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==3139== 条件跳转或移动取决于未初始化的值

==3139== 在 0x4A0673F: strcpy (mc_replace_strmem.c:311)

==3139== by 0x400ADB: htable_insert (hashtable.c:56)

==3139== 由 0x400F25: 主要 (mylib.c:11)

大家好，我仍在尝试插入哈希表。我不能让它工作，我已经包含了我的打印方法，只是因为我认为这可能是一个问题。我正在尝试进行线性探测。当我运行 valgrind 时，我收到了这个错误，我认为这与复制到我的字符串有关，但我不确定这是什么意思？我现在真的不知道如何让这个插入工作，一些输入会很棒..
hashtable insert 中的第 56 行是 strcpy(str, key)

int htable_insert(htable h, char *str) {
   int i;
   /*convert string to integer*/
   unsigned int index = htable_word_to_int(str);
   /*calculate index to insert into hash table*/
   int remainder = index%h->capacity;
   /*once calculated position in the hash table, 3 possibilities occur*/
   /*no string in this positon, copy string to that position, increment number of keys, return 1*/
   if (h->key[remainder] == NULL) {
      char *key = emalloc(strlen(str) + 1);
      strcpy(str, key);
      h->key[remainder] = key;
      h->frequencies[remainder] = 1;
      h->num_keys++;
      return 1;
   }
   /*the exact same string is at the position, increment frequency at that position, return frequency*/
   if (strcmp(str, h->key[remainder]) == 0) {
      h->frequencies[remainder]++;
      return h->frequencies[remainder];
   }/*a string is at that position, but it isnt the rightone, keep moving along the array
      until you find either an open space or the string you are looking for*/
   if (h->key[remainder] != NULL && strcmp(str, h->key[remainder]) != 0) {
      /*you may need to wrap back around to the beginning of the table, so each time you add
        to the position you should also mod by the table capacity.*/
      for (i = 0; i <= h->capacity; i++) {
         /*no string in this positon, copy string to that position, increment number of keys*/
         if (h->key[remainder] == NULL) {
            char *key = emalloc(strlen(str) + 1);
            strcpy(str, key);
            h->key[remainder] = key;
            h->frequencies[remainder] = 1;
            h->num_keys++;
         }
         /*if you find the string you were looking for, increment the frequecny at the position
           and return the frequency*/
         if (strcmp(str, h->key[remainder]) == 0) {
            h->frequencies[remainder]++;
            return h->frequencies[remainder];
         }
         if (h->key[remainder] != NULL && h->capacity ==  i) {
            i = 0;
         }
      }   
   }
   /*if you have kept looking for an open space but there isnt one, the hash table must fu*/
   return 0;
}

void htable_print(htable h, FILE *stream) {
   int i;
   for(i = 0; i < h->capacity; i++) {
      if(h->key[i] != NULL) {
         fprintf(stream, "%d%s\n", h->frequencies[i], h->key[i]);
      }
   }
}
4

1 回答 1

1

您的 strcpy 应该是 strcpy(key, str) 而不是相反。（您可以只使用 strdup，顺便说一句，并保存 malloc+strcpy）。

另外，在： if (h->key[remainder] != NULL && strcmp(str, h->key[remainder]) != 0) {

条件 "h->key[remainder] != NULL" 是多余的：您已经在上面检查过。

最后，在你的循环中（遍历桶），它看起来像：

  1. 循环条件应该是 <，而不是 <=
  2. 您应该在某处增加余数，或使用“remainder+i”和 h->keys 的索引
  3. 代替 "capacity==i" --> "i=0"，只需使用 "(remainder+i)%capacity" 作为 h->keys 的索引

.. 最后最后——初始部分，即在循环之外的部分，可能在循环中，从而节省了代码。

于 2012-08-30T03:17:59.680 回答