While Loop stops before condition - c

Question

I have a problem with my code. I want to load a dictionary which works fine with a small one. But when i try to load the larger version, my while loop stops at the 701th word which is " acclimatization" and then the programs continues. I searched a lot on forums and tried a lot of things, but i just can't find the reason this is caused. Does anyone have an idea of how this occurs?
Dictionary.c
bool load(const char* dictionary)
{
// reserve space for word
char* word = malloc(sizeof(char*));
// open file
FILE* dict = fopen(dictionary, "r");
if (dict == NULL)
{
fclose(dict);
fprintf(dict, "Could not load %s.\n", dictionary);
return 1;
}
root = (struct node *) malloc(sizeof(struct node));
root->is_word = false;
//Loops over word aslong the EOF is not reached
while (fgets(word,LENGTH,dict) != NULL)
{
printf("word = %s\n", word);
int word_length = strlen(word) -1;
node* current = root;
word_count++;
//Loops over letters
for (int i = 0; i < word_length; i++)
{
int index;
node *next_node;
// checks if letter isnt a apostrophe
if(word[i] == 39)
{
index = MAX_CHARS - 1;
}
// gets nummeric value of letter
else
{
index = tolower(word[i]) - 'a';
}
next_node = current->children[index];
// creates new node if letter didnt exists before
if(next_node == NULL)
{
next_node = malloc(sizeof(node));
current->children[index] = next_node;
current->is_word = false;
printf("new letter: %c\n", word[i]);
}
else
{
printf("letter: %c\n", word[i]);
}
// checks for end of the word
if(i == word_length - 1)
{
next_node->is_word = true;
}
current = next_node;
}
}
return true;
}
The node is defined by:
// node
typedef struct node
{
bool is_word;
struct node* children[27];
}
node;

Answer 1

char* word = malloc(sizeof(char*));
Depending on platform it can be 4 or 8 . You need to allocate more memory.
char* word;
word = malloc(LENGTH); // LENGTH as you use it here while (fgets(word,LENGTH,dict) != NULL)
if(word!=NULL){ // and checking if malloc is successful
// your code
free(word); // freeing allocated memory
return true;
}
else { // executed only if malloc fails
//handle error
}
You can give any desired size.
Note - Using function free() , you need to free every time you allocate memory.

Answer 2

You allocate very little space for word, it's probably 8 or 4 bytes depending on your platform.
You are allocating space for 1 char pointer, so when you read from the file LENGTH characters you can be storing bytes beyond the limits of the allocated buffer. The problem is, that the behavior is undefined thus the program might work or it might stop or anything can happen.
You don't need to allocate it dynamically, just like this it's ok
char word[100];
while (fgets(word, sizeof(word), file) != NULL) ...
/* ^ this only works with arrays, */
/* the benefit is that you can */
/* change the definition of word */
/* and resize it without changing */
/* this part. */
/* */
/* It will NOT work if you use `malloc()' */
Also, you would have a memory leak if fopen() failes, every malloc() requires a corresponding free().
Suggestion:
for (int i = 0; i < word_length; i++)
can be written like this too
for (int i = 0; ((word[i] != '\n') && (word[i] != '\0')); i++)
and you avoid calling strlen() which will also iterate through the characters.