Working with Dictionaries in C#: The Dictionary Class for Key-Value Pair Storage

This tutorial explores C#'s `Dictionary` class, a key-value pair collection implemented using a hash table. Learn how to create dictionaries, add elements, access values using keys, iterate through key-value pairs, and leverage the efficiency of dictionaries in your C# programs.

Working with Dictionaries in C#: The `Dictionary` Class

Introduction

The `Dictionary` class in C# is a powerful collection that stores key-value pairs. It's based on a hash table, allowing for fast lookups, insertions, and removals of elements using their associated keys. Keys within a dictionary must be unique.

Key Features of `Dictionary`

• Key-Value Pairs: Stores data as key-value pairs, where each key is associated with a single value.
• Unique Keys: Keys must be unique within the dictionary. Attempting to add a duplicate key will throw an exception.
• Fast Lookups: Uses a hash table for efficient retrieval of values based on their keys.
• Namespace: Located in `System.Collections.Generic`.

Example: Creating and Iterating Through a Dictionary

This example demonstrates creating a dictionary of strings (using integer keys), adding elements using the `Add()` method, and then iterating through the key-value pairs using a `foreach` loop and the `KeyValuePair` class.

using System;
using System.Collections.Generic;

public class DictionaryExample {
    public static void Main(string[] args) {
        Dictionary<string, string> names = new Dictionary<string, string>();
        names.Add("1", "Sonoo");
        names.Add("2", "Peter");
        names.Add("3", "James");
        names.Add("4", "Ratan");
        names.Add("5", "Irfan");

        foreach (KeyValuePair<string, string> kv in names) {
            Console.WriteLine($"{kv.Key} {kv.Value}");
        }
    }
}

1 Sonoo
2 Peter
3 James
4 Ratan
5 Irfan
        

Explanation

The code creates a dictionary where both keys and values are strings. The `foreach` loop iterates through each `KeyValuePair`, allowing access to both the key and its corresponding value.

Conclusion

The `Dictionary` class is a fundamental data structure in C#. Its efficient key-based access makes it ideal for scenarios where quick retrieval of values is critical.