Are there C# methods to get the number of folders up or down from a reference path?

Question

I am looking for a simple API set of methods that find out if a folder is a subdirectory of another folder, and how many steps there are between this. Something like:

int numberOfFoldersDown(string parentFolder, string subfolder)  { ... }

It seems quite useful, though tedious to write, so I thought it should be somewhere in the System.IO.Path or System.IO.Directory assemblies, but I can't find any helpful methods there. Are these functions available, or should I write them myself?

Answer 1

Nothing built-in AFAIK.

Here's some recursive example that uses both Path and Directory methods:

internal class Program
{
    private static void Main(string[] args)
    {
        Console.WriteLine(NumberOfFoldersDown(@"c:\temp\", @"c:\temp\"));                   // 0
        Console.WriteLine(NumberOfFoldersDown(@"c:\temp\", @"c:\temp\zz\"));                // 1
        Console.WriteLine(NumberOfFoldersDown(@"c:\temp2\", @"c:\temp\zz\"));               // -1
        Console.WriteLine(NumberOfFoldersDown(@"c:\temp2\", @"c:\temp2\zz\hui\55\"));       // 3
        Console.WriteLine(NumberOfFoldersDown(@"c:\temp2\zz\", @"c:\temp2\zz\hui\55\"));    // 2

        Console.Read();
    }

    public static int NumberOfFoldersDown(string parentFolder, string subfolder)
    {
        int depth = 0;
        WalkTree(parentFolder, subfolder, ref depth);
        return depth;
    }

    public static void WalkTree(string parentFolder, string subfolder, ref int depth)
    {
        var parent = Directory.GetParent(subfolder);
        if (parent == null)
        {
            // Root directory and no match yet
            depth = -1;
        }
        else if (0 != string.Compare(Path.GetFullPath(parentFolder).TrimEnd('\\'), Path.GetFullPath(parent.FullName).TrimEnd('\\'), true))
        {
            // No match yet, continue recursion
            depth++;
            WalkTree(parentFolder, parent.FullName, ref depth);
        }
    }
}