I am currently taking CS50x and am on Pset5: Speller. My code works as intended, however when I run the check50 function my program fails Valgrind.
This is particularly confusing to me because when I run Valgrind on my program with the help50, it passes with no memory leaks. I ran help50 Valgrind on my program after changing the default dictionary to the dictionaries/small, and it still passed.
Her is my code and the error log I get from check50. I suspect my Load() function is the culprit, perhaps something to do with the fopen. I have wondered if I needed to add fclose() for the dictionary, but when I add that line to the end of Load() I get a "munmap_chunk(): invalid pointer" when I try to compile.
If anyone could help me out or had any idea where I should look I would be most grateful!
// Implements a dictionary's functionality
#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>
#include "dictionary.h"
// Represents a node in a hash table
typedef struct node
{
char word[LENGTH + 1];
struct node *next;
}
node;
// Number of bucket for Hash Table
const unsigned int N = 676;
// Hash table
node *table[N];
int word_counter = 0;
// Returns true if word is in dictionary, else false
bool check(const char *word)
{
// TODO
int index = hash(word);
node *cursor = table[index];
//printf("cursor: %s\n", cursor->word);
while (cursor != NULL)
{
if (strcasecmp(word, cursor->word) == 0)
{
return true;
}
cursor = cursor->next;
}
return false;
}
// Hashes word to a number
unsigned int hash(const char *word)
{
// TODO: Improve this hash function
unsigned int index = 0;
for (int i = 0; i < 26; i++)
{
if (word[0] == i + 'a' || word[0] == i + 'A')
{
index += i * 26;
}
if (word[1] == i + 'a' || word[1] == i + 'A')
{
index += i;
}
}
return index;
}
// Loads dictionary into memory, returning true if successful, else false
bool load(const char *dictionary)
{
FILE *dict_file = fopen(dictionary, "r");
if (dict_file == NULL)
{
return false;
}
table_clear();
// Use fscanf() to look at each string in the dictionary and store to buffer
char *buffer = malloc(sizeof(LENGTH + 1));
if (buffer == NULL)
{
return false;
}
while (fscanf(dict_file, "%s", buffer) != EOF)
{
// Create a new memory space for each dictionary word, and store it here
node *n = malloc(sizeof(node));
if (n == NULL)
{
free(buffer);
return false;
}
// Copy each word from buffer to the location (*dict_entry).word
strcpy(n->word, buffer);
n->next = NULL;
// Use hash function to find the hash value of the dictionary word
int index = hash(n->word);
if (table[index] != NULL)
{
n->next = table[index];
}
table[index] = n;
n = NULL;
free(n);
word_counter++;
}
//fclose(dict_file); <----- If activate, this line causes the munmap_chunk: invalid pointer error
free(buffer);
return true;
}
// Returns number of words in dictionary if loaded, else 0 if not yet loaded
unsigned int size(void)
{
return word_counter;
}
// Unloads dictionary from memory, returning true if successful, else false
bool unload(void)
{
for (int i = 0; i < N; i++)
{
node *cursor = table[i];
while (cursor != NULL)
{
cursor = cursor->next;
free(table[i]);
table[i] = cursor;
}
free(cursor);
}
return true;
}
// Sets every value in table to NULL
void table_clear(void)
{
for (int i = 0; i < N; i++)
{
table[i] = NULL;
}
return;
}
**Cause valgrind tests failed; see log for more information
LOG:
running valgrind --show-leak-kinds=all --xml=yes --xml-file=/tmp/tmpr2rknwok -- ./speller substring/dict substring/text...
checking for output "MISSPELLED WORDS\n\nca\ncats\ncaterpill\ncaterpillars\n\nWORDS MISSPELLED: 4\nWORDS IN DICTIONARY: 2\nWORDS IN TEXT: 6\n"...
checking that program exited with status 0...
checking for valgrind errors...
Invalid write of size 1: (file: dictionary.c, line: 88)
Invalid read of size 1: (file: dictionary.c, line: 99)
472 bytes in 1 blocks are still reachable in loss record 1 of 1: (file: dictionary.c, line: 74)
See above for exlaination
