我的加载函数不断出现段错误。
bool load(const char *dictionary)
{
//create a trie data type
typedef struct node
{
bool is_word;
struct node *children[27]; //this is a pointer too!
}node;
//create a pointer to the root of the trie and never move this (use traversal *)
node *root = malloc(sizeof(node));
for(int i=0; i<27; i++)
{
//NULL point all indexes of root -> children
root -> children[i] = NULL;
}
FILE *dptr = fopen(dictionary, "r");
if(dptr == NULL)
{
printf("Could not open dictionary\n");
return false;
}
char *c = NULL;
//scan the file char by char until end and store it in c
while(fscanf(dptr,"%s",c) != EOF)
{
//in the beginning of every word, make a traversal pointer copy of root so we can always refer back to root
node *trav = root;
//repeat for every word
while ((*c) != '\0')
{
//convert char into array index
int alpha = (tolower(*c) - 97);
//if array element is pointing to NULL, i.e. it hasn't been open yet,
if(trav -> children[alpha] == NULL)
{
//then create a new node and point it with the previous pointer.
node *next_node = malloc(sizeof(node));
trav -> children[alpha] = next_node;
//quit if malloc returns null
if(next_node == NULL)
{
printf("Could not open dictionary");
return false;
}
}
else if (trav -> children[alpha] != NULL)
{
//if an already existing path, just go to it
trav = trav -> children[alpha];
}
}
//a word is loaded.
trav -> is_word = true;
}
//success
free(root);
return true;
}
我检查了初始化期间是否正确地将新指针指向 NULL。我有三种类型的节点:根节点、遍历节点(用于移动)和下一个节点。 (i.) 在分配节点之前,我是否可以将节点设置为空? (ii.) 另外,如果“next_node”节点在 if 语句内初始化并分配,我该如何释放该节点? node *next_node = malloc(sizeof(node));
(iii.) 如果我想将节点设置为全局变量,哪些应该是全局变量? (iv.) 最后,在哪里设置全局变量:在speller.c 的main 内部、main 外部,还是其他地方?问题很多,所以您不必回答所有问题,但如果您能回答已回答的问题,那就太好了!请指出我的代码中的任何其他特性。应该有很多。我会接受大多数答案。
最佳答案
段错误的原因是指针“c”没有分配内存。
另外,在你的程序中 -
//scan the file char by char until end and store it in c
while(fscanf(dptr,"%s",c) != EOF)
一旦为指针 c 分配了内存,c 将保存从文件字典中读取的单词。 在下面的代码中,您正在检查“\0”字符-
while ((*c) != '\0')
{
但是您没有移动 c 指针来指向读取的字符串中的下一个字符,因为该代码最终将执行无限 while 循环。 你可以尝试这样的事情-
char *tmp;
tmp = c;
while ((*tmp) != '\0')
{
......
......
//Below in the loop at appropriate place
tmp++;
}
关于c - 加载函数 trie 段错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/46052907/