Difference between Dictionary and Hashtable in C#

Hashtable is slower than Dictionary. For strongly-typed collections, the Dictionary collection is faster.

Hashtable

Hashtable class represents a collection of key-and-value pairs that are organized based on the hash code of the key. It uses the key to access the elements in the collection.

Let us see an example −

Example

using System;
using System.Collections;

namespace Demo {
   class Program {
      static void Main(string[] args) {
         Hashtable ht = new Hashtable();

         ht.Add("E001", "Tom");
         ht.Add("E098", "Amit");
         ht.Add("E110", "Jack");

         ICollection key = ht.Keys;

         foreach (string k in key) {
            Console.WriteLine(k + ": " + ht[k]);
         }
         Console.ReadKey();
      }
   }
}

Output

E001: Tom
E098: Amit
E110: Jack

Dictionary

Dictionary is a collection of keys and values in C#. Dictionary<TKey, TValue> is included in the System.Collection.Generics namespace.

Example

using System;
using System.Collections.Generic;

public class Demo {
   public static void Main() {

      IDictionary<int, int> dict = new Dictionary<int, int>();
      dict.Add(1,234);
      dict.Add(2,489);
      dict.Add(3,599);
      dict.Add(4,798);
      dict.Add(5,810);
      dict.Add(6,897);
      dict.Add(7,909);

      Console.WriteLine("Dictionary elements: "+dict.Count);
   }
}

Output

Dictionary elements: 7