PSET 5 Load and Hash seg fault

Question

I've update the code somewhat. Mostly fixing my hash function so it will run properly with non alphabetical words.

Three hours into this though and I still can't seem to figure it out.

I know now it halts at this line.

node->next = table[index]; //This line specifically according to the debugger

unsigned int hash(const char *word)
{
    int sum;
    int p;
    for(int i = 0; i < strlen(word); i++) {
        if(isalpha(word[i]) == 0)
        {
            p = 96;
        }

        else 
            p = tolower(word[i]);

        int cnv = p - 96;
        sum = sum + cnv;
        p = 0;
    }
    return sum;
}



// Loads dictionary into memory, returning true if successful else false
bool load(const char *dictionary)
{
    // TODO
    // Open Dictionary File
    FILE *dict = fopen(dictionary, "r");
    if (dict == NULL)
    {
        printf("Could not open file");
        return false;
    }
    
    char buffer[LENGTH+1];
    
    while(fscanf(dict, "%s" , buffer) != EOF) {

        // Malloc for a new node
        node *node = malloc(sizeof(node));

        if(node == NULL) {
            printf("Could not allocate memory for *node");
            return false;
        }
                    
        sizeD++;
        // Copy the contents of buffer into the new node
        strcpy(node->word, buffer);

        // Get the hash value of the node
        int index = hash(node->word);

        // If the pointer at that index is empty, point it to the node (if its the first of its kind)      
        node->next = table[index];
        table[index] = node;              
    }

    fclose(dict);
    return true;
}

And since you are already here. For node->next = table[index]; why isn't it written as node->next = table[index]->next. Shouldn't I copy the value of a pointer? I don't understand how this is supposed to work if it's just pointing to the table[index] rather than what the table[index] is pointing at.

Any other issues you see with the code please feel free to bring up as I am trying to learn what else I am doing wrong.

Thank you!

Answer 1

Actually, your load() function is absolutely fine. The problem is your hash() unction. Your not normalising (%) the hash value by table length. which is why node->next = table[index]results in seg fault, because index > table length