Question

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

#include "dictionary.h"

#define HASH_SIZE 100

// prototype
int hash(char *word);

// counter
int counter;

// node
typedef struct
{
    char *word;
    node *next;
} node;

// hash table
node *hashtable[HASH_SIZE];

bool
load(const char *dictionary)
{
    // open the dictionary
    FILE *dict = fopen(dictionary, "r");
    if(dict == NULL)
    {
        printf("Could not open %s.\n", dictionary);
        return false;
    }

    // set all values in the hash table to null
    for(int i = 0; i < HASH_SIZE; i++)
    {
        hashtable[i] = NULL;
    }

    // set the counter to 0
    counter = 0;

    // iterate through the words in the dictionary
    while (!feof(dict))
    {
        // get word into a string
        char gotcha[LENGTH];
        fscanf(dict, "%s", gotcha);

        // declare a node and allocate memory
        node n;
        n.word = malloc( strlen(gotcha)*sizeof(char) );

        // save the word into the node
        strcpy(n.word, gotcha);

        // hash the word, baby!
        int hash_value = hash(n.word);

        // start saving addresses to the hashtable
        n.next = hashtable[hash_value];
        hashtable[hash_value] = &n;

        //test
        int len = strlen(n.word);
        printf("%s\n", n.word);
        printf("%i\n", len);

        // that's one more!
        counter++;
    }


    fclose(dict);

    return true;
}

I am receiving the following two errors on these two lines of code:

    n.next = hashtable[hash_value];
    hashtable[hash_value] = &n;

dictionary.c:89:16: error: assignment from incompatible pointer type [-Werror]
dictionary.c:90:31: error: assignment from incompatible pointer type [-Werror]
How do I save pointer values in these two places? I am new to this, so please bear that in mind. 🙂

Answer 1

In your structure, the type node is not yet defined. Change it to use the structure tag:

typedef struct node
{
    char *word;
    struct node *next;
} node;