using System;

using System.IO;

public class Program

{

    public static void Main()

    {

        Console.WriteLine($"Path.DirectorySeparatorChar: '{Path.DirectorySeparatorChar}'");

        Console.WriteLine($"Path.AltDirectorySeparatorChar: '{Path.AltDirectorySeparatorChar}'");

        Console.WriteLine($"Path.PathSeparator: '{Path.PathSeparator}'");

        Console.WriteLine($"Path.VolumeSeparatorChar: '{Path.VolumeSeparatorChar}'");

​

        Console.WriteLine();

        string itemPath = @"C:\RootFolder\SubFolder\MoreSubFolder\LastFolder\SomeFile.txt";

        string baseDirectory = @"C:\RootFolder\SubFolder\";

​

        string result = System.IO.Path.GetRelativePath(baseDirectory, itemPath);

        Console.WriteLine(result);

​

        // because Dotnet Fiddle is hosted on a linux runtime, we need to replace the directory separator, we could hardcode '/' instead

        Console.WriteLine($"Adjusted to because host environment doesn't recognise \\ as Path.DirectorySeparatorChar");

        string resultFixed = System.IO.Path.GetRelativePath(baseDirectory.Replace('\\',Path.DirectorySeparatorChar), itemPath.Replace('\\',Path.DirectorySeparatorChar)).Replace(Path.DirectorySeparatorChar,'\\');

​

        Console.WriteLine(resultFixed);

​

    }

}