How does dictionary works in c#

In C#, the `Dictionary<TKey, TValue>` class is used to implement a dictionary, which is essentially a type of hashtable. Here's a breakdown of how the `Dictionary<TKey, TValue>` works:

1. Key-Value Storage:

   - A `Dictionary<TKey, TValue>` stores data in key-value pairs.

   - Each key in the dictionary must be unique.

2. Hash Function:

   - Internally, the dictionary uses a hash function to convert the key into an index in the underlying array.

   - This enables quick retrieval of values based on their keys.

3. Array Storage:

   - The dictionary maintains an internal array to store the key-value pairs.

   - The index for each key is determined by the hash function.

4. Collision Handling:

   - Like other hashtables, the `Dictionary` class must handle collisions, where multiple keys hash to the same index.

   - It typically uses techniques like chaining (linked lists at each index) or open addressing.

5. Addition and Retrieval:

   - When you add a key-value pair using `Add` or `[]` notation, the hash function determines the index, and the pair is stored at that location.

   - When you retrieve a value using a key, the hash function is applied again to find the index, and the value is retrieved.

Here's an example of using `Dictionary<TKey, TValue>`:

using System;

using System.Collections.Generic;

class Program

{

    static void Main()

    {

        // Creating a dictionary with string keys and int values

        Dictionary<string, int> myDictionary = new Dictionary<string, int>();

        // Adding key-value pairs

        myDictionary.Add("one", 1);

        myDictionary["two"] = 2; // Using indexer for adding/updating

        // Retrieving values

        int value = myDictionary["one"];

        Console.WriteLine("The value for key 'one' is: " + value);

    }

}

In this example, the `Dictionary` class takes care of the details of hashing, collision resolution, and provides methods for adding, removing, and retrieving key-value pairs efficiently.