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CS50 Pset5 Speller: dictionary.c
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| // Implements a dictionary's functionality | |
| #include <stdbool.h> | |
| #include <stdio.h> | |
| #include <stdlib.h> //for malloc! | |
| #include <ctype.h> | |
| #include <string.h> | |
| #include "dictionary.h" | |
| // defining global variables | |
| node* root; | |
| node* temp; | |
| int dictsize = 0; | |
| // Returns true if word is in dictionary else false; check must be case-insensitive, word CANNOT be modified | |
| bool check(const char *word) | |
| { | |
| // TODO | |
| // All words in dictionary are lower-case. If word in dict, return true | |
| temp = root; | |
| //for every char in word to be tested | |
| for (int j = 0, n = strlen(word) + 1; j <= n; j++) | |
| { | |
| int i; | |
| char lowletter = tolower(word[j]); | |
| if (isalpha(lowletter)) //for word[j] = 'f' | |
| i = lowletter - 97; | |
| else if (lowletter == '\'') | |
| i = 26; | |
| //NOT reached end of string, | |
| if (lowletter != '\0') | |
| { | |
| //but gate closed | |
| if (temp->children[i] == NULL) | |
| return false; | |
| //but gate open, i.e part of a word | |
| else | |
| temp = temp->children[i]; | |
| } | |
| else if (lowletter == '\0') | |
| { | |
| if (temp->is_word == true) | |
| return true; | |
| } | |
| } | |
| return false; | |
| } | |
| // Loads dictionary into memory, returning true if successful else false | |
| bool load(const char *dictionary) | |
| { | |
| //create pointer to root/top of the tree, never touch root again, USE CALLOC!! So that you initialise the value of mem allocated to 0, else could be some garbage value | |
| root = calloc(1, sizeof(node)); | |
| temp = root; | |
| int i; | |
| //opening dict | |
| FILE* dict = fopen(dictionary, "r"); | |
| if (dict == NULL) | |
| { | |
| printf("Could not open %s.\n", dictionary); | |
| return 1; | |
| } | |
| //for every char in each word in dict, keep getting chars until reach the end of dict file | |
| //check value at children[i], if NULL, malloc a new node and have children[i] point to this new node | |
| for (int c = fgetc(dict); c != EOF; c = fgetc(dict)) | |
| { | |
| if (isalpha(c)) | |
| { | |
| i = tolower(c) - 97; | |
| if (temp->children[i] == NULL) | |
| { | |
| temp->children[i] = calloc(1, sizeof(node)); | |
| //have children[i] point to this new node | |
| temp = temp->children[i]; | |
| } | |
| else if (temp->children[i] != NULL) | |
| { | |
| temp = temp->children[i]; | |
| } | |
| } | |
| else if (c == '\'') | |
| { | |
| i = 26; | |
| if (temp->children[i] == NULL) | |
| { | |
| temp->children[i] = calloc(1, sizeof(node)); | |
| temp = temp->children[i]; | |
| } | |
| else if (temp->children[i] != NULL) | |
| { | |
| temp = temp->children[i]; | |
| } | |
| } | |
| //if done with last char in word | |
| if (c == '\n') | |
| { | |
| temp->is_word = true; | |
| dictsize++; | |
| // RESET temp back to root | |
| temp = root; | |
| } | |
| } | |
| //RMB to close dict after done using it | |
| fclose(dict); | |
| return true; | |
| } | |
| // Returns number of words in dictionary if loaded else 0 if not yet loaded | |
| unsigned int size(void) | |
| { | |
| return dictsize; | |
| } | |
| // Unloads/Frees dictionary from memory, returning true if successful else false | |
| void unloadnode(node* cursor); | |
| bool unload(void) | |
| { | |
| // use free, unload from bottom to top, RECURSION (base case, normal case) | |
| // travel to lowest possible node, free all pointers in children then the node itself | |
| unloadnode(root); | |
| return true; | |
| } | |
| void unloadnode(node* cursor) | |
| { | |
| //free children, then free node itself | |
| for (int i = 0; i < 27; i++) | |
| if (cursor->children[i] != NULL) | |
| { | |
| unloadnode(cursor->children[i]); | |
| } | |
| free(cursor); | |
| } |
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