尾部->下一个打印地址，而不是数据循环链表c

Question

我试图把我的循环单链表的两端连在一起。在文件名文件中。txt，包含ABCDEFGHIJKLMNOPQRSTUVWXYZ作为文本，我能够分别打印出头部和尾部，A和Z。然而，我希望Z指向A，但是我的输出是A的地址（见下文）。我在addNode（）中做错了什么？

#include <string.h>
#include <cstdio>
#include <cstdlib>
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <fstream>    // For file input
#include <cassert>    // for assertions
using namespace std;

    FILE *filename = fopen("file.txt", "r"); // Try to open file


struct Node
  {
  char data;
  Node* next;

  } ;

    void addNode( Node * &head, Node * &tail, char input)
      {
      Node *pTemp = new Node;
      pTemp->data = input;

       if( head == NULL)
          {
            head=pTemp;
           tail=pTemp;
               tail->next = head;
          }

      else
          {
          tail->next = pTemp;
                pTemp->next=head;
          }

    tail=pTemp;

      }//end addNode()


    int main()
      {
      assert(filename);
      Node *head=NULL;
       Node *tail=NULL;
      char c =' ';
      int i=0;

      while( fscanf(filename,"%c", &c) != EOF)
        addNode( head,tail, c);



    cout<<endl;
    cout<<"\nHead element is "<<head->data<<endl;
    cout<<"Tail element is "<<tail->data<<endl;
    cout<<"After tail '"<<tail->data<<"' is : "<< tail->next<<endl;

      }

电流输出为：

Head element is A
Tail element is Z
After tail 'Z' is : 0x371168

期望输出为：

Head element is A
Tail element is Z
After tail 'Z' is : A

Answer 1

tail-

cout<<"After tail '"<<tail->data<<"' is : "<< tail->next->data <<endl;

Answer 2

#include <string.h>
#include <cstdio>
#include <cstdlib>
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <fstream>    // For file input
#include <cassert>    // for assertions
using namespace std;

    FILE *filename = fopen("file.txt", "r"); // Try to open file


struct Node
  {
  char data;
  Node* next;

  } ;

    void addNode( Node * &head, Node * &tail, char input)
      {
      Node *pTemp = new Node;
      pTemp->data = input;

       if( head == NULL)
          {
            head=tail =pTemp;
           tail->next=pTemp;

          }

      else
          {
          pTemp->next = tail->next;
          tail->next=pTemp;
          tail = pTemp;

          }


      }//end addNode()


    int main()
      {
      assert(filename);
      Node *head=NULL;
       Node *tail=NULL;
      char c =' ';
      int i=0;

      while( fscanf(filename,"%c", &c) != EOF)
        addNode( head,tail, c);



    cout<<endl;
    cout<<"\nHead element is "<<head->data<<endl;
    cout<<"Tail element is "<<tail->data<<endl;
    cout<<"After tail '"<<tail->data<<"' is : "<< tail->next->data<<endl;

      }

试试这个。

我已经进一步改进和删除所需的代码从你的addNode。

你想设置“尾巴”的原因-

这样不仅可以遍历第一个和最后一个元素。您可以遍历整个链接列表。

如果您错过了此语句，那么您将无法遍历。上一个节点的下一个变量不会与下一个连接。

例子：

Node A
[A  | pointer to self] <- head and tail 
Node B
[A  | pointer to B ] <-head
[B  | pointer to A ] <-tail
Node C
[A  | pointer to B ] <-head
[B  | pointer to C ]  
[C  | pointer to A ]   <-tail

Node D
[A  | pointer to B ] <-head
[B  | pointer to C ]  
[C  | pointer to D ]    
[C  | pointer to A ]   <-tail