CS50-pset5 dictionary.c

dictionary.c

/**
 * Implements a dictionary's functionality.
 */

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

#include "dictionary.h"

// Root Node
node *root = NULL;

// Tracks No. of words in dictionary
int words = 0;

node *createnode(void)
{
	// allocate memory for new node
	node* new_node = (node*) malloc(sizeof(node));
	
	new_node->is_word = false;
	
	// set all pointers to NULL
	for (int i = 0; i < 27; i++)
		new_node->children[i] = NULL;
		
	return new_node;
}


/**
 * Returns true if word is in dictionary else false.
 */
bool check(const char *word)
{
    node *trav = root;
    int c;
    int i = 0;
    
    do
    {
        // Reads characters of words one by one
        c = word[i];
        
        // change to lowercase
        if(c <= 90 && c >= 65) 
        {
            c += 32;
        }
        
        // Only allows alphabets or apostrophe
        if((c >= 97 && c <= 122) || (c == '\''))
        {
            if(trav->children[c - 96] == NULL)
            {
                return false;
            }
            else
            {
                trav = trav->children[c - 96];
            }
        }
        
        i++;
    }while(c != '\0');
    
    return trav->is_word;
}


/**
 * Loads dictionary into memory. Returns true if successful else false.
 */
bool load(const char *dictionary)
{
    // open input file
    FILE *dict = fopen(dictionary, "r");
    
    if(dict == NULL)
    {
        printf("File doesn't exist.\n");
        return false;
    }

    char c;
    
    // memory aloocation to root node
    root = createnode();
    
    // Node trav to tranverse through the linked list
    node *trav = root;
    
    do
    {
        c = fgetc(dict);
        if(isalpha(c) || c == '\'')
        {
            // Checks if the node already exists or not
            if(trav->children[c-96] == NULL)
            {
                trav->children[c-96] = createnode();
            }
            trav = trav->children[c-96];
        }
        else if(c == '\n')
        {
            // Sets is_word to true when we reach end of the word
            trav->is_word = true;
            words++;
            trav = root;
        }
    
        
    }while(c != EOF);
    
    fclose(dict);
    return true;
}


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

bool delnode(node *trav)
{
    // calls function delnode on every node in node's children
    for(int i = 0; i < 27; i++)
    {
        if(trav->children[i] != NULL)
        {
            return delnode(trav->children[i]);    
        }
        
    }

    free(trav);
    return true;
}

/**
 * Unloads dictionary from memory. Returns true if successful else false.
 */
bool unload(void)
{
    
    // calls recursive function delnode 
    return delnode(root);
    
}