一個鏈表的反序

listNode.h

#pragma once
#include <stdio.h>

struct node
{
	int i;
	struct node* next;

};
//新增一個鏈表節點
void addListNode(struct node* head, int idata);
//打印鏈表節點
void printListNode(struct node* head);
//反序
struct node* reverseOrderListNode(struct node* head);
//創建一個頭的鏈表節點
struct node* createHeadNode(int idata);

listNode.cpp

#include "listNode.h"
#include "malloc.h"
int addNode(int iData)
{
	return 1;
}


struct node* createHeadNode(int idata)
{
	struct node* head = (struct node*)malloc(sizeof(struct node));
	if (head)
	{
		head->i = idata;
		head->next = NULL;
	}	

	return head;
}
void addListNode(struct node*head, int idata)
{
	struct node* pTemp = head;
	
	while(NULL != pTemp->next)
	{
		pTemp = pTemp->next;
	}
	pTemp->next = (struct node*)malloc(sizeof(struct node));
	pTemp->next->i = idata;
	pTemp->next->next = NULL;
}

void printListNode(struct node*head)
{
	printf("\n");
	struct node* temp = head;
	while (temp)
	{
		printf("%d ", temp->i);
		temp = temp->next;
	}
	printf("\n");
}
//把head的next(p1） 放入head的前面，head=p1,
struct node* reverseOrderListNode(struct node*head)
{
	if (NULL == head)
	{
		return head;
	}
	
	struct node* p2 = head->next;
	head->next = NULL;
	struct node* p1 = head;
	struct node* p3 = NULL;
	while (p2)
	{
		p3 = p2->next;
		p2->next = p1;
		head = p2;
		p1 = p2;
		p2 = p3;
	}
	printf("%d ", head->i);

	return head;
//	printListNode(head);
}

測試的

void testNodeList()
{
    struct node* head = createHeadNode(0);
    addListNode(head, 1);
    addListNode(head, 2);
    addListNode(head, 3);
    addListNode(head, 4);
    printListNode(head);

    head = reverseOrderListNode(head);
    printListNode(head);

}
int main()
{
    
    testNodeList();

}

測試結果：

0 1 2 3 4

4 3 2 1 0

 

容易的錯誤：一個指針的如果可能被改變，那麼在傳入實參的時候一定要注意，

    要麼實參是指針的指針；要麼返回修改的指針

struct node* reverseOrderListNode(struct node*head)