---
title: "SortedList in C#"  
description: "The SortedList offer more flexibility by allowing access to the variables either through the associated keys or through the indexes."  
author: "Anupam Mishra"  
published: 2016-01-01  
updated: 2019-10-28  
canonical: https://www.mindstick.com/articles/11976/sortedlist-in-c-sharp  
category: "c#"  
tags: ["c#", "collection"]  
reading_time: 3 minutes  

---

# SortedList in C#

[SortedList](https://answers.mindstick.com/qa/93937/what-is-the-role-of-sortedlist-k-v-in-c-sharp-and-why-are-use-this-collection-in-c-sharp-explain-with-example) internally maintain [two arrays](https://www.mindstick.com/forum/156673/merge-two-arrays-in-jquery) to store the [elements](https://www.mindstick.com/forum/1440/wpf-button-with-multiple-text-elements) of the list, i.e. one array maintain a keys and another one storing associated values. Each element is a key/value pair that can be accessed as a DictionaryEntry object. In SortedList a key cannot be null, but a value can be. A SortedList elements can be accessed by its key, like an element in any IDictionary [implementation](https://answers.mindstick.com/qa/44913/who-is-the-minister-of-statistics-and-programme-implementation), or by its index, like an element in any IList implementation.

The capacity of SortedList object is depends upon its element but by default capacity is 16. When elements are added to the SortedList, the capacity is automatically increased as [required](https://yourviews.mindstick.com/view/81031/vigilence-required-during-corona-pandemic) through reallocation. You can decrease the capacity of your SortedList by calling TrimToSize or by setting the Capacity [property](https://www.mindstick.com/articles/198559/an-ownership-of-property-in-hua-hin) explicitly.

The index sequence is based on the sort sequence. When an element is added to SortedList, It is set correct sort order and the [indexing](https://www.mindstick.com/blog/303693/how-search-engines-work-crawling-indexing-and-ranking) adjust accordingly. Therefore, the index of a specific key/value pair in SortedList might change as elements are added or removed from the SortedList object.

In SortedList objects tends to be slower than [operations](https://www.mindstick.com/news/2675/bmw-agrees-to-integrate-blockchain-with-operations-partners-with-bnb-chain-coinweb) on a Hashtable because of sorting.

However, the SortedList offer more flexibility by allowing access to the [variables](https://www.mindstick.com/articles/715/php-variables) either through the associated keys or through the indexes.

##### Creating a SortedList:

```
SortedList sl = new SortedList();
// Adding elements in the SortedList
            sl.Add("1", "One");
            sl.Add("10", "Ten");
            sl.Add("3", "Three");

//Retrieving elements to the SortedList
            ICollection key = sl.Keys;
            foreach (var n in key)
            {
                Console.WriteLine(n+": "+sl[n]);
            }
```

Output: 1: One 10: Ten 3: Three

##### \

##### For checking the capacity of SortedList use Capacity properties i.e. follows:

> ```
>   Console.WriteLine (“Counts
> number of elements:  {0}”, sl.Count);//For checking capacity you can use sl.Capacity property.        //
> Fethching values by index            Console.WriteLine("{0}", sl.GetByIndex(1));        //
> Fethching key by index           Console.WriteLine("{0}", sl.GetKey(1));
> ```

Advantage:

1. It boots performance for lookups because its uses internally binary search algorithm.

2. It may requires low memory for storage.

3. It performs well on small data sets.

For example, we create an [instance](https://www.mindstick.com/forum/155658/testing-connection-to-cloud-sql-instance-with-a-mysql-client-from-vm-instance) of SortedList and adding three elements in it. Then we are retrieving all elements in the SortedList and performs various operations using its methods.

```
using System;using System.Collections;namespace SortedListEx{    class Program    {        static void Main(string[] args)        {            //Creating SortedList            SortedList sl = new SortedList();            sl.Add("1", "One");            sl.Add("10", "Ten");            sl.Add("3", "Three");            // Fethching all elements            ICollection key = sl.Keys;            Console.WriteLine("Retrieving all elements in the SortedList:");            Console.WriteLine();            foreach (var n in key)            {                Console.WriteLine(n+":"+sl[n]);            }            Console.WriteLine();             if (sl.ContainsValue("Two"))            {                Console.WriteLine("Two is already exists");            }            else            {                Console.WriteLine();                Console.WriteLine("Adding 'Two' in sorted List");                sl.Add("2", "Two");            }            Console.WriteLine();            Console.WriteLine("Number of Elemnts: "+sl.Count);            Console.WriteLine();            Console.WriteLine("Capacity: " + sl.Capacity);            Console.WriteLine();            int k = 1;            Console.WriteLine("Fetching values passing index {0}", sl.GetByIndex(k));            Console.WriteLine();            // Fethching Key by passing index            Console.WriteLine("Fetching Key by passing index: {0}"   , sl.GetKey(k));            Console.ReadLine();        }    }}
```

##### Output:

![SortedList in C#](https://www.mindstick.com/mindstickarticle/f67d6c99-b64d-41aa-955b-17a2018bf9f7/images/d2d8eb7a-e62a-4e58-af91-024a148eb8b3.png)**\**

---

Original Source: https://www.mindstick.com/articles/11976/sortedlist-in-c-sharp

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