Question

I have the following construction:

typedef struct bucket {     char *key;     ENTRY *data;     struct bucket *next; } bucket;  typedef struct {     size_t size;     bucket **table; } hash_table; 

But I have no idea how to allocate memory for that. I tried:

hash_table* ht = malloc(sizeof(hash_table)*101); 

in order to create a hashtable for 101 entries but it din’t work! Can anyone help me? I would really appreciate it!

Answer 1

Not quite. Assuming this is C, you probably want to make a function:

 hash_table* init_table(size_t size) {      size_t i;      hash_table* ht = (hash_table*)malloc(sizeof(hash_table));      if (ht == NULL) return NULL;      ht->size = size;      ht->table = (bucket**)malloc(sizeof(bucket*)*size);      if (ht->table == NULL) {          free(ht);          return NULL;      }      for (i = 0; i < size; ++i) {          ht->table[i] = NULL;      }      return ht;  } 

You might need some other fields in that struct.

If you wanted to be tricky, and never realloc the bucket, you can do this:

 hash_table* init_table(size_t size) {      hash_table* ht = (hash_table*)malloc(sizeof(hash_table)+sizeof(bucket)*size);      if (ht == NULL) return NULL;      ht->size = size;      ht->table = (bucket**)(ht+1);      for (i = 0; i < size; ++i) {          ht->table[i] = NULL;      }      return ht;  } 

EDIT: I fixed my bucket* table’s to bucket**

EDIT2: I’ve gotten rid of the memsets and added error checking for malloc.