How to declare and initialize a dictionary in C#?

Dictionary is a collection of keys and values in C#. Dictionary is included in the System.Collection.Generics namespace.

To declare and initialize a Dictionary −

IDictionary d = new Dictionary();

Above, types of key and value are set while declaring a dictionary object. An int is a type of key and string is a type of value. Both will get stored in a dictionary object named d.

Let us now see an example −

Example

using System;
using System.Collections.Generic;

public class Demo {
   public static void Main() {
      IDictionary<int, int> d = new Dictionary<int, int>();
      d.Add(1,97);
      d.Add(2,89);
      d.Add(3,77);
      d.Add(4,88);

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

Output

Dictionary elements: 4