某节点前插入节点

六、删除某节点

七、全部代码段

1.test.h

2.SList.cpp

3.test.cpp

---

一、创建新节点

        首先创建一个新的节点，用malloc动态开辟一块内存空间，接着将x的值赋给newnode，再将newnode的指针域指向NULL。

SLTNode* BuySListNode(SLTDataType x)
{
	SLTNode* newnode = (SLTNode*)malloc(sizeof(SLTNode));
	newnode->data = x;
	newnode->next = NULL;
	return newnode;
}

二、增加新节点

1.尾插

        尾插要注意的一点是首先要判断链表是否为空，如果为空时，则将链表的newnode赋值给头节点，还有一点要注意的是循环条件一定是当尾节点的指针域为NULL时才跳出循环

void SListPushBack(SLTNode** pphead, SLTDataType x)
{
	SLTNode* newnode = BuySListNode(x);
	if (*pphead == NULL)
		*pphead = newnode;
	else
	{
		//找尾结点指针
		SLTNode* tail = *pphead;
		while (tail->next != NULL)
		{
			tail = tail->next;
		}
		//尾结点，链接新结点
		tail->next = newnode;
	}
}

2.头插

void SListPushFront(SLTNode** pphead, SLTDataType x)
{
	SLTNode* newnode = BuySListNode(x);
	newnode->next = *pphead;
	*pphead = newnode;
}

三、删除节点

1.尾删

        尾删首先要创建两个指针来进行，tail指针位于最后一位而prev指针位于tail指针的前一位。接着要进行判断，当链表为空时，返回空。如果只有头节点，则将头节点内存释放。如果有多个节点，当tail->next = NULL时，将tail释放，并将prev->next指向空。

void SListPopBack(SLTNode** pphead)
{
	if (*pphead == NULL)
		return;
	else if ((*pphead)->next == NULL)
	{
		free(*pphead);
		*pphead = NULL;
	}
	else
	{
		SLTNode* prev = NULL;
		SLTNode* tail = *pphead;
		while (tail->next != NULL)
		{
			prev = tail;
			tail = tail->next;
		}
		free(tail);
		prev->next = NULL;
	}
}

2.头删

void SListPopFront(SLTNode** pphead)
{
	SLTNode* next = (*pphead)->next;
	free(*pphead);
	*pphead = next;
}

四、查找链表中的某个节点

SLTNode* SListFind(SLTNode* phead, SLTDataType x)
{
	SListNode* cur = phead;
	while (cur)
	{
		if (cur->data == x)
			return cur;
		cur = cur->next;
	}
	return NULL;
}

五、在某节点前插入节点

//在pos前面插入x
void SListInsert(SLTNode** pphead, SLTNode* pos, SLTDataType x)
{
	if (pos == *pphead)
		SListPushFront(pphead, x);
	else
	{
		SLTNode* newnode = BuySListNode(x);
		SLTNode* prev = *pphead;
		while (prev->next != NULL)
			prev = prev->next;
		prev->next = newnode;
		newnode->next = pos;
	}
}

六、删除某节点

//删除pos位置的值
void SListErase(SLTNode** pphead, SLTNode* pos)
{
	if (pos == *pphead)
		SListPopFront(pphead);
	else
	{
		SLTNode* prev = *pphead;
		while (prev->next != NULL)
			prev = prev->next;
		prev->next = pos->next;
		free(pos);
	}
}

七、全部代码段

1.test.h

#pragma once
#define _CRT_SECURE_NO_WARNINGS 1
#include
#include

typedef int SLTDataType;
struct SListNode
{
	SLTDataType data;
	struct SListNode* next;
};
typedef struct SListNode SLTNode;

//不会改变链表的头指针，传一级指针
void SListPrint(SLTNode* phead);

//可能改变链表的头指针，传二级指针
void SListPushBack(SLTNode** pphead, SLTDataType x);//尾插
void SListPushFront(SLTNode** pphead, SLTDataType x);//头插
void SListPopFront(SLTNode** pphead);
void SListPopBack(SLTNode** pphead);

SLTNode* SListFind(SLTNode* node, SLTDataType x);
//在pos前面查个x
void SListInsert(SLTNode** pphead, SLTNode* pos, SLTDataType x);
//删除pos位置的值
void SListErase(SLTNode** pphead, SLTNode* pos);

2.SList.cpp

#include"test.h"

