cs50 Problem Set 5 - Speller Solution

dictionary.c

// Implements a dictionary's functionality

#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <strings.h>
#include <stdint.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 = 65536;

// Hash table
node *table[N];

// count read words
int total_words = 0;

// Returns true if word is in dictionary else false
bool check(const char *word)
{
    // make word lower case for hash function
    int len = strlen(word);
    char lword[len + 1];
    for (int i = 0; i < len; i++)
    {
        lword[i] = tolower(word[i]);
    }
    lword[len] = '\0';

    int index = hash(lword);
    node *cursor = table[index];
    while (cursor != NULL)
    {
        if (strcasecmp(cursor->word, word) != 0)
        {
            cursor = cursor->next;
        }
        else
        {
            return true;
        }

    }
    return false;
}

// Hashes word to a number
unsigned int hash(const char *word)
{
    unsigned int hash = 0;
    for (int i = 0, n = strlen(word); i < n; i++)
        hash = (hash << 2) ^ word[i];
    return hash % N;
}

// Loads dictionary into memory, returning true if successful else false
bool load(const char *dictionary)
{
    FILE *file = fopen(dictionary, "r");
    if(!file){
        return false;
    }
    char buffer[LENGTH + 1];

    while(fscanf(file, "%s", buffer) != EOF)
    {
        node *n = malloc(sizeof(node));

        strcpy(n->word, buffer);

        unsigned int index = hash(buffer);

        if(table[index] != NULL)
        {
           n->next = table[index];
        }else {
            n->next = NULL;
        }

        table[index] = n;

        total_words++;

    }

    fclose(file);
    return true;
}

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

    return total_words;
}

void destroy(node *root){

    if(root->next != NULL){
        destroy(root->next);
    }
    free(root);

}

// Unloads dictionary from memory, returning true if successful else false
bool unload(void)
{
    for (int i = 0; i < N; i++)
    {
        if(table[i]!= NULL)
        {
            destroy(table[i]);
        }
    }
    return true;
}

Looks good!

Bro,your code too had problems with memory?(the last face stayed so " :( " )