How to create an OrderedDictionary in C#

Last Updated : 11 Jul, 2025
OrderedDictionary() constructor is used to initialize a new instance of the OrderedDictionary class which will be empty and will have the default initial capacity. OrderedDictionary Class represents a collection of key/value pairs that are accessible by the key or index. It is present in System.Collections.Specialized namespace. Syntax: 
public OrderedDictionary();
Example 1: csharp 
// C# Program to illustrate how
// to create a OrderedDictionary
using System;
using System.Collections;
using System.Collections.Specialized;

class Geeks {

    // Main Method
    public static void Main(String[] args)
    {

        // od is the OrderedDictionary object
        // OrderedDictionary() is the constructor
        // used to initializes a new
        // instance of the OrderedDictionary class
        OrderedDictionary od = new OrderedDictionary();

        // Count property is used to get the
        // number of elements in OrderedDictionary
        // It will give 0 as no elements
        // are present currently
        Console.WriteLine("The number of elements: "
                                           +od.Count);
    }
}
Output: 
The number of elements: 0
Example 2: csharp 
// C# Program to illustrate how
// to create a OrderedDictionary
using System;
using System.Collections;
using System.Collections.Specialized;

class Geeks {

    // Main Method
    public static void Main(String[] args)
    {

        // od is the OrderedDictionary object
        // OrderedDictionary() is the constructor
        // used to initializes a new
        // instance of the OrderedDictionary class
        OrderedDictionary od = new OrderedDictionary();

        Console.Write("Before Add Method: ");

        // Count property is used to get the
        // number of elements in OrderedDictionary
        // It will give 0 as no elements
        // are present currently
        Console.WriteLine(od.Count);

        // Adding key/value pairs in od
        od.Add("1", "C");
        od.Add("2", "C++");
        od.Add("3", "Java");
        od.Add("4", "C#");

        Console.Write("After Add Method: ");

        // Count property is used to get the
        // number of elements in ld
        Console.WriteLine(od.Count);
    }
}
Output: 
Before Add Method: 0
After Add Method: 4
Reference:
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