README.md

NaturalStringExtensions

Micro-library for sorting strings using natural sort order i.e. Alphabetical order for humans.

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Background

A common scenario in many applications is ordering of string data using natural sort order.

Natural sort order is an ordering of strings in alphabetical order, except that multi-digit numbers are treated atomically, i.e., as if they were a single character. Natural sort order has been promoted as being more human-friendly ("natural") than the machine-oriented pure alphabetical order.

For example, in alphabetical sorting Folder11 would be sorted before Folder2 because 1 is sorted as smaller than 2, while in natural sorting Folder2 is sorted before Folder11 because 2 is sorted as smaller than 11.

Alphabetical	Natural		Alphabetical	Natural
Folder1	Folder1		v1.2.0	v1.2.0
Folder10 ❌	Folder2		v10.1.0 ❌	v2.0.0
Folder11 ❌	Folder10 ✅		v10.5.3 ❌	v2.1.0
Folder2	Folder11 ✅		v2.0.0	v3.1.0
Folder20	Folder20		v2.1.0	v10.1.0 ✅
Folder35	Folder35		v3.1.0	v10.5.3 ✅

Example scenarios where NaturalStringExtensions can be useful include sorting of file names, folder names, and version numbers.

Getting started 🚀

Install the NaturalStringExtensions package from NuGet:

Install-Package NaturalStringExtensions

Use one of the IEnumerable<T> extension methods to sort a list based on a string field, using natural sort order:

var folderNames = new[]
{
    "Folder20",
    "Folder1",
    "Folder2",
    "Folder10",
};

var sortedfolderNames = folderNames.OrderByNatural();

foreach (var folderName in sortedfolderNames)
{
    Console.WriteLine(folderName);
}

Output:

Folder1
Folder2
Folder10
Folder20

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In the sample folder, there's an example of a Console application that uses NaturalStringExtensions to order a list of versions using natural sort order, as described above.

Extension methods

Use one of the IEnumerable<T> extension methods to sort a list based on a string field, using a natural sort order:

Extension method	Description
OrderByNatural	Sorts the elements of a sequence in natural ascending order
OrderByNaturalDescending	Sorts the elements of a sequence in natural descending order
ThenByNatural	Performs a subsequent ordering of the elements in a sequence in natural ascending order
ThenByNaturalDescending	Performs a subsequent ordering of the elements in a sequence in natural descending order

NaturalStringComparer

A NaturalStringComparer class that implements IComparer<string> is available for comparing strings using a natural sort order:

const string left = "Folder 10";
const string right = "Folder 5";

var result = new NaturalStringComparer().Compare(left, right);
// 1 -> "Folder 10" is > "Folder 5"

For convenience, the NaturalStringComparer class has a static property called Instance with a thread-safe instance of NaturalStringComparer ready for use, which is also cached upon first use.

using System.IO;
// ...

var currentDirectory = new DirectoryInfo(Directory.GetCurrentDirectory());

var sortedDirectoryNames = currentDirectory.EnumerateDirectories()
    .OrderBy(d => d.FullName, NaturalStringComparer.Ordinal);

Sorting Arrays without LINQ

var folderNames = new[]
{
    "Folder1000",
    "Folder200",
    "Folder30",
    "Folder4",
};

Array.Sort(folderNames, NaturalStringComparer.Ordinal);

// Contents of folderNames array:
//
// Folder4
// Folder30
// Folder200
// Folder1000
//

Release History

Click on the Releases tab on GitHub.

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Copyright © 2021-2023 C. Augusto Proiete & Contributors - Provided under the Apache License, Version 2.0. NaturalStringExtensions logo is a derivative of work by Benjamin STAWARZ (original).