指针仿真链表

使用指针模拟链表数据结构

#include<iostream>
using namespace std;

struct node
{
    int data;
    node *next;
};

node *head = {NULL};

void del_by_data(int del_data)  //从链表头向后查找，找到del_data并删除
{
    node *p= NULL,*pre=NULL;
    p=head;
    while(p!=NULL)
    {
        if(del_data==p->data)
        {
            if(pre!=NULL)
                pre->next=p->next;
            if(p==head)
                head=p->next;
            delete p;
            return ;
        }
        pre=p;
        p=p->next;
    }
    return ;
}

void add_rear(int add_data)   //在链表末尾加入一个元素
{
    if(head!=NULL)
    {
        node *add_point,*tmp_point;
        add_point==new node;
        add_point->data==add_data;
        add_point->next==NULL;
        tmp_point=head;
        while(tmp_point->next!=NULL)
            tmp_point=tmp_point->next;
        tmp_point->next=add_point;
    }
    else
    {
        head= new node;
        head->data=add_data;
        head->next=NULL;
    }
}

void add_front(int add_data)  //在链表前端加入一个元素
{
    if(head!=NULL)
    {
        node *add_point;
        add_point=new node;
        add_point->data=add_data;
        add_point->next=head;
        head=add_point;
    }
    else
    {
        head=new node;
        head->data=add_data;
        head->next=NULL;
    }
}

void output()
{
    node *p;
    p=head;
    while(p!=NULL)
    {
        cout<<p->data<<" ";
        p=p->next;
    }
    cout<<"\n";
}

int main()   //演示链表的操作
{
    int ins,data;
    while(1)
    {
        cout<<"1.Insert a value in front  \n";
        cout<<"2.Insert a value in rear \n";
        cout<<"3.Delete a value \n";
        cout<<"4.Quit \n";
        cin>>ins;
        switch(ins)
        {
        case 1:
            cout<<"Please insert a value:";
            cin>>data;
            add_front(data);
            break;
        case 2:
            cout<<"Please insert a value:";
            cin>>data;
            add_rear(data);
            break;
        case 3:
            cout<<"Please insert a value:";
            cin>>data;
            del_by_data(data);
            return 0;
        }
        output();
    }
    return 0;
}