Question

我在尝试将字符串哈希到哈希表时尝试调试哈希函数。以下代码是我的源文件，我还将发布valgrind错误消息。任何反馈错误都将非常感激。在3个函数中发布的是我收到错误的地方。在我的函数hashQ中我尝试传递给add_string函数my_hash_table和char * str，我得到的valgrind错误如下：再次提供任何帮助将非常感谢!!

==17194== Invalid read of size 8
==17194==    at 0x400D63: lookup_string (hash.c:57)
==17194==    by 0x400DF3: add_string (hash.c:76)
==17194==    by 0x401187: display (queue.c:68)
==17194==    by 0x400BE1: main (compare.c:85)
==17194==  Address 0x5aa01ac58 is not stack'd, malloc'd or (recently) free'd
==17194==
==17194==
==17194== Process terminating with default action of signal 11 (SIGSEGV)
==17194==  Access not within mapped region at address 0x5AA01AC58
==17194==    at 0x400D63: lookup_string (hash.c:57)
==17194==    by 0x400DF3: add_string (hash.c:76)
==17194==    by 0x401187: display (queue.c:68)
==17194==    by 0x400BE1: main (compare.c:85)

另外，我的hash.h文件如下：

#ifndef HASH_H
#define HASH_H

typedef struct _list_t_{
    char *string;
    struct _list_t_ *next;
} list_t;

typedef struct _hash_table_t_{
    int size;
    list_t **table;
} hash_table_t;

//creation of a hash_table
hash_table_t *create_hash_table(int size);

//hash function
unsigned long hash(char *str);

//string lookup
list_t *lookup_string(hash_table_t *hashtable, char *str);

//inserting a string
int add_string(hash_table_t *hashtable, char *str);

//Deleting a table
void free_table(hash_table_t *hashtable);

int count_strings(hash_table_t *hashtable);

#endif



 unsigned long hash(char *str)
    {
            unsigned long hashval = 5381;
            int c;

            while((c = *str++))
          hashval = ((hashval << 5) + hashval) + c;   /* hashval * 33 + c */

       return hashval;
    }

    list_t *lookup_string(hash_table_t *hashtable, char *str)
    {
        printf("1");
        list_t *list;
        printf("2");
        unsigned int hashval = hash(str);
        printf("3");
        //go to the correct list based on the hash value and see if str is
        //in the list. If it is, return a pointer to the list element.
        // if not, the item isnt in the table, return NULL

      for(list = hashtable->table[hashval]; list != NULL; list = list->next)                      {
            if(strcmp(str, list->string) == 0)
            return list;
        }

        return NULL;
    }

        int add_string(hash_table_t *hashtable, char *str)
        {
            list_t *new_list;
            list_t *current_list;
            unsigned int hashval = hash(str);

            //allocate memory for list
            if((new_list = malloc(sizeof(list_t))) == NULL)
            return 1;

            //check to see if the item already exist
            current_list = lookup_string(hashtable, str);
            //item already exists, dont insert it again
            if(current_list != NULL) return 2;
            //insert into list
            new_list->string = strdup(str);
            new_list->next = hashtable->table[hashval];
            hashtable->table[hashval] = new_list;

            return 0;
        }

Answer 1

如果有人在观看，我确实找到了答案，我的哈希函数使我的哈希值变大了，我在查询字符串函数中使用了它，它超出了我的哈希表的界限所以我是gdb和Valgrind的。我会弯曲我的讨厌的肌肉，现在走来走去。快乐编码!!!!

我的哈希函数的错误我似乎无法弄清楚

1 个答案: