PSet 5

Dictionary.c

/**
 * dictionary.c
 *
 * Computer Science 50
 * Problem Set 5
 *
 * Implements a dictionary's functionality.
 */

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

#include "dictionary.h"

//To store the number of words in the dictionary
static int count = 0;
 // Definition of a word
typedef struct Node
    {
        char word[LENGTH + 1];
        struct Node *next;
    }
node;
node *head;
node *hashtable[500];

//Function for hashing
     int hash_func(char *word)
        {
            return (tolower(word[0]) - 'a');
        }
/**
 * Returns true if word is in dictionary else false.
 */
bool check(const char* word)
{
    for(int i = 0,j = 0,n = strlen(word);i < n;i++,j++)
        {
          //Checking for only alphabets and apostrophes
          if(isalpha(word[i]) || word[i] == '\"')
            {
              if(strcmp(hashtable[j]->word, word)==0)
                {
                  return true;
                }
             }
         }
    return false;
}    

/**
 * Loads dictionary into memory.  Returns true if successful else false.
 */
bool load(const char* dictionary)
{   
    FILE * dic = fopen(dictionary,"r");
    if(dic == NULL)
        {
            printf("File not found\n");
            return false;
        }
    //Check if we have reached the end of file
    if(!feof(dic))
    {
      node* new_node = malloc(sizeof(node));
      fscanf(dic,"%s",new_node->word);
      int index = hash_func(new_node->word);
      //Check if the index returned is free
      if(hashtable[index] == NULL)
        {
            hashtable[index] = new_node;
            new_node->next = NULL;
        }
        //If location is not vacant, traverse the remaining hashtable to find a vacant location to store the word
        else
            {
                node* trav = hashtable[index];
                while(trav != NULL)
                    {
                        trav = trav->next;
                    }
                trav = new_node;
            }
        count++;   
            
    }
 fclose(dic);
 return true;
}

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

/**
 * Unloads dictionary from memory.  Returns true if successful else false.
 */
bool unload(void)
{
    node* trav = head;
    while(trav != NULL)
        {
            node* temp = trav;
            trav = trav->next;
            free(temp);
        }
    return true;    
}