我正在尝试实现一个trie数据结构来对给定的文本文件进行拼写检查。目前，它似乎适用于文件中的几个单词，然后它遇到了 seg 错误。我尝试调试以找到罪魁祸首，但我发现"letter"的值保留了看似随机的负值(它应该在 1 到 27 之间，包括 1 和 27(。通常，seg故障问题在我启动程序后几乎立即出现，所以我不确定为什么问题会在程序中间弹出。
/**
* Implements a dictionary's functionality.
*/
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include "dictionary.h"
//create global root node
Trienode *root;
//create word counter for size() function
unsigned int wordcount = 0;
//creates an empty node
Trienode * newnode()
{
Trienode *nnode = NULL;
nnode = (Trienode *)malloc(sizeof(Trienode));
//initialize new node with null pointers and values
nnode -> parent = NULL;
for(int i = 0; i < 27; i++)
{
nnode -> children[i] = NULL;
}
return nnode;
}
void cleartrie(Trienode *head)
{
//if child node exists, free it, else continue with next iteration in for loop
if(head)
{
for(int i = 0; i < 27; i++)
{
cleartrie(head -> children[i]);
}
free(head);
head = NULL;
}
}
/**
* Returns true if word is in dictionary else false.
*/
bool check(const char *word)
{
int i = 0;
int letter;
Trienode *head = root;
while(word[i] != ' ')
{
if(isalpha(word[i]))
{
letter = word[i] - 'a';
}
else //it must be an apostrophe
{
letter = word[i] - 13;
}
if(!(head -> children[letter]))
{
return false;
}
else //a pointer must exist
{
head = head -> children[letter];
}
i++;
}
return true;
}
/**
* Loads dictionary into memory. Returns true if successful else false.
*/
bool load(const char *dictionary)
{
//open file
FILE *infile = fopen(dictionary, "r");
Trienode *parnode; //parent node
root = newnode();
Trienode *curnode = root; //current node
int letter = 0;
//while not end of file, read words
while(fgetc(infile) != EOF)
{
//while not end of word, read letters
for(;;)
{
int c;
//read current letter in file
c = fgetc(infile);
//convert input char to corresponding array location (a - z = 0-25, apostrophe = 26)
if(isalpha(c))
{
letter = c - 'a';
}
else if (c == ''')
{
letter = c - 13;
}
//if end of string, exit loop
else if (c == ' ')
{
//end of word, so endofstring = true
wordcount++;
break;
}
//move to next letter if not either apostrophe or alphabetical
else
{
break;
}
//if pointer to letter of word doesn't exist, create new node
if(curnode -> children[letter] == NULL)
{
curnode -> children[letter] = newnode();
}
//child node is the new current node
parnode = curnode;
curnode = curnode -> children[letter];
curnode -> parent = parnode;
}
//return to root node
curnode = root;
}
fclose(infile);
return true;
}
/**
* Returns number of words in dictionary if loaded else 0 if not yet loaded.
*/
unsigned int size(void)
{
return wordcount;
}
/**
* Unloads dictionary from memory. Returns true if successful else false.
*/
bool unload(void)
{
cleartrie(root);
if (root == NULL)
{
return true;
}
return false;
}
对不起，文字墙，但大部分只是为了上下文(我希望(。赛格故障错误发生在 if(！(头 ->子[字母](( 检查助手函数的行。
提前感谢！
我怀疑您的测试文件可能包含一些大写字母。如果是这种情况，则减去'a'以尝试重新映射您的字母将导致负数，因为'A' < 'a'.看看 ASCII 表。首先将字母转换为小写应该可以解决您的问题。