I am trying to implement the check function of Speller in CS50. The code below may or may not work. But the thing that gets me is that I don't understand the bit :

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if strcasecmp(cursor-> word, tword) !=0)
    cursor= cursor-> next;

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Doesn't this mean it is comparing against itself? tword is derived from word. So surely it is comparing against itself??  

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    / Implements a dictionary's functionality

#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include "dictionary.h"

// Represents number of buckets in a hash table
#define N 26

// Represents a node in a hash table
typedef struct node
{
    char word[LENGTH + 1];
    struct node *next;
}
node;

// declare words to count in dictionary
int dictionarysize = 0;

// Represents a hash table
node *hashtable[N];

// Hashes word to a number between 0 and 25, inclusive, based on its first letter
unsigned int hash(const char *word)
{
    return tolower(word[0]) - 'a';
}

// Loads dictionary into memory, returning true if successful else false
bool load(const char *dictionary)
{
    // Initialize hash table
    for (int i = 0; i < N; i++)
    {
        hashtable[i] = NULL;
    }

    // Open dictionary
    FILE *file = fopen(dictionary, "r");
    if (file == NULL)
    {
        unload();
        return false;
    }

    // Buffer for a word
    char word[LENGTH + 1];

    // Insert words into hash table
    while (fscanf(file, "%s", word) != EOF)
    {
        // TODO
        node *new_node = malloc(sizeof(node));
        if (new_node == NULL)
        {
            unload ();
            return false;
        }
        else
        {
            strcpy (new_node -> word, word);
        }
        //implement hash function to get an index
        int index = hash(word);

        // if corresponding index in hashtable is empty, assign it to the new node
        // else append new node to the start of the linked list
        if (hashtable[index]==NULL)
        {
            hashtable[index] = new_node;
        }
        else
        {
            new_node->next = hashtable [index];
            hashtable [index] = new_node;
        }
        dictionarysize++;
    }

    // Close dictionary
    fclose(file);

    // Indicate success
    return true;
}

// Returns number of words in dictionary if loaded else 0 if not yet loaded
unsigned int size(void)
{
    // TODO
    if (dictionarysize >= 1)
    {
        return dictionarysize;
    }
    else
    {
        return 0;
    }
}

// Returns true if word is in dictionary else false
bool check(const char *word)
{
    // TODO
    {
    //find out length of word
    int lengthword = strlen(word);

    //create an array to store word
    char tword[lengthword + 1];

    // make it lowercase before hashing
    for (int i = 0; i < lengthword; i++)
    {
        tword[i] = tolower(word[i]);
    }
    tword[lengthword] = '\0';

    // hash it and find out which bucket it belongs in
    int bucket = hash(tword);
    node *cursor = hashtable [bucket];

   // compare words
    while (cursor != NULL)
    {
        if (strcasecmp(cursor->word, tword) != 0)
            cursor = cursor->next;
        else
            return true;
    }
    return false;
}



// Unloads dictionary from memory, returning true if successful else false
bool unload(void)
{
    // TODO
    return false;
}


    



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Any help gratefully accepted. Thanks.