复制单链表成为新的链表，然后return the number of items in the new list

关于单链表的知识点，小编就不在这里介绍了，那么就直接上代码吧！

//This is the list.h file#include<iostream>#include<cctype>#include<cstring>using namespace std;struct node{    int data;    node * next;};class list{    public:        //These functions already supplied        list();  //Supplied        ~list(); //Supplied        void build(); //Supplied        void display(); //Supplied        //Copy the contents of a linear linked list and make a new linear linked list        //Return the number of items in the new list        int copy_list(list & to_copy);    private:        //Copy the contents of a linear linked list and make a new linked list        //Return the number of items in the new list        int copy_list(node *& new_head,node*& new_tail, node * head);        node * head;        node * tail;};

因为建立链表需要用到tail指针，那么在函数的prototype里就得传入新的tail指针来指向新的链表

下面是如何实现这两个函数的代码展示：

//This is the list.cpp file#include "file.h"int list::copy_list(list & to_copy){    return copy_list(to_copy.head,to_copy.tail,head);}int list::copy_list(node *& new_head, node *& new_tail, node * head){    if(!head)    {        new_head = NULL;        return 0;    }    new_head = new node;    new_head->data = head->data;    new_tail = new_head;    return new_tail->data + copy_list(new_head->next,new_tail,head->next);}

下面是展示如何在主函数里调用函数：

//This is the main.cpp#include "list.h"int main(){    //This is the original list object    list object;    object.build();  //Builds a LLL    object.display(); //displays the LLL    //This declares a new object    list new_list;    //Copy the contents of a linear linked list and make a new linear linked list    //Return the number of items in the new list    int result = object.copy_list(new_list);    cout<<"The result is: "<<result<<endl;    new_list.display();    return 0;}

下面就展示结果：