C# Hashtable Class

// C# Program to demonstrates Hashtable
using System;
using System.Collections;

class Geeks {
    static void Main()
    {
        // Create a Hashtable of string 
        // keys and integer values
        Hashtable ht = new Hashtable();

        // Adding elements to the Hashtable
        ht.Add("One", 1);
        ht.Add("Two", 2);
        ht.Add("Three", 3);

        Console.WriteLine("Hashtable Elements:");
        foreach(DictionaryEntry i in ht)
        {
            Console.WriteLine($"{i.Key}: {i.Value}");
        }
    }
}

// Using Hashtable() Constructor
using System;
using System.Collections;

class Geeks {
    static void Main()
    {
        // Initialize Hashtable
        Hashtable ht1 = new Hashtable();
        Hashtable ht2 = new Hashtable();

        // Inserting elements using Add() method
        ht1.Add(1, "one");
        ht1.Add(2, "two");
        ht1.Add(3, "three");

        ht2.Add(4, "four");
        ht2.Add(5, "five");
        ht2.Add(6, "six");

        // Print mappings to the console
        Console.WriteLine("Mappings of ht1: ");
        foreach(DictionaryEntry i in ht1)
        {
            Console.WriteLine($"{i.Key} - {i.Value}");
        }

        Console.WriteLine("Mappings of ht2: ");
        foreach(DictionaryEntry i in ht2)
        {
            Console.WriteLine($"{i.Key} - {i.Value}");
        }
    }
}

// C# program to demonstrates the use 
// of IsSynchronized and Count property
using System;
using System.Collections;

class Geeks {

    static void Main(string[] args)
    {

        // create and initialize Hashtable using Add() method
        Hashtable h1 = new Hashtable();
        h1.Add("1", "Welcome");
        h1.Add("2", "to");
        h1.Add("3", "geeks");
        h1.Add("4", "for");
        h1.Add("5", "geeks");


        // Creating a synchronized packing around the Hashtable
        Hashtable h2 = Hashtable.Synchronized(h1);

        // print the status of both Hashtables
        Console.WriteLine("h1 Hashtable is {0}.",
                h1.IsSynchronized ? "synchronized" : "not synchronized");

        Console.WriteLine("h2 Hashtable is {0}.",
                h2.IsSynchronized ? "synchronized" : "not synchronized");

        // Using Count Property
        Console.WriteLine("Total Number of Elements in h1: " + h1.Count);
    }
}

// C# program to demonstrate the working of Add()
// and Remove() Methods
using System;
using System.Collections;

class Geeks {

    static void Main(string[] args)
    {
        // create and initialize Hash table
        // using Add() method
        Hashtable ht = new Hashtable();
        ht.Add("1", "Geek1");
        ht.Add("2", "Geek2");
        ht.Add("3", "Geek3");
        ht.Add("4", "Geek4");
        ht.Add("5", "Geek5");

        ICollection k = ht.Keys;

        Console.WriteLine("Hashtable Contains:");

        foreach(var i in k)
        {
            Console.WriteLine(i + "-" + ht[i]);
        }

        Console.WriteLine();

        // Remove element 4
        // using Remove() method
        ht.Remove("4");
        ht.Remove("5");

        // printing updated Hash table
        Console.WriteLine("Hashtable after removing element 4:");

        foreach(var i in k)
        {
            Console.WriteLine(i + "-" + ht[i]);
        }
    }
}