I have been working on the Speller assignment in pset5, and when I run the check50 command, everything seems to be fine.
:) dictionary.c exists
:) speller compiles
:) handles most basic words properly
:) handles min length (1-char) words
:) handles max length (45-char) words
:) handles words with apostrophes properly
:) spell-checking is case-insensitive
:) handles substrings properly
:) program is free of memory errors

But when I start testing the program myself by running "./speller texts/lalaland.txt " This happens

ps5/speller/ $ ./speller texts/lalaland.txt
Segmentation fault (core dumped)

Here is my code, code anyone help spot what is wrong with this.

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

#include "dictionary.h"

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

// TODO: Choose number of buckets in hash table
const unsigned int N = 676;

// Hash table
node *table[N];

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

// Hashes word to a number
unsigned int hash(const char *word)
{
    // TODO: Improve this hash function
    int a = toupper(word[0]) - 'A';
    int b = toupper(word[1]) - 'A';
    return (a * b);
}
int counter;
// Loads dictionary into memory, returning true if successful, else false
bool load(const char *dictionary)
{
    //Open the file and check if it actually exists
    FILE *file = fopen(dictionary, "r");
    if (file == NULL)
    {
        printf("Unable to open file\n");
        return false;
    }
    for (int i = 0; i < N; i  )
        {
            table [i] = malloc(sizeof(node));
            table [i]-> next = NULL;
            for (int u = 0; u < 48 ; u  )
            {
                table [i]-> word[u] = '0';
            }

        }
    char buffer[LENGTH   1];
    //Read all the individual strings from the file
    while (fscanf(file, "%s", buffer) != EOF)
    {
        //Create nodes and copy the words into them
        node *current_node = malloc(sizeof(node));
        if (current_node == NULL)
        {
            return false;
        }
        strcpy(current_node -> word, buffer);
        int hashnumber = hash(buffer);
        node *pointer = table[hashnumber];
        if (pointer == NULL)
        {
            table[hashnumber] = current_node;
            counter  ;
        }
        else
        {
            current_node -> next = table[hashnumber];
            table[hashnumber] = current_node;
            counter  ;
        }
    }
    fclose(file);
    return true;
}

// Returns number of words in dictionary if loaded, else 0 if not yet loaded
unsigned int size(void)
{
    return counter;
}

// Unloads dictionary from memory, returning true if successful, else false
bool unload(void)
{
    for (int i = 0; i < 676; i  )
    {
        node *current = table[i];
        while (current != NULL)
        {
            node *temp = current;
            current = current -> next;
            free(temp);
        }
    }
    return true;
}

CodePudding user response：

Try this:

    node *current_node = malloc(sizeof(node));
    if (current_node == NULL)
    {
        return false;
    }
    current_node->next = NULL; // Missing, and presumed NULL..
    strcpy(current_node->word, buffer);

CodePudding user response：

It seemed like once I initialized the variable as NULL and made changes to the hash function. I checked through the other files and it worked now. Thanks!