Introduction: Hashtable and Dictionary in C#

In C#, Hashtable and Dictionary are both used to store key-value pairs, but they have some differences in terms of usage, features, and performance. Let's delve into the details of each and provide code examples with outputs to illustrate these differences.

Hashtable in C#:

Hashtable is a collection of key/value pairs that are organized based on the hash code of the key. It is part of the System.Collections namespace. Here's an example of using Hashtable:

using System;
using System.Collections;

class Program
{
    static void Main()
    {
        // Creating a Hashtable
        Hashtable hashtable = new Hashtable();

        // Adding key-value pairs
        hashtable.Add("Name", "John");
        hashtable.Add("Age", 25);
        hashtable.Add("City", "New York");

        // Accessing values using keys
        Console.WriteLine("Name: " + hashtable["Name"]);
        Console.WriteLine("Age: " + hashtable["Age"]);
        Console.WriteLine("City: " + hashtable["City"]);
    }
}

Output:

Name: John
Age: 25
City: New York

Dictionary in C#:

Dictionary is part of the System.Collections.Generic namespace and is a generic collection of key/value pairs. It provides type safety and better performance compared to Hashtable. Here's an example:

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Creating a Dictionary
        Dictionary<string, object> dictionary = new Dictionary<string, object>();

        // Adding key-value pairs
        dictionary.Add("Name", "Jane");
        dictionary.Add("Age", 30);
        dictionary.Add("City", "Los Angeles");

        // Accessing values using keys
        Console.WriteLine("Name: " + dictionary["Name"]);
        Console.WriteLine("Age: " + dictionary["Age"]);
        Console.WriteLine("City: " + dictionary["City"]);
    }
}

Output:

Name: Jane
Age: 30
City: Los Angeles

Differences between Hashtable and Dictionary

Let's summarize the differences between Hashtable and Dictionary in the following table:

Conclusion:

In summary, while both Hashtable and Dictionary can be used to store key-value pairs, Dictionary is generally preferred in modern C# development due to its type safety, better performance, and more convenient syntax. Hashtable is considered obsolete, and unless you have specific compatibility requirements, it is recommended to use Dictionary or other modern collections provided by the System.Collections.Generic namespace.