Cannot clear segmentation fault in load pset5

Question

I use a simple (or so I thought) code to load the dictionary, no optimization. Yet I keep getting into segmentation fault. In this example I use the small dictionary, which only has 2 words. In my code, I would have expected my while() loop to run 2 times. Using gdb, however, I seem to have found that the while() loop always run 3 times instead. Thus, the 3rd time it runs, it seems to load up N->word with Null value, then messes up the value variable to a negative value (value becomes (0 - 97)%26, which then messes up the next 2 pointer assignment sentences. That's my understanding, but I'm not sure how to fix it. Help appreciated.

bool load(const char* dictionary)
{
    // Initializes a hash table made up of pointers to singly linked lists
    for (int i = 0; i < n; i++)
    {
        table[i] = malloc(sizeof(node));
        table[i] -> next = NULL;
    }
    //set up to load dictionary
    FILE *ptr = fopen(dictionary,"r");

    //The hash function simply modulus the first letter and put the words   into linked lists corresponding to 26 buckets
    while (fgetc(ptr) != EOF)
    {
        node *N = malloc(sizeof(node));
        fscanf(ptr,"%s",N->word);
        int value = (N->word[0] - 97) % n;
        //insert the new node into the beginning of the linked list ie. linked list kinda sorted backwards!
        N->next = table[value]->next;
        table[value]->next = N;
    }

    return true;
}

Answer 1

There is one mistake here:

while (fgetc(ptr) != EOF)

doesn't just work as a condition, but it does read a char and moves on, so next time you read a string it's gonna miss the first char of the word because it was read by fgetc(). Fix that and report back. I would suggest you use the fscanf() in your loop condition instead (but then remove it from inside the body of the loop).

Also, you would be better of declaring table as node* table[n], so that the members of table are just pointers to nodes, not nodes themselves. In fact, you never use the nodes created in your table. You just use their next attribute, which is itself a pointer to node.

Maybe you are trying to read the word stored in table[i] somewhere in your code, but since there is nothing there you get the segfault.