Thread: Chaining Hash Tables (in C)

>The problem is i don't noe where to put the headPtr for each array element
Something like this I would imagine:

Code:

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

struct node *table[SIZE];

>Thanks, but I still can't pictue it
A chained hash table is nothing more than an array of linked lists. Any simpler and you have either an array or a linked list.

>could you maybe expand slightly on it
I already have here.

>and maybe do it in my coding type of styling
That I won't do. Learning to read read code is just as important as learning to write it.

You're making this way too complicated. Just make an array of linked lists. Hash to see what bucket to drop it in, put it in that list.

Code:

struct node *ptr; /* one list */
struct node *array[ SIZE ]; /* many lists */

Of course I very very rarely typedef, because they almost never improve readability. The only exception I've ever found is when dealing with function pointers.


Quzah.

if i declare it outside, just as typedef struct abcPtr array[20], it works...why?

[my reply]: in my code, i did #define ARRAY_SIZE without specifying the number...lol...so all works now

Ok, I've got some problems which i can't solve...

Code:

typedef struct abc* abcPtr;

typedef struct def
{
   defPtr next;
   char *fgh;
}

typedef struct abc
{
   defPtr head;
}abcType;



typedef struct overall
{
    abcPtr array[20];
} overallType

i get errors from the code below, or segmentation faults to be specific...
say i've created an instance of overall as 'ov' and i pass the address of it to a function as &ov

Code:

for(i=0; i<20; i++)
{
   ov->array[i]->head = NULL;
   ov->array[i] = NULL;
}

and this error also (chaining off the array)
   newNode->next = ov->array[aNumber]->head;
   ov->array[aNumber]->head = newNode;

Aside from the fact that your code is horribly unreadable because you inisit on typedefing everything...

Code:

for(i=0; i<20; i++)
{
   ov->array[i]->head = NULL;
   ov->array[i] = NULL;
}

"ov" has an array of poitnters. These pointers don't point at any actual instances, so you can't try to access "head". Doing so is why your program crashes.


Quzah.

>i'm not quite sure what you mean. could you reclarify it?
I get the feeling that you're not ready for this assignment yet. You should be brushing up on pointers, not hash tables.