Thread: Linked List Question

Hi There, this is my code

Code:

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

struct node
  {
	string data;     
         node *nxt;
  };

node *start_ptr = NULL;
node *current; 

void add_node_at_end()
{
	node *temp, *temp2;   

    
    temp = new node;
    cout << "Please enter any data: ";
    cin >> temp->data;
    temp->nxt = NULL;

    if (start_ptr == NULL)
	{
		start_ptr = temp;
		current = start_ptr;		
          }

    else
    {
		temp2 = start_ptr;
       
		while (temp2->nxt != NULL) 
        {
			temp2 = temp2->nxt;		
        }
        temp2->nxt = temp;
     }
	
}

void display_list()
{
	node *temp;
    temp = start_ptr;
    cout << endl;
    if (temp == NULL)
       cout << "The list is empty!" << endl;
    else
	{
		while (temp != NULL)
		{
			// Display details for what temp points to
             cout << "Data : "<<temp->data;
			 cout << endl;
			 current = current->nxt;
			 temp = temp->nxt;
		}
		cout << "<- Current node"<<"\n";
		cout << "End of list!" << endl;
	}
}

void main()
{
	int i;
	for (i=0; i<5; i++)
		add_node_at_end();

	display_list();
}

my friend add these following lines into my code:

Code:

temp2 = start_ptr;
       
		while (temp2->nxt != NULL) 
        {
			temp2 = temp2->nxt;		
        }
        temp2->nxt = temp;

What actually will the code above do ??

The code in question is adding a new node to the end of the linked list. First have to find the last node, then set the nxt pointer of the last node to point to the new node. And don't forget to set the nxt pointer of the new node to NULL (or 0) so that the next time that code is executed it will indicate the last node in the list.

Originally Posted by Magos

Seriously, give me one good reason why "next" should be shortened...

Not as much typing or thinking

Originally Posted by Magos

Get the last node?


Seriously, give me one good reason why "next" should be shortened...

lol

I still don't see why you would use a linked list rather than an array (linked lists seem like such a pain in the ass..)

well said. Even though you might not see it directly in many applications these days they're there in the background everywhere empowering the more advanced APIs you're programming to.

Originally Posted by Ancient Dragon

The code in question is adding a new node to the end of the linked list. First have to find the last node, then set the nxt pointer of the last node to point to the new node. And don't forget to set the nxt pointer of the new node to NULL (or 0) so that the next time that code is executed it will indicate the last node in the list.

Thx for the answer. I get it now.

Originally Posted by Magos

Seriously, give me one good reason why "next" should be shortened...

Since this is only for testing only, i didn't really put my attention into the naming .

Originally Posted by SlyMaelstrom

I still don't get why you'd use an array over any of the many, many, many standard data structures in C++...

I don't have any other choice since i'm a student and i don't know any data structures beside stack and linked list. furthermore i have to use linked list to do expression evaluation for my assigment . any good advice for me

Originally Posted by SlyMaelstrom

...and as far as modern programming goes, linked lists are simply not used anymore. They're outdated.

Oh so, that's why it says "Liberally stupid" under your name! Makes perfect sense now.