PSET5 Speller everything works but then I catch all the words as misspelled

Question

Basically when I run the test with texts/lalaland.txt and compare to the staff's key, they have something like 955 misspelled words and I have all but 5 misspelled. I tried to but a "tolower" in my hash code, and still didn't work

// Implements a dictionary's functionality

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <ctype.h>

#include "dictionary.h"

// Represents a node in a hash table
typedef struct node
{
    char word[LENGTH + 1];
    struct node *next;
}
node;

// Number of buckets in hash table
const unsigned int N = 65366;

// Hash table
node *table[N];

int word_number = 0;

// Returns true if word is in dictionary else false
bool check(const char *word)
{
    int hashed = hash(word);
    node *cursor = table[hashed];
    
    while (cursor != NULL)
    {
        if (strcasecmp(cursor->word, word) == 0)
        {
            return true;
        }
        cursor = cursor->next;
    }
    return false;
}

// Hashes word to a number
// hash function by yangrq1018 on GitHub (Rocky Yang)
unsigned int hash(const char *word)
{
    unsigned int hash = 0;
    char* lower = NULL;
    
    for (int j = 0; j < strlen(word); j++)
    {
        lower[j] = tolower(word[j]);
    }
    
    for (int i = 0, h = strlen(word); i < h; i++)
    {
        hash = (hash << 2) ^ lower[i];
    }
    return hash % N;
}

// Loads dictionary into memory, returning true if successful else false
bool load(const char *dictionary)
{
    FILE *text = fopen(dictionary, "r");
    if (ferror(text))
    {
        return false;
    }
    if (text == NULL)
    {
        return false;
    }
    
    char word_list[LENGTH + 1];
    while (fscanf(text, "%s", word_list) != EOF)
    {
        word_number++;
        //printf("%i\n", word_number);
        
        node *n = malloc(sizeof(node));
        if (n == NULL)
        {
            return false;
        }

        strcpy(n->word, word_list);
        
        unsigned int bucket = hash(dictionary);
        if (table[bucket] == NULL)
        {
            table[bucket] = n;
            n->next = NULL;
        }
        else
        {
            n->next = table[bucket];
            table[bucket] = n;
        }
    }
    fclose(text);
    return true;
}

// Returns number of words in dictionary if loaded else 0 if not yet loaded
unsigned int size(void)
{
    if (word_number != -1)
    {
        printf("World Count: %i\n", word_number);
        return word_number;
    }
    else
    {
        return 0;
    }
}

// Unloads dictionary from memory, returning true if successful else false
bool unload(void)
{
    node* tmp = NULL;
    node* pointer = NULL;
    
    for (int i = 0; i < N; i++)
    {
        pointer = table[i];
        while (pointer != NULL)
        {
            tmp = pointer;
            pointer = pointer->next;
            free(tmp);
        }
    }
    free(pointer);
    return true;
}

Answer 1

When you added the code for tolower() into the hash function, it introduced a seg fault. The tolower code is needed, but you need to fix it. Hint: where is space allocated for lower[]?

Next question. In load,

    unsigned int bucket = hash(dictionary);

Wouldn't it be more useful to get the hash of the word instead of the filename of the dictionary file??? ;-)

Just out of curiosity, did you run this under debug50, or any debugger?

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