In c#,SortedList is a generic type of collection used to store a collection of key/value pairs that are sorted by key based on the associatedIComparer<T> implementation.

By default, the sortedlist will sort key/value pairs in ascending order of the key, and the sortedlist will allow storing only the strongly-typed objects, i.e., the key/value pairs of the specifieddata type.

In c#, the sortedlist will allow us to store duplicate values, but the keys must be unique and cannot be null to identify the values in sortedlist. The size of sortedlist will vary dynamically so that you can add or remove elements from the sortedlist based on our application requirements.

C# SortedList Declaration

In c#, sortedlist is a generic type ofcollection, and it is provided bySystem.Collections.Generic namespace.

As discussed, the collection is aclass, so to define a sortedlist, you need to declare an instance of the sortedlist class before we perform any operations like add, delete, etc. like as shown below.

If you observe the above sortedlist declaration, we created a generic sortedlist (slst) with an instance of sortedlist class using type parameters (TKey,TValue) as placeholders with an angle (<>) brackets.

Here, the angle (<>) brackets will indicate that the sortedlist is ageneric type and type parameterTKey represents a type of keys to be accepted by sortedlist, andTValue is used to represent a type of values to be accepted by sortedlist.

C# SortedList Initialization

Following is the example of initializing a generic sortedlist by specifying a required type for key and value.

If you observe the above example, we defined a sortedlist (slist) with the required key and value types to store. Here, the sortedlist will store a key ofstring type and value ofint type.

Internally, the sortedlist will maintain two objects[]arrays, one forkeys and another forvalues. When we add key/value pair, it will perform a binary search using the key to find an appropriate index to store a key and value in respective arrays.

C# SortedList Properties

The following are some of the commonly usedproperties of generic sortedlist in c# programming language.

C# SortedList Methods

The following are some of the commonly usedmethods of generic sortedlist to perform add, search, insert, delete or sort operations in the c# programming language.

C# Add Elements to SortedList

In c#, while adding elements to sortedlist, we need to make sure that there will not be any duplicate keys because sortedlist will allow us to store duplicate values, but keys must be unique to identify the values in the list.

Following is the example of adding key/value pair elements to a sorted list in different ways.

If you observe the above example, we are able to define a new generic sortedlist (slst,slst2) collections by usingSystem.Collections.Generic namespace. Here, we added only the defineddata type keys and values to the newly created lists (slst,slst2) in different ways.

As discussed, the Add method will throw an exception if we try to add a key (2) that is already existing, so to handle that exception, we used atry-catch block.

When you execute the above c# program, we will get the result as shown below.

If you observe the above result, by default all the list elements are sorted in ascending order based on the key, and we got an exception when we tried to add a key (2) that is already existing and added a key (5) which is not existing in the list.

C# Access SortedList Elements

In c#, we have different ways to access sorted list elements, i.e., either using index positions or by iterating through the list usingfor /foreach loops.

Following is the example of accessing the sortedlist elements in different ways.

If you observe the above example, we are accessing generic list elements in different ways by using index positions for and foreach loops based on our requirements.

When you execute the above c# program, we will get the result as shown below.

C# Remove Elements from SortedList

In c#, we have different methods to remove elements from the sorted list, i.e., either usingRemove() orRemoveAt() methods.

Following is the example of deleting elements from the sorted list in the c# programming language.

If you observe the above example, we used aRemove() method to delete a particular key of elements from the list. We used aRemoveAt() method to delete an element at a specified index position.

When you execute the above c# program, you will get the result as shown below.

If you want to remove all the elements from the sorted list, then use the Clear() method.

C# SortedList Check If Item Exists

By usingContainsKey() andContainsValue() methods, you can check whether the specified element exists in a sorted list or not. If it exists, these methods will returntrue otherwisefalse.

Following is the example of usingContainsKey() andContainsValue() methods to check for an item that exists in a sorted list or not in c#.

If you observe the above example, we used aContainsKey() andContainsValue() methods to check for particular keys and values that exist in the sorted list (slst) or not.

When you execute the above c# program, we will get the result as shown below.

C# SortedList (SortedList<TKey, TValue>) Overview

The following are the important points that need to remember about the sorted list in c#.

• SortedList is used to store a collection of key/value pairs sorted by key based on the associatedIComparer<T> implementation.
• SortedList will allow us to store duplicate values, but keys must be unique to identify the values in the sorted list.
• In SortedList, the keys cannot be null, but the values can be null.
• You can access SortedList elements either by using keys, index positions, or withfor andforeach loops. In the foreach loop, we need to useKeyValuePair<TKey, TValue> to get key/value pairs from SortedList.