Bool unload(void) function. is the parameter for it set void because it is taking input of root node from global variable root?

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// Saves popular dog names in a trie

// https://www.dailypaws.com/dogs-puppies/dog-names/common-dog-names

#include <cs50.h>

#include <ctype.h>

#include <stdbool.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define SIZE_OF_ALPHABET 26

#define MAXCHAR 20

typedef struct node

{

    bool is_word;

    struct node *children[SIZE_OF_ALPHABET];

} node;

// Function prototypes

bool check(char *word);

bool unload(void);

void unloader(node *current);

// Root of trie

node *root;

// Buffer to read dog names into

char name[MAXCHAR];

int main(int argc, char *argv[])

{

    // Check for command line args

    if (argc != 2)

    {

        printf(“Usage: ./trie infile\n”);

        return 1;

    }

    // File with names

    FILE *infile = fopen(argv[1], “r”);

    if (!infile)

    {

        printf(“Error opening file!\n”);

        return 1;

    }

    // Allocate root of trie

    root = malloc(sizeof(node));

    if (root == NULL)

    {

        return 1;

    }

    root->is_word = false;

    for (int i = 0; i < SIZE_OF_ALPHABET; i++)

    {

        root->children = NULL;

    }

    // Add words to the trie

    while (fscanf(infile, “%s”, name) == 1)

    {

        node *cursor = root;

        for (int i = 0, n = strlen(name); i < n; i++)

        {

            int index = tolower(name) – ‘a’;

            if (cursor->children[index] == NULL)

            {

                // Make node

                node *new = malloc(sizeof(node));

                new->is_word = false;

                for (int j = 0; j < SIZE_OF_ALPHABET; j++)

                {

                    new->children[j] = NULL;

                }

                cursor->children[index] = new;

            }

            // Go to node which we may have just been made

            cursor = cursor->children[index];

        }

        // if we are at the end of the word, mark it as being a word

        cursor->is_word = true;

    }

    if (check(get_string(“Check word: “)))

    {

        printf(“Found!\n”);

    }

    else

    {

        printf(“Not Found.\n”);

    }

    if (!unload())

    {

        printf(“Problem freeing memory!\n”);

        return 1;

    }

    fclose(infile);

}

// TODO: Complete the check function, return true if found, false if not found

bool check(char *word)

{

     strcmp()

    return true;

        }

    return false;

}

// Unload trie from memory

bool unload(void)

{

    // The recursive function handles all of the freeing

    unloader(root);

    return true;

}

void unloader(node *current)

{

    // Iterate over all the children to see if they point to anything and go

    // there if they do point

    for (int i = 0; i < SIZE_OF_ALPHABET; i++)

    {

        if (current->children != NULL)

        {

            unloader(current->children);

        }

    }

    // After we check all the children point to null we can get rid of the node

    // and return to the previous iteration of this function.

    free(current);

}

My query is regarding bool unload(void); function. Is the parameter for it set void because it is taking input of root node from global variable root.

Replied by ChatGPT:

Yes, the `unload` function is designed to take no parameters because it is intended to operate on the global variable `root`. In this case, `root` is a pointer to the root of the trie data structure. The `unload` function uses a recursive approach to free the memory associated with each node in the trie.

Since the `root` variable is a global variable, it can be accessed directly within the `unload` function without the need to pass it as a parameter. This is a common practice when working with tree structures or other data structures where you need to traverse and modify nodes recursively.

In C, when you pass a pointer to a function, you’re passing a copy of the pointer’s value, not the actual pointer itself. Since you want to modify the original pointer (set it to `NULL` after freeing all nodes), it’s more convenient to work with the global variable directly. That’s why the `unload` function takes no parameters.

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