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

SLTNode* BuySListNode(SLTDataType x)
{
	SLTNode* newnode = (SLTNode*)malloc(sizeof(SLTNode));
	newnode->data = x;
	newnode->next = NULL;
	return newnode;
}

void SListPushBack(SLTNode** pphead, SLTDataType x)
{
	SLTNode* newnode = BuySListNode(x);
	if (*pphead == NULL)
		*pphead = newnode;
	else
	{
		//找尾结点指针
		SLTNode* tail = *pphead;
		while (tail->next != NULL)
		{
			tail = tail->next;
		}
		//尾结点，链接新结点
		tail->next = newnode;
	}
}

void SListPushFront(SLTNode** pphead, SLTDataType x)
{
	SLTNode* newnode = BuySListNode(x);
	newnode->next = *pphead;
	*pphead = newnode;
}

void SListPopFront(SLTNode** pphead)
{
	SLTNode* next = (*pphead)->next;
	free(*pphead);
	*pphead = next;
}

void SListPopBack(SLTNode** pphead)
{
	if (*pphead == NULL)
		return;
	else if ((*pphead)->next == NULL)
	{
		free(*pphead);
		*pphead = NULL;
	}
	else
	{
		SLTNode* prev = NULL;
		SLTNode* tail = *pphead;
		while (tail->next != NULL)
		{
			prev = tail;
			tail = tail->next;
		}
		free(tail);
		prev->next = NULL;
	}
}

SLTNode* SListFind(SLTNode* phead, SLTDataType x)
{
	SListNode* cur = phead;
	while (cur)
	{
		if (cur->data == x)
			return cur;
		cur = cur->next;
	}
	return NULL;
}

//在pos前面插入x
void SListInsert(SLTNode** pphead, SLTNode* pos, SLTDataType x)
{
	if (pos == *pphead)
		SListPushFront(pphead, x);
	else
	{
		SLTNode* newnode = BuySListNode(x);
		SLTNode* prev = *pphead;
		while (prev->next != NULL)
			prev = prev->next;
		prev->next = newnode;
		newnode->next = pos;
	}
}

//删除pos位置的值
void SListErase(SLTNode** pphead, SLTNode* pos)
{
	if (pos == *pphead)
		SListPopFront(pphead);
	else
	{
		SLTNode* prev = *pphead;
		while (prev->next != NULL)
			prev = prev->next;
		prev->next = pos->next;
		free(pos);
	}
}

3.test.cpp

#include "test.h"

void TestSList1()
{
	SLTNode* plist = NULL;
	SListPushBack(&plist, 1);
	SListPushBack(&plist, 2);
	SListPushBack(&plist, 3);
	SListPushBack(&plist, 4);
	SListPushFront(&plist, 0);
	SListPrint(plist);

	SListPopFront(&plist);
	SListPopFront(&plist);
	SListPopFront(&plist);
	SListPrint(plist);

	SListPopFront(&plist);
	SListPopFront(&plist);
	SListPrint(plist);
}

void TestSList2()
{
	SLTNode* plist = NULL;
	SListPushBack(&plist, 1);
	SListPushBack(&plist, 2);
	SListPushBack(&plist, 3);
	SListPushBack(&plist, 4);
	SListPrint(plist);

	SListPopBack(&plist);
	SListPopBack(&plist);
	SListPopBack(&plist);
	SListPopBack(&plist);
	SListPopBack(&plist);
	SListPrint(plist);
}

void TestSList3()
{
	SLTNode* plist = NULL;
	SListPushBack(&plist, 1);
	SListPushBack(&plist, 2);
	SListPushBack(&plist, 3);
	SListPushBack(&plist, 4);
	SListPrint(plist);

	// 想在3的前面插入一个30
	SLTNode* pos = SListFind(plist, 1);
	if (pos)
	{
		SListInsert(&plist, pos, 10);
	}
	SListPrint(plist);

	pos = SListFind(plist, 3);
	if (pos)
	{
		SListInsert(&plist, pos, 30);
	}
	SListPrint(plist);
}

void TestSList4()
{
	SLTNode* plist = NULL;
	SListPushBack(&plist, 1);
	SListPushBack(&plist, 2);
	SListPushBack(&plist, 3);
	SListPushBack(&plist, 4);
	SListPrint(plist);

	SLTNode* pos = SListFind(plist, 1);
	if (pos)
	{
		SListErase(&plist, pos);
	}
	SListPrint(plist);

	pos = SListFind(plist, 4);
	if (pos)
	{
		SListErase(&plist, pos);
	}
	SListPrint(plist);

	pos = SListFind(plist, 3);
	if (pos)
	{
		SListErase(&plist, pos);
	}
	SListPrint(plist);

	pos = SListFind(plist, 2);
	if (pos)
	{
		SListErase(&plist, pos);
	}
	SListPrint(plist);
}


int main()
{
	TestSList4();

	return 0;
}