c - 段错误，在 C 中初始化递归结构

Question

好的，我整理了一个问题代码的简化示例:

#include "stdio.h"
#include "string.h"

struct Trie{
    //Holds sub-tries for letters a-z
    struct Trie *sub[26];
    //Is this a substring, or a complete word?
    int is_word;
};
typedef struct Trie Trie;

Trie dictionary;

int main(int argc, char *argv[]){
    //A list of words
    char *words[7] = {"the","of","and","to","a","in","that"};

    //Add the words to the Trie structure
    int i=0, wordlen;
    Trie *sub_dict;
    for (;i<7; i++){
        //Reset
        printf("NEW WORD\n");
        sub_dict = &dictionary;
        //Add a word to the dictionary
        int j=0, c;
        while (c = words[i][j], c != '\0'){
            printf("char = %c\n",c);
            //Initialize the sub-Trie
            if (sub_dict->sub[c-97] == NULL)
                sub_dict->sub[c-97] = (Trie*) malloc(sizeof(Trie*));
            //Set as new sub-trie
            sub_dict = sub_dict->sub[c-97];
            j++;
        }
        sub_dict->is_word = 1;
    }
}

基本上，我有一个包含字母“a”到“z”的 Trie 数据结构。我有一个应该添加到 while 循环中的单词列表。不幸的是，我在循环的不同点遇到了段错误(取决于我运行它的时间)。

我猜这个问题与线路有关
sub_dict->sub[c-97] = (Trie*) malloc(sizeof(Trie*));
但我是 C 的新手，所以我完全不知道发生了什么。

Answer 1

sub_dict->sub[c-97] = (Trie*) malloc(sizeof(Trie*));有错误。

sizeof(Trie*) 在 32bit os 中会是 4，因为 Trie* 是一个指针，在 32bit os 中指针的大小是 4。你可以这样做:sub_dict->sub[c-97] = (Trie*) malloc(sizeof(Trie));