CS50 拼字机的Valgrind和拼写错误的单词。

Question

大家好，所以我正在做哈佛的CS50，我偶然发现了一个很有趣的问题，我一直无法解决。这个程序的想法是从一个巨大的单词列表中检查哪些单词拼写错误，并在最后释放内存。这些都是我没能纠正的错误。

:) dictionary.c, dictionary.h, and Makefile exist
:) speller compiles
:( handles most basic words properly
    expected "MISSPELLED WOR...", not "MISSPELLED WOR..."
:) handles min length (1-char) words
:) handles max length (45-char) words
:) handles words with apostrophes properly
:) spell-checking is case-insensitive
:) handles substrings properly

这些都是具体的错误。

running ./speller basic/dict basic/text...
checking for output "MISSPELLED WORDS\n\n\nWORDS MISSPELLED: 0\nWORDS IN DICTIONARY: 8\nWORDS IN TEXT: 9\n"...

Expected Output:
MISSPELLED WORDS


WORDS MISSPELLED:     0
WORDS IN DICTIONARY:  8
WORDS IN TEXT:        9
Actual Output:
MISSPELLED WORDS

over

WORDS MISSPELLED:     1
WORDS IN DICTIONARY:  8
WORDS IN TEXT:        9

由于一些奇怪的原因，看似拼写错误的单词实际上是正确的。另一个错误如下。

valgrind tests failed; rerun with --log for more information.
Log
running valgrind --show-leak-kinds=all --xml=yes --xml-file=/tmp/tmpicmfiai5 -- ./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...
112 bytes in 2 blocks are still reachable in defeat record 1 of 2: (file: dictionary.c, line: 76)
336 bytes in 6 blocks are definitely lost in defeat record 2 of 2: (file: dictionary.c, line: 31)

现在我将添加我的整个代码。

// Implements a dictionary's functionality
#include <strings.h>
#include <stdbool.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "dictionary.h"


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


// Number of buckets in hash table
const unsigned int N = 27;
int word_count;
char dictionary_word[LENGTH + 1];
// Hash table
node *table[N];

// Returns true if word is in dictionary else false
bool check(const char *word)
{
    // TODO
    node *cursor = malloc(sizeof(node));
    int word_pos = hash(word);
    cursor = table[word_pos];

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

// Hashes word to a number
unsigned int hash(const char *word)
{
    int index = 0 ;
    for(int i = 0 ; word[i] != '\0' ; i++)
    {
        index += tolower(word[i]) ;
    }
    return index % N ;
}

// Loads dictionary into memory, returning true if successful else false
bool load(const char *dictionary)
{
    // open the file
    FILE *file = fopen(dictionary, "r");
    // check if file is null
    if (!file)
    {
        fprintf(stderr, "File does not exist.\n");
        return false;
    }

    char word[LENGTH + 1];

    word_count = 0;

    while(fscanf(file, "%s", dictionary_word) != EOF)
    {
        // allocate memory for the new node
        node *new_node = malloc(sizeof(node));
        if (new_node == NULL)
        {
            return false;
        }

        strcpy(new_node->word, dictionary_word);
        int hashed = hash(dictionary_word);

        if(table[hashed] == NULL)
        {
            table[hashed] = new_node;
            new_node->next = NULL;
        }
        else
        {
            new_node->next = table[hashed];
            table[hashed] = new_node->next;
        }
        word_count++;
    }

    fclose(file);
    return true;
}


// Returns number of words in dictionary if loaded else 0 if not yet loaded
unsigned int size(void)
{
    //just return the word count, easy piesey.
    return word_count;
}


// Unloads dictionary from memory, returning true if successful else false
bool unload(void)
{
    for (int i = 0; i < N; i++)
    {
        node *cursor = NULL;
        while (cursor != NULL)
        {
            node *tmp = cursor;
            cursor = cursor->next;
            free(tmp);
        }
    }
    return true;
}

非常感谢你，如果需要更多的信息，我会提供 只要我看到的消息。Thx.

Answer 1

我用你的代码运行了 small lalaland.txt，有两个内存块分配在 dictionary.c::76 在退出前没有被释放的。 以下是错误信息。你可以使用这个 联系 来重现它。 对于所有由 malloc，你需要打电话 free 一次。 您可以使用 printf 来找出哪些内存块没有被释放。最好用小字典和小文本输入来做这个调试。

 Memory access warning: memory spaces are not freed; continue execution.
 # 2 memory spaces are allocated at
 #    file:/dictionary.c::76, 26
 # total 104 bytes
 #