C Program To Implement Dictionary Using Hashing Algorithms [No Ads]

Keep the table size larger than the number of items to prevent long chains.

#include #include #include #define TABLE_SIZE 100 // Define the Node structure typedef struct Node { char *key; char *value; struct Node *next; } Node; // Define the Hash Table typedef struct { Node *buckets[TABLE_SIZE]; } HashTable; // The Hash Function (djb2) unsigned int hash(char *str) { unsigned long hash = 5381; int c; while ((c = *str++)) hash = ((hash << 5) + hash) + c; // hash * 33 + c return hash % TABLE_SIZE; } // Create a new node Node* create_node(char *key, char *value) { Node *new_node = malloc(sizeof(Node)); new_node->key = strdup(key); new_node->value = strdup(value); new_node->next = NULL; return new_node; } // Insert into the dictionary void insert(HashTable *table, char *key, char *value) { unsigned int index = hash(key); Node *new_node = create_node(key, value); // If bucket is empty, insert directly if (table->buckets[index] == NULL) { table->buckets[index] = new_node; } else { // Handle collision via Chaining new_node->next = table->buckets[index]; table->buckets[index] = new_node; } printf("Inserted: [%s : %s]\n", key, value); } // Search for a key char* search(HashTable *table, char *key) { unsigned int index = hash(key); Node *temp = table->buckets[index]; while (temp != NULL) { if (strcmp(temp->key, key) == 0) { return temp->value; } temp = temp->next; } return NULL; } int main() { HashTable dictionary = {NULL}; // Inserting values insert(&dictionary, "Apple", "A red fruit"); insert(&dictionary, "C", "A general-purpose programming language"); insert(&dictionary, "Hash", "A function that maps data"); // Searching char *key = "C"; char *result = search(&dictionary, key); if (result) { printf("\nSearch Result for '%s': %s\n", key, result); } else { printf("\n'%s' not found.\n", key); } return 0; } Use code with caution. Why Use Hashing?

Maps that large integer into the range of our array size (using the modulo operator % ). c program to implement dictionary using hashing algorithms

Hashing transforms a "key" (like a word) into an integer index. This index tells us exactly where to store the corresponding "value" (the definition) in an array. Takes a string and returns an integer.

Here is the complete C program. We use a simple but effective hashing algorithm called to minimize collisions. Keep the table size larger than the number

Dictionaries built with hashing can handle millions of entries while maintaining high performance.

Simple "sum of ASCII" functions lead to many collisions. Algorithms like djb2 or MurmurHash are much better for real-world data. Maps that large integer into the range of

Each entry in our dictionary will be a node containing the key, the value, and a pointer to the next node (for collisions).

Implementing a Dictionary in C Using Hashing In computer science, a (also known as an Associative Array or Map) is a data structure that stores data in key-value pairs. While you could use a linked list or an array to build one, search times would be slow— in the worst case.

Always use free() on your nodes and strings to prevent memory leaks in long-running programs.