C# SortedList

The SortedList class in C# is part of the System.Collections namespace and represents a collection of key-value pairs that are sorted by the keys. This tutorial will cover the following topics related to the SortedList class in C#:

Creating a SortedList
Adding elements
Accessing elements
Removing elements
Looping through a SortedList

Let's begin!

Creating a SortedList

To create a new instance of the SortedList class, use the SortedList constructor:

using System.Collections;

SortedList sortedList = new SortedList();

Adding elements

To add an element to a SortedList, use the Add method:

sortedList.Add("one", 1);
sortedList.Add("two", 2);
sortedList.Add("three", 3);

In this example, we add three key-value pairs to the SortedList. The keys are strings and the values are integers.

Accessing elements

To access an element in a SortedList by its key, use the indexer:

int value = (int)sortedList["two"];  // Cast the value to int
Console.WriteLine(value);  // Output: 2

To access a key or value by its index, use the GetKey and GetByIndex methods, respectively:

string key = (string)sortedList.GetKey(1);
int value = (int)sortedList.GetByIndex(1);
Console.WriteLine($"{key}: {value}");  // Output: two: 2

Removing elements

To remove an element from a SortedList by its key, use the Remove method:

sortedList.Remove("two");

To remove an element from a SortedList by its index, use the RemoveAt method:

sortedList.RemoveAt(1);

Looping through a SortedList

To loop through the keys and values of a SortedList, you can use a foreach loop:

foreach (DictionaryEntry entry in sortedList)
{
    Console.WriteLine($"{entry.Key}: {entry.Value}");
}

Alternatively, you can use the for loop and the Count property to iterate through the keys and values by index:

for (int i = 0; i < sortedList.Count; i++)
{
    string key = (string)sortedList.GetKey(i);
    int value = (int)sortedList.GetByIndex(i);
    Console.WriteLine($"{key}: {value}");
}

That's it! You've now learned how to use the SortedList class in C# to store and manipulate key-value pairs that are sorted by the keys. The SortedList class is useful for scenarios where you need to maintain a sorted collection of key-value pairs and have fast key-based lookups. Note that the SortedList class is not type-safe and requires casting when working with keys and values. If you need a type-safe sorted collection, consider using the SortedDictionary<TKey, TValue> class from the System.Collections.Generic namespace instead.

How to use SortedList in C#

SortedList is a collection that maintains elements in sorted order based on their keys.

using System;
using System.Collections;

class Program
{
    static void Main()
    {
        SortedList sortedList = new SortedList();
        sortedList.Add(3, "Three");
        sortedList.Add(1, "One");
        sortedList.Add(2, "Two");

        foreach (DictionaryEntry entry in sortedList)
        {
            Console.WriteLine($"{entry.Key}: {entry.Value}");
        }
    }
}

Custom sorting with IComparer in C# SortedList

Implement IComparer for custom sorting logic.

class CustomComparer : IComparer
{
    public int Compare(object x, object y)
    {
        // Custom comparison logic
    }
}

C# SortedList and LINQ queries
SortedList can be used with LINQ for various querying operations.
```
var results = sortedList.Cast<DictionaryEntry>().Where(entry => entry.Key.Equals(2));
```