How to sort a list in C#?

Sorting a list in C# can be accomplished using several methods. The List<T> class provides the Sort() method for in-place sorting, while LINQ offers additional sorting capabilities. This article demonstrates various approaches to sort lists in ascending and descending order.

Syntax

Following is the syntax for the basic Sort() method −

list.Sort();

Following is the syntax for sorting with a custom comparer −

list.Sort((x, y) => y.CompareTo(x)); // descending order

Using List.Sort() Method

The Sort() method sorts the elements in the entire list using the default comparer for the list element type. This method modifies the original list −

Example

using System;
using System.Collections.Generic;

public class Program {
   public static void Main() {
      var cars = new List<string>() {"Mercedes", "Audi", "Jaguar"};
      Console.WriteLine("Original List:");
      foreach (var name in cars) {
         Console.WriteLine(name);
      }
      
      // sort in ascending order
      cars.Sort();
      Console.WriteLine("\nSorted List (Ascending):");
      foreach (var name in cars) {
         Console.WriteLine(name);
      }
   }
}

The output of the above code is −

Original List:
Mercedes
Audi
Jaguar

Sorted List (Ascending):
Audi
Jaguar
Mercedes

Sorting in Descending Order

To sort a list in descending order, you can use a custom comparer or the Reverse() method after sorting −

Example

using System;
using System.Collections.Generic;

public class Program {
   public static void Main() {
      var numbers = new List<int>() {45, 12, 78, 23, 67};
      Console.WriteLine("Original List:");
      foreach (var num in numbers) {
         Console.Write(num + " ");
      }
      
      // sort in descending order using custom comparer
      numbers.Sort((x, y) => y.CompareTo(x));
      Console.WriteLine("<br>\nSorted List (Descending):");
      foreach (var num in numbers) {
         Console.Write(num + " ");
      }
   }
}

The output of the above code is −

Original List:
45 12 78 23 67 

Sorted List (Descending):
78 67 45 23 12 

Using LINQ OrderBy() Method

LINQ's OrderBy() method creates a new sorted sequence without modifying the original list. This is useful when you want to preserve the original list −

Example

using System;
using System.Collections.Generic;
using System.Linq;

public class Program {
   public static void Main() {
      var fruits = new List<string>() {"Banana", "Apple", "Orange", "Cherry"};
      Console.WriteLine("Original List:");
      foreach (var fruit in fruits) {
         Console.WriteLine(fruit);
      }
      
      // create sorted sequence using LINQ
      var sortedFruits = fruits.OrderBy(x => x).ToList();
      Console.WriteLine("\nSorted using LINQ OrderBy:");
      foreach (var fruit in sortedFruits) {
         Console.WriteLine(fruit);
      }
      
      // original list remains unchanged
      Console.WriteLine("\nOriginal list after LINQ sort:");
      foreach (var fruit in fruits) {
         Console.WriteLine(fruit);
      }
   }
}

The output of the above code is −

Original List:
Banana
Apple
Orange
Cherry

Sorted using LINQ OrderBy:
Apple
Banana
Cherry
Orange

Original list after LINQ sort:
Banana
Apple
Orange
Cherry

Comparison of Sorting Methods

Conclusion

C# provides multiple ways to sort lists: List.Sort() for in-place sorting, custom comparers for descending order, and LINQ OrderBy() for creating new sorted sequences. Choose Sort() for performance when modifying the original list is acceptable, or use LINQ when you need to preserve the original data.