Remove the element with the specified key from a SortedList in C#

The SortedList class in C# provides the Remove() method to remove an element with a specified key. When you remove an element, the SortedList automatically adjusts its internal structure to maintain the sorted order of the remaining elements.

Syntax

Following is the syntax for removing an element from a SortedList −

sortedList.Remove(key);

Parameters

• key: The key of the element to remove from the SortedList.

Using Remove() with String Keys

This example demonstrates removing an element with a string key from a SortedList −

using System;
using System.Collections;

public class Demo {
   public static void Main(String[] args) {
      SortedList sortedList = new SortedList();
      sortedList.Add("A", "1");
      sortedList.Add("B", "2");
      sortedList.Add("C", "3");
      sortedList.Add("D", "4");
      sortedList.Add("E", "5");
      sortedList.Add("F", "6");
      sortedList.Add("G", "7");
      sortedList.Add("H", "8");
      sortedList.Add("I", "9");
      sortedList.Add("J", "10");

      Console.WriteLine("SortedList elements...");
      foreach(DictionaryEntry d in sortedList) {
         Console.WriteLine("Key = " + d.Key + ", Value = " + d.Value);
      }
      Console.WriteLine("Count of SortedList key-value pairs = " + sortedList.Count);

      sortedList.Remove("H");

      Console.WriteLine("\nEnumerator to iterate through the SortedList...");
      IDictionaryEnumerator demoEnum = sortedList.GetEnumerator();
      while (demoEnum.MoveNext())
         Console.WriteLine("Key = " + demoEnum.Key + ", Value = " + demoEnum.Value);
      Console.WriteLine("Count of SortedList key-value pairs (Updated) = " + sortedList.Count);
   }
}

The output of the above code is −

SortedList elements...
Key = A, Value = 1
Key = B, Value = 2
Key = C, Value = 3
Key = D, Value = 4
Key = E, Value = 5
Key = F, Value = 6
Key = G, Value = 7
Key = H, Value = 8
Key = I, Value = 9
Key = J, Value = 10
Count of SortedList key-value pairs = 10

Enumerator to iterate through the SortedList...
Key = A, Value = 1
Key = B, Value = 2
Key = C, Value = 3
Key = D, Value = 4
Key = E, Value = 5
Key = F, Value = 6
Key = G, Value = 7
Key = I, Value = 9
Key = J, Value = 10
Count of SortedList key-value pairs (Updated) = 9

Using Remove() with Word Keys

This example shows removing an element where both keys and values are meaningful strings −

using System;
using System.Collections;

public class Demo {
   public static void Main(String[] args) {
      SortedList sortedList = new SortedList();
      sortedList.Add("One", "Mouse");
      sortedList.Add("Two", "Keyboard");
      sortedList.Add("Three", "Headphone");
      sortedList.Add("Four", "Speakers");
      sortedList.Add("Five", "RAM");

      Console.WriteLine("SortedList elements...");
      foreach(DictionaryEntry d in sortedList) {
         Console.WriteLine("Key = " + d.Key + ", Value = " + d.Value);
      }
      Console.WriteLine("Count of SortedList key-value pairs = " + sortedList.Count);

      sortedList.Remove("Three");

      Console.WriteLine("\nEnumerator to iterate through the SortedList...");
      IDictionaryEnumerator demoEnum = sortedList.GetEnumerator();
      while (demoEnum.MoveNext())
         Console.WriteLine("Key = " + demoEnum.Key + ", Value = " + demoEnum.Value);
      Console.WriteLine("Count of SortedList key-value pairs (Updated) = " + sortedList.Count);
   }
}

The output of the above code is −

SortedList elements...
Key = Five, Value = RAM
Key = Four, Value = Speakers
Key = One, Value = Mouse
Key = Three, Value = Headphone
Key = Two, Value = Keyboard
Count of SortedList key-value pairs = 5

Enumerator to iterate through the SortedList...
Key = Five, Value = RAM
Key = Four, Value = Speakers
Key = One, Value = Mouse
Key = Two, Value = Keyboard
Count of SortedList key-value pairs (Updated) = 4

How It Works

When you call Remove() on a SortedList:

• The method searches for the specified key in the sorted collection.

• If the key is found, both the key and its associated value are removed.

• The remaining elements automatically shift to maintain the sorted order.

• The Count property is decremented by one.

Conclusion

The Remove() method in C# SortedList efficiently removes an element by its key while maintaining the sorted order of remaining elements. This operation automatically updates the collection's count and ensures the internal structure remains consistent.