load()函数的问题(CS50问题集5:拼写器)
我正在研究CS50的问题集5(拼写),但我不明白LOAD()函数在哪里出错。当我尝试编译时,我会在第36和79行中遇到错误。但是我不明白如何修复它。我是CS的新手,所以很抱歉这是明显的。 我认为我的问题与strcpy和strcmp函数有关,但据我了解,我正在使用CS50手动页面中指示的功能。但是,显然我缺少一些东西,否则它将有效。 先感谢您!!
// Implements a dictionary's functionality
#include <ctype.h>
#include <stdbool.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;
// TODO: Choose number of buckets in hash table
unsigned long word_count;
const unsigned int N = 26;
// Hash table
node *table[N];
// Returns true if word is in dictionary, else false
bool check(const char *word)
{
// Find hash location for current word
int h = hash(word);
// Create cursor to keep track of location on linked list at hash location
node *cursor = table[h] -> next;
while (cursor != NULL)
{
// If word is found
if (strcmp(cursor -> word, word) == 0)
{
return true;
}
// If word is not at current cursor location
else
{
cursor = cursor -> next;
}
}
// If word is not found in linked list at hash location
return false;
}
// Hashes word to a number
unsigned int hash(const char *word)
{
// TODO: Improve this hash function
return toupper(word[0]) - 'A';
}
// Loads dictionary into memory, returning true if successful, else false
bool load(const char *dictionary)
{
// Initialise number of words loaded from dictionary
word_count = 0;
// Open dictionary file from command line
FILE *dict = fopen(dictionary, "r");
if (dict == NULL)
{
return false;
}
// Read words from dictionary one by one
char buffer[LENGTH + 1];
while (fscanf(dict, "%s", buffer) != EOF)
{
// Create new node for current word
node *n = malloc(sizeof(node));
if (n == NULL)
{
return false;
}
// Copy current word to created node
strcpy(n -> word, buffer);
// Assign node to the hash table
int h = hash(buffer);
// Node does not already exist at hash location
if (table[h] -> next == NULL)
{
n -> next = NULL;
table[h] -> next = n;
}
// Node already exists at hash location
else
{
n -> next = table[h] -> next;
table[h] -> next = n;
}
// Update counter for words loaded from dictionary
word_count++;
}
fclose(dict);
// Dictionary successfully loaded
return true;
}
// Returns number of words in dictionary if loaded, else 0 if not yet loaded
unsigned int size(void)
{
return word_count;
}
// Unloads dictionary from memory, returning true if successful, else false
bool unload(void)
{
// TODO
return false;
}
I'm working on CS50's Problem Set 5 (Speller) and I don't understand where I am going wrong with the load() function. I am getting errors in lines 36 and 79 when I try to compile. But I don't understand how to fix it. I am new to CS so I am sorry if this is something obvious.
I think my issue has something to do with the strcpy and strcmp functions, but as far as I understand I am using the functions as instructed in the CS50 manual pages. However, clearly I am missing something otherwise it would be working.
Thank you in advance!!
// Implements a dictionary's functionality
#include <ctype.h>
#include <stdbool.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;
// TODO: Choose number of buckets in hash table
unsigned long word_count;
const unsigned int N = 26;
// Hash table
node *table[N];
// Returns true if word is in dictionary, else false
bool check(const char *word)
{
// Find hash location for current word
int h = hash(word);
// Create cursor to keep track of location on linked list at hash location
node *cursor = table[h] -> next;
while (cursor != NULL)
{
// If word is found
if (strcmp(cursor -> word, word) == 0)
{
return true;
}
// If word is not at current cursor location
else
{
cursor = cursor -> next;
}
}
// If word is not found in linked list at hash location
return false;
}
// Hashes word to a number
unsigned int hash(const char *word)
{
// TODO: Improve this hash function
return toupper(word[0]) - 'A';
}
// Loads dictionary into memory, returning true if successful, else false
bool load(const char *dictionary)
{
// Initialise number of words loaded from dictionary
word_count = 0;
// Open dictionary file from command line
FILE *dict = fopen(dictionary, "r");
if (dict == NULL)
{
return false;
}
// Read words from dictionary one by one
char buffer[LENGTH + 1];
while (fscanf(dict, "%s", buffer) != EOF)
{
// Create new node for current word
node *n = malloc(sizeof(node));
if (n == NULL)
{
return false;
}
// Copy current word to created node
strcpy(n -> word, buffer);
// Assign node to the hash table
int h = hash(buffer);
// Node does not already exist at hash location
if (table[h] -> next == NULL)
{
n -> next = NULL;
table[h] -> next = n;
}
// Node already exists at hash location
else
{
n -> next = table[h] -> next;
table[h] -> next = n;
}
// Update counter for words loaded from dictionary
word_count++;
}
fclose(dict);
// Dictionary successfully loaded
return true;
}
// Returns number of words in dictionary if loaded, else 0 if not yet loaded
unsigned int size(void)
{
return word_count;
}
// Unloads dictionary from memory, returning true if successful, else false
bool unload(void)
{
// TODO
return false;
}
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节点定义与发行版代码不同。
Word
应该是一个char阵列,而不是字符指针数组。node-&gt; word
是在字符串函数中使用的错误类型。The node definition is not the same as the distro code;
word
should be a char array not an array of char pointers.node->word
is the wrong type for use in the string functions.