Natural Sort Alpha-numeric like Windows Explorer in C#

Question

I am looking for a natural sort technique like Windows explorer does.

For example, if I have the Alpha-numeric Array -

var array = new[]{"B01 002", "B01 0010", "01", "B01 001", "B10 001", "B01 01", "1", "B1 001", "B02 001", "A1"};

I am expecting this to be sorted in the below Order-
[01, 1, A1, B01 001, B01 01, B01 002, B01 0010, B1 001, B02 001, B10 001]

This is precisely the way that Windows Explorer does it-

I have tried the solutions in the below thread-

Natural Sort Order in C# - The accepted solution does the trick, but I am not allowed to use "shlwapi.dll" in my case. The rest of the answers do not sort right for the strings starting with char 'B' in the above example.
Natural sort order in C# - implementation - Sort order is not as expected.
Natural Sorting in C# & naturalstringcomparer.cs - I tried the approaches in these articles as well, but even these don't sort right.

No other constraint on the approach taken. Either it is LINQ, Regex, Extention, or Interface approach that can be used to replicate the sort order done by "shlwapi.dll"

It's in Japanese, but maybe you can use this article and the source code. [C# 自然順で文字列をソートする](https://qiita.com/tomochan154/items/1a3048f2cd9755233b4f), [toy-box/NaturalComparer.cs](https://github.com/ryosuke-ninomiya/toy-box/blob/master/NaturalComparer.cs) — kunif, Sep 09 '22 at 07:36
Does this solution not work? https://stackoverflow.com/a/66354540/14868997 — Charlieface, Sep 09 '22 at 09:12
See https://dotnetfiddle.net/q9aWDI it looks exactly the same as you requested — Charlieface, Sep 09 '22 at 09:17
Does this answer your question? [Natural Sort Order in C#](https://stackoverflow.com/questions/248603/natural-sort-order-in-c-sharp) — Charlieface, Sep 11 '22 at 01:58

Dmitry Bychenko · Accepted Answer · 2022-09-09T07:28:58.397

I suggest splitting string to chunks where each chunk is either all digits or no digits: "B01 001" -> {"B", "01", " ", "001"}. Then compare these chunks (comparing two all digits chunks being a special case).

Code: (Fiddle)

public sealed class NaturalComparer : IComparer<string> {

  private static int CompareChunks(string x, string y) {
    if (x[0] >= '0' && x[0] <= '9' && y[0] >= '0' && y[0] <= '9') {
      string tx = x.TrimStart('0');
      string ty = y.TrimStart('0');

      int result = tx.Length.CompareTo(ty.Length);

      if (result != 0)
        return result;

      result = tx.CompareTo(ty);

      if (result != 0)
        return result;
    }
    
    return string.Compare(x, y);
  }

  public int Compare(string? x, string? y) {
    if (ReferenceEquals(x, y))
      return 0;
    if (x is null)
      return -1;
    if (y is null)
      return +1;

    var itemsX = Regex
      .Split(x, "([0-9]+)")
      .Where(item => !string.IsNullOrEmpty(item))
      .ToList();

    var itemsY = Regex
      .Split(y, "([0-9]+)")
      .Where(item => !string.IsNullOrEmpty(item))
      .ToList();

    for (int i = 0; i < Math.Min(itemsX.Count, itemsY.Count); ++i) {
      int result = CompareChunks(itemsX[i], itemsY[i]);

      if (result != 0)
        return result;
    }

    return itemsX.Count.CompareTo(itemsY.Count);
  }
}

Demo:

string[] demo = new string[] {
    "B01 002", 
    "B01 0010", 
    "01", 
    "B01 001", 
    "B10 001", 
    "B01 01", 
    "1", 
    "B1 001", 
    "B02 001", 
    "A1"
};

Array.Sort(demo, new NaturalComparer());

Console.WriteLine(string.Join(Environment.NewLine, demo));

Output:

Natural Sort Alpha-numeric like Windows Explorer in C#

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