C Program To Implement Dictionary Using Hashing Algorithms Official

A dictionary entry needs a , a value , and a pointer to the next entry in case of a hash collision.

// Helper: create a new node KeyValuePair* create_pair(const char *key, int value) KeyValuePair *new_pair = (KeyValuePair*)malloc(sizeof(KeyValuePair)); if (!new_pair) return NULL; new_pair->key = strdup(key); // Allocate and copy string new_pair->value = value; new_pair->next = NULL; c program to implement dictionary using hashing algorithms

This implementation uses to resolve collisions. Instead of storing data directly in the array slot, each slot points to the head of a singly linked list. All items that hash to the same index are appended to that list. Architectural Layout A dictionary entry needs a , a value

#include #include #include #define TABLE_SIZE 10007 // A prime number minimizes clustering // Define the structure for a dictionary node typedef struct DictNode char *key; int value; struct DictNode *next; DictNode; // Define the Hash Table structure typedef struct DictNode *buckets[TABLE_SIZE]; Dictionary; // DJB2 Hashing Algorithm unsigned int hash_function(const char *key) unsigned long hash = 5381; int c; while ((c = *key++)) hash = ((hash << 5) + hash) + c; // hash * 33 + c return hash % TABLE_SIZE; // Initialize the dictionary Dictionary* create_dictionary() Dictionary *dict = (Dictionary*)malloc(sizeof(Dictionary)); if (!dict) perror("Failed to allocate memory for dictionary"); exit(EXIT_FAILURE); for (int i = 0; i < TABLE_SIZE; i++) dict->buckets[i] = NULL; return dict; // Insert or update a key-value pair void dict_insert(Dictionary *dict, const char *key, int value) unsigned int index = hash_function(key); DictNode *current = dict->buckets[index]; // Check if the key already exists to update its value while (current != NULL) if (strcmp(current->key, key) == 0) current->value = value; return; current = current->next; // Key does not exist, create a new node DictNode *new_node = (DictNode*)malloc(sizeof(DictNode)); if (!new_node) perror("Failed to allocate memory for node"); exit(EXIT_FAILURE); new_node->key = strdup(key); // Duplicate string to ensure ownership new_node->value = value; // Insert at the beginning of the chain (O(1) insertion) new_node->next = dict->buckets[index]; dict->buckets[index] = new_node; // Search for a value by key // Returns 1 if found and updates the value pointer, 0 otherwise int dict_search(Dictionary *dict, const char *key, int *found_value) unsigned int index = hash_function(key); DictNode *current = dict->buckets[index]; while (current != NULL) if (strcmp(current->key, key) == 0) *found_value = current->value; return 1; // Success current = current->next; return 0; // Not found // Delete a key-value pair from the dictionary int dict_delete(Dictionary *dict, const char *key) unsigned int index = hash_function(key); DictNode *current = dict->buckets[index]; DictNode *prev = NULL; while (current != NULL) if (strcmp(current->key, key) == 0) if (prev == NULL) // Node to delete is the head of the chain dict->buckets[index] = current->next; else // Node to delete is in the middle or end prev->next = current->next; free(current->key); free(current); return 1; // Deleted successfully prev = current; current = current->next; return 0; // Key not found // Free all memory allocated for the dictionary void free_dictionary(Dictionary *dict) for (int i = 0; i < TABLE_SIZE; i++) DictNode *current = dict->buckets[i]; while (current != NULL) DictNode *temp = current; current = current->next; free(temp->key); free(temp); free(dict); // Driver program to demonstrate functionality int main() Dictionary *my_dict = create_dictionary(); // Inserting pairs dict_insert(my_dict, "alice", 25); dict_insert(my_dict, "bob", 30); dict_insert(my_dict, "charlie", 35); // Updating an existing key dict_insert(my_dict, "alice", 26); // Searching items int value; if (dict_search(my_dict, "alice", &value)) printf("Found 'alice' with value: %d\n", value); else printf("'alice' not found.\n"); if (dict_search(my_dict, "unknown", &value)) printf("Found 'unknown' with value: %d\n", value); else printf("'unknown' not found.\n"); // Deleting an item if (dict_delete(my_dict, "bob")) printf("Deleted 'bob' successfully.\n"); // Confirming deletion if (!dict_search(my_dict, "bob", &value)) printf("'bob' is no longer in the dictionary.\n"); // Clean up memory free_dictionary(my_dict); return 0; Use code with caution. Technical Breakdown of Operations 1. Collision Handling Strategy All items that hash to the same index

// Structure to represent the Hash Table struct HashTable struct DictionaryItem* table[SIZE]; // Array of pointers to DictionaryItems ;

The following complete program implements a dictionary with string keys and integer values. It handles dynamic memory allocation, collision resolution via chaining, and proper memory cleanup.

free(old_buckets);