c++类的简单实现

#include <iostream>
#include <stdio.h>
using namespace std;

class link_list
{
    private:
        struct node
        {
            int data;
            node *next;
        }*head;
    public:
        link_list()//构造函数
        {
            head = NULL;
        }
        ~link_list()//析构函数
        {
            cout<<"析构函数,释放链表!\n";
            node *tmp ;
            if(head == NULL)
                return ;
            while(head != NULL)
            {
                tmp = head->next;
                delete head;
                head = tmp;
            }
        }

        void insert(int n);//增
        void del(int n);//删
        bool update(int oldn,int newn);//改
        bool seek(int n);//查
        
        void display();

}list;

void link_list::insert(int n)
{
    node *tmp,*p;
    if(head == NULL)
    {
        head = new node;//新建头结点
        head->data = n;
        head->next = NULL;
    }
    else
    {
        tmp = head;
        while(tmp->next != NULL)
            tmp = tmp->next;
        p = new node;
        p->data = n;
        p->next = NULL;
        tmp->next = p;
    }

}


void link_list::display()
{
    node *tmp = head;
    if(head == NULL)
    {
        cout<<"链表为空！\n"<<endl;
        return;
    }
    while(tmp != NULL)
    {
        cout<<tmp->data<<"  ";
        tmp = tmp->next;
    }
}

void link_list::del(int n)
{
    node *tmp = head;
    if(tmp->data == n)//删除第一个元素
    {
        head = tmp->next;
        delete tmp;
        return ;
    }
    node *ptr = tmp->next;
    while(ptr != NULL)//除了第一个元素外的其他元素
    {
        if(ptr->data == n)
        {
            tmp->next = ptr->next;
            delete ptr;
            return ;
        }
        ptr = ptr->next;
        tmp = tmp->next;
    }
    cout<<"没有找到该元素！\n"<<endl;
}


bool link_list::update(int oldn,int newn)
{
    node *tmp = head;
    while(tmp != NULL)
    {
        if(tmp->data == oldn)
        {
            tmp->data = newn;
            return true;
        }
        tmp = tmp->next;
    }
}

bool link_list::seek(int n)
{
    node *tmp = head;
    while(tmp != NULL)
    {
        if(tmp->data == n)
        {
            return true;
        }
        tmp = tmp->next;
    }
}


int main()
{

    link_list list;
    //插入操作
    cout<<"插入元素：\n";
    list.insert(1);
    list.insert(3);
    list.insert(5);
    list.insert(7);
    list.insert(9);
    list.insert(11);
    list.display();
    
    cout<<endl; 
    //删除操作
    cout<<"删除元素："<<endl;
    list.del(1);//删除第一个元素
    list.del(7);//删除中间的元素
    list.del(11);//删除最后一个元素
    list.display();
    
    cout<<endl; 
    //修改操作
    cout<<"修改元素：\n";
    if(list.update(3,4))
        cout<<"修改成功！\n";
    else
        cout<<"修改失败，没有找到该元素\n";
    list.display();

    cout<<endl; 
    //查找操作
    cout<<"查找元素：\n";
    if(list.seek(5))
        cout<<"找到改元素!\n";
    else
        cout<<"没有找到该元素!\n";
    return 0;
}