键盘输入创建链表：先进先出与先进后出

1.先进先出

#include<iostream>
#include<vector>
#include<stdio.h>
#include<stdlib.h>

using namespace std;

struct Linked_list
{
    int num;
    Linked_list *next;
};

int main()
{
    Linked_list *head = NULL;
    Linked_list *m = NULL;
    Linked_list *tail = NULL;
    char a;


    while(1)
    {
        Linked_list *p = new Linked_list;
        cout<<"请输入链表数："<<endl;
        cin>>p->num;
        if(head == NULL)
        {
            head = p;
            tail = head;
            p->next = NULL;
        }
        else
        {
            tail->next = p;
            tail = tail->next;
        }
        cout<<"是否继续输入数字Y/N？"<<endl;
        cin>>a;
        if(a == 'N')
        {
            tail->next = NULL;
            break;
        }    
        else
        {
            continue;
        }
        

    }
   
    cout<<"输出链表中的各个数据:"<<endl;
    m = head;
    while(m != NULL)
    {
        cout<<m->num<<endl;
        m = m->next;
    }
    return 0;
}

要点：在先进先出的情况下，并能用p = p->next;来替代tail = tail->next。因为p总是新建的，它的作用于无法直接作用于头尾链表指针，我们需要的是设计好与头尾链表指针相关的程序。
2. 先进后出

#include<iostream>
#include<vector>
#include<stdio.h>
#include<stdlib.h>

using namespace std;

struct Linked_list
{
    int num;
    Linked_list *next;
};

int main()
{
    Linked_list *head = NULL;
    Linked_list *m = NULL;
    char a;
    

    while(1)
    {
        Linked_list *p = new Linked_list;
        cout<<"请输入链表数："<<endl;
        cin>>p->num;
        if(head == NULL)
        {
            p->next = NULL;
            head = p;
        }
        else
        {
            p->next = head;
            head = p;
        }
        cout<<"是否继续输入数字Y/N？"<<endl;
        cin>>a;
        if(a == 'N')
            break;
        else
        {
            continue;
        }
        

    }
    cout<<"输出链表中的各个数据:"<<endl;
    m = head;
    while(m != NULL)
    {
        cout<<m->num<<endl;
        m = m->next;
    }
    return 0;
}