Link List with the Tail pointer.

[noway2]

We are trying to make the linklist work with a tail and a head pointer. I think there is an error @ line 26.

" tail->next = new;"

We are trying to change whatever the tail pointer is pointing next to the new node. It's probably a syntax error.

Thanks for your help.

#include<stdio.h>
#include<string.h>
#include<stdlib.h>


struct node {
    int id;
    struct node* next;
};
/* if it's the first item, pass in HEAD
 * else pass in the TAIL
 */
void addNode(struct node** head, struct node** tail, int id)
{
    struct node* new = malloc(sizeof(struct node* ));
    if(head == NULL)
    {
        new->id = id;
        new->next = NULL;
        *head = new;
        *tail = new;
    }
    else
    {
        new->id = id;
        new->next = NULL;
        tail->next = new;
        *tail = new;
    }




}
void printList(struct node* head)
{
    
    while(head != NULL)
    {
        printf("I M INHERE!!! \n");
        printf("ID %d", head->id);
        head = head->next;


    }


}






int main()
{
    struct node* head;
    struct node* tail;
    head = malloc(sizeof(struct node*));
    tail = malloc(sizeof(struct node*));
    head = NULL;
    tail = head;


    int i;
    for(i = 0; i < 5; i++)
    {
        addNode(&head,&tail, i);


    }
    printList(head);




    return 0;
}

[iMalc]

Delete lines 59 and 60 from main:

    head = malloc(sizeof(struct node*));
    tail = malloc(sizeof(struct node*));

You shouldn't allocate memory and then throw it away like that.

Line 27 (not 26) is wrong because you can't use -> on a double-pointer. First dereference it to get to a single pointer, i.e. (*tail) and then use the arrow.

[Salem]

> if(head == NULL)
Should be
if(*head == NULL)

> tail->next = new;
Should be
(*tail)->next = new;

And the two malloc calls in main are redundant.

[noway2]

Thanks sooooo much!
It makes sense..
I forgot about the
head in ___ if(head == NULL);
should be a head pointer.. for that I need to dereference to get the head pointer...


Thanks agains for the help.
Now I am going to implement delete fcn or dequeue()
and an insert sort fcn.