Thread: Implementing a linked list, some problems

The problem is elsewhere, your code is fine (though use of references would save you from double pointer hell):

Code:

class Stack {
public:
  Stack ( int init, Stack *link )
    : data ( init )
    , next ( link )
  {}
public:
  int data;
  Stack *next;
};

void Push ( Stack *&top, Stack *new_item )
{
  new_item->next = top;
  top = new_item;
}

void Pop ( Stack *&top, Stack *&old_item )
{
  old_item = top;
  top = top->next;
}

#include <iostream>

int main()
{
  Stack *mystack = 0;
  Stack *save;

  for ( int i = 0; i < 10; i++ )
    Push ( mystack, new Stack ( i, mystack ) );
  while ( mystack != NULL ) {
    Pop ( mystack, save );
    std::cout<< save->data <<std::endl;
    delete save;
  }
}

from what you posted prelude, my problem is here:

Code:

...
 
while(Current->next != NULL)
{
...
}

...

it should be :

Code:

while(Current != NULL)
{
...
}

EDIT: hmmm.... that wasnt the problem.

here is my code btw.

Code:

#include <stdio.h>
#include <iostream>
using namespace std;

struct node
{
  int data;
  node *next;
};

void Push(node** head,node* new_node)
{
  new_node->next = *head;
  *head = new_node;
};

void display(node* head)
{
  node *current;
  current = head;

  while (current != NULL)
  {

    cout << current->data << endl;
    current = current->next;
  }
};

int main()
{
  node* head = new node;
  node* item = new node;

  head->next= NULL;

  item->data = 5;
   Push(&head,item);
   item->data = 8;
   Push(&head,item);

display(head);
  return 0;
};

Remember that each new node is distinct from the others. What you were doing is using a single memory block (assigned to item) as all of the new nodes. The end result is some messed up links, but not a linked list. Try this instead:

Code:

void display(node* head)
{
  node *current;
  current = head;

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

int main()
{
  node* head = new node;
  node* item = new node;

  head->next= NULL;

  item->data = 5;
  Push(&head,item);
  item = new node;
  item->data = 8;
  Push(&head,item);

  display(head);
  return 0;
};

I changed your display function back to the way it was because you appear to want head as a dummy node instead of a valid data node. My changes are highlighted red.

>I heard that there are actually quadruple linked lists
You can have as many links as you want. I've written a data structure that has next, prev, up, down, in, and out to make up the linked equivalent of a three dimensional array.

>I was wondering if you had heard of them.
Unfortunately, I've had the bad luck of working with them. Avoid such structures whenever you can, they're a nightmare to maintain.