C# Hashtable

C# Hashtable

In C# the Hashtable is a non-generic collection that stores key-value pairs. It is available under System. Collections namespace. It is like the Dictionary collection. All the keys and values are object data types. Hashtable also cannot have a duplicate key, but the values can be duplicated.

Let’s see the example code of Hashtable in C#.

 
using System;
using System.Collections;
using System.Collections.Generic;

namespace ConsoleAppDemo
{
    class Program
    {
        static void Main(string[] args)
        {

            Hashtable someData = new Hashtable();
            someData.Add(1, "One");
            someData.Add(2, "Two");
            someData.Add(3, "Three");
            someData.Add(4, "Four");
            
            Console.WriteLine(someData[1]); //Output: One

            //Access the Hashtable collection values
            foreach (DictionaryEntry item in someData)
            {
                Console.WriteLine(item.Key + " " + item.Value);
            }


            Console.ReadKey();
        }
    }
}
    

Output:

4 Four
3 Three
2 Two
1 One

Let's see with another example of Hashtable using collection-initializer syntax.

 
using System;
using System.Collections;
using System.Collections.Generic;

namespace ConsoleAppDemo
{
    class Program
    {
        static void Main(string[] args)
        {

            var someCities = new Hashtable() {
                {"USA", "Kentucky, New York, Chicago"},
                {"UK", "London, Manchester, Birmingham"},
                {"Nepal", "Kathmandu, Pokhara, Dhulikhel"}

            };
            
            Console.WriteLine(someCities["Nepal"]); //Output: Kathmandu, Pokhara, Dhulikhel

            //Access the Hashtable collection values
            foreach (DictionaryEntry item in someCities)
            {
                Console.WriteLine(item.Key + " " + item.Value);
            }


            Console.ReadKey();
        }
    }
}
    

Output:

Key = Nepal, Value = Kathmandu, Pokhara, Dhulikhel
Key = USA, Value = Kentucky, New York, Chicago
Key = UK, Value = London, Manchester, Birmingham