C Program To Implement Dictionary Using Hashing Algorithms [upd] -
Building a High-Performance Dictionary in C: A Complete Guide to Hashing Algorithms
Introduction
In the realm of computer science, a dictionary (also known as a map, symbol table, or associative array) is one of the most fundamental and versatile data structures. It allows you to store key-value pairs and retrieve values in near-constant time, regardless of the size of the data. While languages like Python, Java, and C++ have built-in dictionary implementations (e.g., dict, HashMap, std::unordered_map), the C programming language does not provide a standard one. This forces C developers to implement their own dictionary from scratch.
djb2 hash function (summary)
- Start with hash = 5381.
- For each character c: hash = ((hash << 5) + hash) + c; // hash * 33 + c
- Return hash modulo capacity as index.
Insertion:
3.1 Creating a Dictionary
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
4.4 Delete a Key-Value Pair
// Delete a key from the dictionary
int delete_key(HashTable *table, const char *key) !key) return 0; // 0 = failure
unsigned long hash = hash_djb2(key);
int index = hash % table->size;
Step 7: Advanced Optimizations
To take your dictionary to the next level, consider these improvements: c program to implement dictionary using hashing algorithms
- Quality of hash function: Poor distribution → more collisions → linked lists become longer.
- Load factor: Keep below 0.75 for open addressing, below 1.0 for chaining (but lower is better).
- Table size: Always use a prime number to reduce clustering.
Implementing a dictionary in C using hashing involves mapping unique keys to specific indices in a table (array) via a hash function. This approach provides efficient O(1) average-time complexity for common operations like insertion, searching, and deletion. Core Components Building a High-Performance Dictionary in C: A Complete
