Question

我需要获取用户输入字符串并将它们放入用c ++编写的链表中。我已经做到这一点，以便我得到用户输入并将其放入列表的一部分，我的问题是它只将一个保存到列表中。我认为问题是我只在链表中有一个对象并继续覆盖它，据说我已经尝试修复它但无法找到方法。我还必须按照字母顺序组织列表，但一次只能一步。这是我的代码：

#include<iostream>
#include<string>
using namespace std;

struct Node{
    string data;
    Node *next;
};

void addToList(Node *head);
void deleteFromList(Node *head);
void printList(Node *head);

int main(){
    bool quit = false;
    int choice;
    Node *head = new Node;
    head->next = NULL;

    while (!quit){
        cout << "1. add to list" << endl
            << "2. delete from list" << endl
            << "3. print list" << endl
            << "4. quit" << endl;
        cin >> choice;
        switch(choice){
        case 1: addToList(head);
            break;
        case 2: deleteFromList(head);
            break;
        case 3: printList(head);
            break;
        case 4: quit = true;
            break;
        default:
            cout << "That is not a valid input, quitting program";
            quit = true;
        }
    }
}

void addToList(Node *head){
    bool quit = false;
    string temp;
    Node *current = new Node;
    current->next = NULL;

    while (!quit){

        cout << "Enter a word(quit to stop)";
        cin >> temp;

        if (temp == "quit"){
            quit = true;
        }
        else{
            current->data = temp;
            current -> next = current;
        }
    }
    return;
}

void deleteFromList(Node *head){
    string deletion;
    cout << "Which value do you want to delete from the list? ";
    cin >> deletion;

    Node *prev = head;
    Node *current = head->next;

    while (current)
    {
        if (current->data == deletion){
            prev->next = current->next;
            delete current;
            return;
        }
        prev = current;
        current = current->next;
    }
    if (!current){
        cout << "That value is not in the list" << endl;
    }
}

void printList(Node *head){
    if (!head)
    {
        cout << "Nothing is in the list." << endl;
        return;
    }

    Node *current = new Node;
    current->next = head;
    while (current)  
    {
        cout << current->data << endl; 
        current = current->next;  
    }
}

Answer 1

在函数addToList中，即使用户添加多个单词，也只分配一个节点。当用户未输入“退出”时，您需要在循环中分配新节点。以下代码应该是正确的：

void addToList(Node *head){
    bool quit = false;
    string temp;
    Node *current;

    while (!quit){

        cout << "Enter a word(quit to stop)";
        cin >> temp;

        if (temp == "quit"){
            quit = true;
        }
        else{
            // Allocate the new node here:
            current = new Node;
            current->data = temp;

            // the new node is inserted after the empty head
            // because head is an empty node in your implementation:
            current->next = head->next;
            head -> next = current;
        }
    }
    return;
}

在功能printList中，您不需要实例化新节点：

void printList(Node *head){
    // head->next, because the head is an empty node in your implementation,
    // but be carefull, head had to never be NULL in your program,
    // so you should also check if head is NULL.
    if (!head->next)
    {
        cout << "Nothing is in the list." << endl;
        return;
    }

    Node *current;
    // set current to head->next, because the head is empty in your implementation:
    current = head->next;
    while (current)
    {
        cout << current->data << endl;
        current = current->next;
    }
}

Answer 2

您也可以尝试此操作

#include <bits/stdc++.h>
using namespace std;
struct node 
{
  int data;
  node* next;
};
void printlinkedlist(node* node)
{
  int c=0; //taken just for good looking output
  while(node!=NULL)
  {
    if(c>0)
    {
      cout<<"->"<<node->data;
      node = node->next;
    }
    else
    {
      cout<<node->data;
      node = node->next;
      c++;
    }
  }
}
int main() {
  int n;
  cout<<"Enter no. of nodes=";
  cin>>n;
  int num,c=0; //initialized c for setting head with second node..
  node* head = new node; //initialized head node
  node * temp = new node; //initialized temp node 
  cin>>num;
  head->data=num;
  for(int i=2;i<=n;i++)
  {
    if(c==0)
    {
      cin>>num;
      temp->data=num;
      head->next=temp; //head point to second node i.e. temp
      c++;
    }
    else
    {
      cin>>num;
      node * temp1 = new node; //initialize other temp node for every value 
      temp1->data=num;
      temp->next=temp1; //point to temp1 to temp 
      temp=temp1; //set temp as temp1 
    }
  }
  printlinkedlist(head); 
}

Answer 3

您应该编辑addToList 替换：

current->next=current;

使用：

head->next=current;

Brcouse你用指针指责当前的电流。顺便说一下，你的问题是：为什么这段代码不能正确添加数据？希望它有所帮助

来自用户输入的链接列表c ++

3 个答案: