dictionary.c

/****************************************************************************
 * dictionary.c
 *
 * Computer Science 50
 * Problem Set 5
 *
 * Implements a dictionary's functionality.
 ***************************************************************************/
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include "dictionary.h"
#include <ctype.h>
#include <string.h>


#define SIZE 250000

typedef struct node
{
    char word[LENGTH + 1];
    struct node* next;
}
node;

// Make a hash table
node* hashtable[SIZE];
char temp_word[LENGTH + 1];
unsigned int word_ctr = 0;

// this hash function is from delipity on reddit
int hash_d(char* word)
{

    unsigned int hash = 0;
    for (int i = 0, n = strlen(word); i < n; i++)
    {
        hash = (hash << 2) ^ word[i];
    }

    return hash % SIZE;
}
/**
 * Returns true if word is in dictionary else false.
 */
bool check(const char* word)
{
    // TODO
    char new_word[LENGTH + 1];
    for (int i = 0, n = strlen(word); i <= n; i++)
    {
        new_word[i] = word[i];
        new_word[i] = tolower(new_word[i]);
    }

    // determine the correct hash position
    int y = hash_d(new_word);

    // point the cursor to the first item in the list we identified
    node* cursor = hashtable[y];

    // search the linked list
    while (cursor != NULL)
    {
        if (strcmp1(cursor->word,new_word) == 0)
        {
            return true;
        }
        else
        {
            cursor = cursor->next;
        }
    }
    return false;
}


/**
 * Loads dictionary into memory.  Returns true if successful else false.
 */
bool load(const char* dictionary)
{
    // TODO
    // do some prep work
    FILE* inptr = fopen(dictionary,"r");
    if (inptr == NULL)
    {
        printf("Could not open %s.\n",dictionary);
        return 2;
    }

     // while there are words available
    while (fscanf(inptr,"%s\n",temp_word) != EOF)
    {
        node* new_node = malloc(sizeof(node));
        new_node->next = NULL;
        strcpy(new_node->word,temp_word);
        word_ctr++;
        int x = hash_d(new_node->word);
        // get it into that list
        new_node->next = hashtable[x];
        hashtable[x] = new_node;
    }
    // do some cleanup work
    fclose(inptr);
    return true;
 }
/**
 * Returns number of words in dictionary if loaded else 0 if not yet loaded.
 */
unsigned int size(void)
{
    // TODO
    return word_ctr;
}

/**
 * Unloads dictionary from memory.  Returns true if successful else false.
 */
bool unload(void)
{
    // TODO

    for (int i = 0; i < SIZE ; i++)
    {
        node* cursor = hashtable[i];
        while (cursor != NULL)
        {
            node* temp = cursor;
            cursor = cursor->next;
            free(temp);
        }
    }
    return true;
}