Question

我正在研究散列表，但没有走得太远。我的问题是如何将表格设置为大小。（请阅读以下说明以获得澄清）。

这就是我应该做的：

/**
 * Create a new instance of struct hashStorage and return it. It sets the size of the
 * table to be of length "size" which will be the number of the entries in the hash. It takes also an
 * argument to specify the format of the order printed to an output stream. If myHash parameter
 * is NULL then this means that the hash should be a linked list. When myHash is NULL the size
 * parameter should be ignored.
 */

struct hashStorage {
    int    (*funcHash)  (int);
    void   (*printItem) (struct order *, FILE *);
    struct onode**      table;
    int    size;
};

struct hashStorage* createHash(int size, int (*myHash)(int),void(*printOrder)(struct order *, FILE *))
{
     struct hashStorage* hashList = (struct hashStorage*) malloc(sizeof(struct hashStorage));

     hashList->table;

    if(myHash == NULL)
    {

    }
    else
    {

    }
     return hashList;
}

如果有人可以解释我给予和示例将是一个很大的帮助。

Answer 1

您试图设置已分配对象的值。你面临的障碍是：

出于某种原因，您想要合并链表和哈希表数据结构？这是愚蠢的，但无论如何......
malloc并不一定会返回指向对象的指针;它可能会返回NULL。你需要在继续之前检查一下。
您指定malloc的返回值的对象不是您要分配的对象，因此hashList = ...无法正常工作;您需要使用*hashlist = ...或hashlist->member = ...。

以下是我将如何编写此代码：

typedef size_t hash_fn(int);
typedef void print_fn(struct order *, FILE *);

struct hash_table {
    size_t       size;
    hash_fn      *hash_function;
    print_fn     *print_function;
    struct onode *item[];
};

struct hash_table *create_hash_table(size_t size, hash_fn *hash_function, print_fn *print_function)
{
    if (hash_function == NULL)
    {
        /* This should give you enough to implement your linked list;
         * use hash_table->item[0] as your item and hash_table->item[1]
         * as your link. */
        size = 2;
    }

    struct hash_table *hash_table = malloc(sizeof *hash_table
                                         + size * sizeof *hash_table->table);
    if (hash_table == NULL)
    {
        return NULL;
    }

    *hash_table = (struct hash_table) { .size = size
                                      , .hash_function = hash_function
                                      , .print_function = print_function };

    return hash_table;
}

使用struct的Hashtable

1 个答案: