0x1A-hash_tables

0x1A. C - Hash tables

0-hash_table_create.c

Write a function that creates a hash table.

• Prototype: hash_table_t *hash_table_create(unsigned long int size);
• Where size is the size of the array
• Return a pointer to the newly created hash table
• If something went wrong, your function should return NULL

1-djb2.c

Write a hash function implementing the djb2 algorithm.

• Prototype: unsigned long int hash_djb2(const unsigned char *str);
• You are allowed to copy and paste the function from this page

2-key_index.c

Write a function that gives you the index of a key.

• Prototype: unsigned long int key_index(const unsigned char *key, unsigned long int size);
  • Where key is the key
  • And size is the size of the array of the hash table
• This function should use the hash_djb2 function that you wrote earlier
• Return the index at which the key/value pair should be stored in the array of the hash table
• You will have to use this hash function for all the next tasks

3-hash_table_set.c

Write a function that adds an element to the hash table.

• Prototype: int hash_table_set(hash_table_t *ht, const char *key, const char *value);
  • Where ht is the hash table you want to add or update the key/value to
  • key is the key. key can not be an empty string
  • And value is the value associated with the key. value must be duplicated. value can be an empty string
• Return: 1 if it succeeded, 0 otherwise
• In case of collision, add the new node at the beginning of the list

4-hash_table_get.c

Write a function that retrieves a value associated with a key.

• Prototype: char *hash_table_get(const hash_table_t *ht, const char *key);
  • Where ht is the hash table you want to look into
  • And key is the key you are looking for
• Return the value associated with the element, or NULL if key couldn’t be found

5-hash_table_print.c

Write a function that prints a hash table.

• Prototype: void hash_table_print(const hash_table_t *ht);
  • Where ht is the hash table
• You should print the key/value in the order that they appear in the array of hash table
  • Order: array, list
• If ht is NULL, don’t print anything

6-hash_table_delete.c

Write a function that deletes a hash table.

• Prototype: void hash_table_delete(hash_table_t *ht);
• Where ht is the hash table