从用户输入创建和打印链表

Creating and printing linked list from user input C++

本文关键字：打印 链表 创建 用户 输入      更新时间：2023-10-16
#include <iostream>
using namespace std;
int main()
{
    struct node
    {
        int data;
        node * next;
    };
    node * head;
    node * n;
    node * temp;
    node * q;
    int number;
    cout << "Enter numbers";
    cin >> number;
        n = new node;
        n->data = number; 
        head = n;
        temp = n; 
    while (cin >> number)
    {
        while (number != -500)
        {
            n = new node;
            n->data = number;
            temp->next = n;
            temp = n;
        }
    }

    while (head != NULL)
    {
        cout << head->data;
        head = head->next; 
    }
}

我不明白为什么这不起作用。该程序创建一个新节点，然后设置用户输入的与该新节点的变量数据相等的任何内容，然后使head和temp指向新节点。然后它获取用户的第二个输入，并将其与-500进行比较，如果结果为真，则创建一个新节点，将第二个输入的数据放入变量data中，然后将第一个节点和第二个节点链接在一起，然后将temp点指向第二个节点。如果第二个while循环的条件为false，则转到第三个循环，这是应该打印列表的地方。

谁将最后一个节点的旁边设置为NULL?

At n =新节点;n->next不是NULL但未定义，在调试版本中通常是0xcccccccc或类似的值，以使其可见，它没有初始化。如果你试图解引用它，你会得到一个访问冲突

while (cin >> number) { // this loop is endless, because you can always read the user input data (unless some exception happen)
    while (number != -500)
    {
        n = new node; // you already have data allocated. no need to allocate it once more
        n->data = number;
        temp->next = n;
        temp = n;
// as was already mentioned: set n->next to NULL
    } }

如果您想在检查数字不是-500之后中断，那么您可以执行以下操作:

   while (cin >> number) {
    if (number != -500) { ...; // do your stuff
     break;
    }
   }

并且，顺便说一下，您有内存泄漏。如果您使用平面C指针，则考虑使用delete运算符来清除内存。为此，您需要知道列表从哪里开始(基本上是头)，并在调用delete node的整个列表中迭代。

也请考虑，这样写是一种糟糕的代码风格:

while (cin>> number)

您也可以尝试这个-下面的代码根据用户输入创建一个链表，printlinkedlist(函数)打印创建的链表。

    #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; //User enters number of nodes he want.
      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); 
    }

#include<iostream>
using namespace std;
class node{
public:
int data;
node* next;
};
// a function to create linked list passing pointer to pinter
void create_list(node**head)
{
int num;//num is the data
    cin>>num ;
  node*new_node=new node();//
  new_node->data=num;
  new_node->next=NULL;
node*temp;
  if(*head==NULL)
 {
      *head=temp=new_node;
  }
  else{
      temp->next=new_node;
      temp=new_node;
  }
  
  }
  void print_list(node* head)
  {
if(head == NULL)
{
    cout<<"empty list"<<endl;
}
node *ptr = NULL;
ptr=head;
cout<<"data in the list: "<<endl;
while(ptr!=0)
{
    
    
        cout<<ptr->data<<endl;
        ptr=ptr->next;
    
   
}
}

int main()
{
int n,i; //
cout<<"enter the number of nodes:"<<endl;
cin>>n;
cout<<"enter data as num:"<<endl;
node* head=NULL; 
for(i=0;i<n;i++)
{
create_list(&head);//passing the address of head
}

print_list(head);
return 0;
}
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