Insert a new entry in OrderedDictionary with specified key and value in C#

The OrderedDictionary class in C# provides the Insert method to add a new entry at a specific position while maintaining the order of existing elements. This method allows you to specify both the index position and the key-value pair to insert.

Syntax

Following is the syntax for inserting an entry at a specific position in an OrderedDictionary −

orderedDictionary.Insert(index, key, value);

Parameters

• index − The zero-based index at which to insert the key-value pair.

• key − The key of the entry to insert.

• value − The value of the entry to insert.

How It Works

When you call the Insert method, the new key-value pair is inserted at the specified index position. All existing entries at that position and beyond are shifted to higher indices to accommodate the new entry.

Using Insert Method

Example 1: Inserting at Specific Position

using System;
using System.Collections;
using System.Collections.Specialized;

public class Demo {
   public static void Main(){
      OrderedDictionary dict = new OrderedDictionary();
      dict.Add("1", "One");
      dict.Add("2", "Two");
      dict.Add("3", "Three");
      dict.Add("4", "Four");
      dict.Add("5", "Five");
      dict.Add("6", "Six");
      dict.Add("7", "Seven");
      dict.Add("8", "Eight");
      Console.WriteLine("Elements...");
      IDictionaryEnumerator demoEnum = dict.GetEnumerator();
      while (demoEnum.MoveNext()) {
         Console.WriteLine("Key = " + demoEnum.Key + ", Value = " + demoEnum.Value);
      }
      dict.Insert(7, "15", "Fifteen");
      Console.WriteLine("Elements...UPDATED");
      demoEnum = dict.GetEnumerator();
      while (demoEnum.MoveNext()) {
         Console.WriteLine("Key = " + demoEnum.Key + ", Value = " + demoEnum.Value);
      }
   }
}

The output of the above code is −

Elements...
Key = 1, Value = One
Key = 2, Value = Two
Key = 3, Value = Three
Key = 4, Value = Four
Key = 5, Value = Five
Key = 6, Value = Six
Key = 7, Value = Seven
Key = 8, Value = Eight
Elements...UPDATED
Key = 1, Value = One
Key = 2, Value = Two
Key = 3, Value = Three
Key = 4, Value = Four
Key = 5, Value = Five
Key = 6, Value = Six
Key = 7, Value = Seven
Key = 15, Value = Fifteen
Key = 8, Value = Eight

Example 2: Inserting in the Middle

using System;
using System.Collections;
using System.Collections.Specialized;

public class Demo {
   public static void Main(){
      OrderedDictionary dict = new OrderedDictionary();
      dict.Add("A", "Laptop");
      dict.Add("B", "Desktop");
      Console.WriteLine("Elements...");
      IDictionaryEnumerator demoEnum = dict.GetEnumerator();
      while (demoEnum.MoveNext()) {
         Console.WriteLine("Key = " + demoEnum.Key + ", Value = " + demoEnum.Value);
      }
      dict.Add("C", "Ultrabook");
      dict.Add("D", "Alienware");
      Console.WriteLine("\nElements...UPDATED");
      demoEnum = dict.GetEnumerator();
      while (demoEnum.MoveNext()) {
         Console.WriteLine("Key = " + demoEnum.Key + ", Value = " + demoEnum.Value);
      }
      dict.Insert(2, "K", "Speakers");
      Console.WriteLine("\nElements...UPDATED");
      demoEnum = dict.GetEnumerator();
      while (demoEnum.MoveNext()) {
         Console.WriteLine("Key = " + demoEnum.Key + ", Value = " + demoEnum.Value);
      }
   }
}

The output of the above code is −

Elements...
Key = A, Value = Laptop
Key = B, Value = Desktop

Elements...UPDATED
Key = A, Value = Laptop
Key = B, Value = Desktop
Key = C, Value = Ultrabook
Key = D, Value = Alienware

Elements...UPDATED
Key = A, Value = Laptop
Key = B, Value = Desktop
Key = K, Value = Speakers
Key = C, Value = Ultrabook
Key = D, Value = Alienware

Key Points

• The Insert method maintains the order of existing elements by shifting them to higher indices.

• The index parameter is zero-based, so index 0 represents the first position.

• If the specified index is equal to the count of elements, the entry is added at the end.

• An ArgumentOutOfRangeException is thrown if the index is less than zero or greater than the count.

Conclusion

The Insert method in OrderedDictionary allows you to add key-value pairs at specific positions while preserving the order of existing elements. This method is useful when you need to maintain a specific sequence of entries in your collection.