单链表—练习

#ifndef _NODE_H_
#define _NODE_H_

typedef struct _node{
	int data;
	struct _node *next; //next是一个Node型的指针。 
}Node;

void add(Node**, int);
void show(Node*);
void find(Node*, int);
void deleteNode(Node**, int);
void destroyList(Node*);

#endif

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</pre><pre code_snippet_id="463884" snippet_file_name="blog_20140904_1_885337" name="code" class="cpp">#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include "linkedlist.h"

using namespace std;

//typedef struct node_{
//	int data;
//	struct node_ *next;
//}Node;

int main(int argc, char** argv) {
	int num;
	
	Node* head = NULL; //head 是一个Node型的指针， 起初指向NULL. 
	//作用类似于链表的初始化； 
	do{
		scanf("%d", &num);
		if(num != -1) 
		{
			add(&head, num);//只有传入head的指针，才能对head进行修改。
			//head本身就是指针了，所以我们传入一个指针的指针； 		
		}	

	}while (num != -1);
	
	show (head);
	cout << "Please input the data you want to find: " << endl;
	int number;
	cin >> number;
	find (head, number);
	cout << "Please input the data you want to delete: " << endl;
	int number1;
	cin >> number1;
	deleteNode(&head, number1);
	show(head);
	destroyList(head);
	cout << "after the free of the whole list, the list now is: "
	show(head);
	return 0;
}
void add(Node** pHead, int num)//pHead是head的指针。传入head, 此时*pHead就是head； 
{
/***********************新创建一个Node*************************/
		Node* p = (Node*)malloc(sizeof(Node));//p是一个Node指针，
		//p指向一片新开辟的空间，该空间是Node大小. 
		p->data = num;
		p->next = NULL;//因为是最新开辟的一个Node，所以将该Node放到链表的末尾。
		
/*********************找到最后的那个Node***************************/
		Node* last = *pHead;//从链表头开始遍历;
		if (last != NULL)//如果head不是NULL，说明链表非空的。那么就从头找到链表的尾巴。 
		{
			while(last->next)
			{
				last = last->next;
			}
/****************把新建立的Node链接到链表的尾巴上*********************/
			last->next = p; //next也是一个Node型的指针。					
		}
/****************如果链表还是空的***********************/		
		else {
			*pHead = p;
		}
}
void show(Node* head)
{	
	cout <<"the linked list is: "<<endl;
	for(Node *p = head; p; p = p->next)
		cout << p->data << " ";	
	cout << endl;	
}
void find(Node *head, int number)
{
	int flag = 0;
	for (Node *p = head; p; p = p->next)
	{
		if (p->data == number)
		{
			flag = 1;
			cout << "we've found the number "<< number << endl;
		}
	}
	if (flag == 0)
	cout << " we cannot find the number " << number << endl;
}

void deleteNode(Node** pHead, int number)
//我们有对head进行修改，需要传入head的指针 
{
	int flag = 0;
	Node* previous;
	Node* p;
	for (previous = NULL, p = *pHead; p; previous = p, p = p->next)
	{
		if (p->data == number)
		{	
			flag = 1;
			if (previous)//如果previous指针非空的话 
				previous->next = p->next;
			else
				*pHead = p->next;	
		free(p);
		cout << "Deletion is successful" << endl;
		break;
		}
	}
	if (flag == 0)
	cout << "We can't find the number you want to delete." << endl;	
}
void destroyList(Node *head)
{
	Node *p, *q;
	for (p = head; p; p = q)
	{
		q = p->next;
		free(p);
	}
}