How can I compare (directory) paths in C#?

GetFullPath seems to do the work, except for case difference (Path.GetFullPath("test") != Path.GetFullPath("TEST")) and trailing slash. So, the following code should work fine:

String.Compare(
    Path.GetFullPath(path1).TrimEnd('\\'),
    Path.GetFullPath(path2).TrimEnd('\\'), 
    StringComparison.InvariantCultureIgnoreCase)

Or, if you want to start with DirectoryInfo:

String.Compare(
    dirinfo1.FullName.TrimEnd('\\'),
    dirinfo2.FullName.TrimEnd('\\'), 
    StringComparison.InvariantCultureIgnoreCase)

There are some short comes to the implementation of paths in .NET. There are many complaints about it. Patrick Smacchia, the creator of NDepend, published an open source library that enables handling of common and complex path operations. If you do a lot of compare operations on paths in your application, this library might be useful to you.

It seems that P/Invoking GetFinalPathNameByHandle() would be the most reliable solution.

UPD: Oops, I didn't take into account your desire not to use any I/O

 System.IO.Path.GetFullPath(pathA).Equals(System.IO.Path.GetFullPath(PathB));

The "Name" properties are equal. Take:

DirectoryInfo dir1 = new DirectoryInfo("C:\\Scratch");
DirectoryInfo dir2 = new DirectoryInfo("C:\\Scratch\\");
DirectoryInfo dir3 = new DirectoryInfo("C:\\Scratch\\4760");
DirectoryInfo dir4 = new DirectoryInfo("C:\\Scratch\\4760\\..\\");

dir1.Name == dir2.Name and dir2.Name == dir4.Name ("Scratch" in this case. dir3 == "4760".) It's only the FullName properties that are different.

You might be able to do a recursive method to examine the Name properties of each parent given your two DirectoryInfo classes to ensure the complete path is the same.

EDIT: does this work for your situation? Create a Console Application and paste this over the entire Program.cs file. Provide two DirectoryInfo objects to the AreEquals() function and it will return True if they're the same directory. You might be able to tweak this AreEquals() method to be an extension method on DirectoryInfo if you like, so you could just do myDirectoryInfo.IsEquals(myOtherDirectoryInfo);

using System;
using System.Diagnostics;
using System.IO;
using System.Collections.Generic;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(AreEqual(
                new DirectoryInfo("C:\\Scratch"),
                new DirectoryInfo("C:\\Scratch\\")));

            Console.WriteLine(AreEqual(
                new DirectoryInfo("C:\\Windows\\Microsoft.NET\\Framework"),
                new DirectoryInfo("C:\\Windows\\Microsoft.NET\\Framework\\v3.5\\1033\\..\\..")));

            Console.WriteLine(AreEqual(
                new DirectoryInfo("C:\\Scratch\\"),
                new DirectoryInfo("C:\\Scratch\\4760\\..\\..")));

            Console.WriteLine("Press ENTER to continue");
            Console.ReadLine();
        }

        private static bool AreEqual(DirectoryInfo dir1, DirectoryInfo dir2)
        {
            DirectoryInfo parent1 = dir1;
            DirectoryInfo parent2 = dir2;

            /* Build a list of parents */
            List<string> folder1Parents = new List<string>();
            List<string> folder2Parents = new List<string>();

            while (parent1 != null)
            {
                folder1Parents.Add(parent1.Name);
                parent1 = parent1.Parent;
            }

            while (parent2 != null)
            {
                folder2Parents.Add(parent2.Name);
                parent2 = parent2.Parent;
            }

            /* Now compare the lists */

            if (folder1Parents.Count != folder2Parents.Count)
            {
                // Cannot be the same - different number of parents
                return false;
            }

            bool equal = true;

            for (int i = 0; i < folder1Parents.Count && i < folder2Parents.Count; i++)
            {
                equal &= folder1Parents[i] == folder2Parents[i];
            }

            return equal;
        }
    }
}

I used recursion to solve this problem for myself.

 public bool PathEquals(string Path1, string Path2)
 {
     FileInfo f1 = new FileInfo(Path1.Trim('\\','/','.'));
     FileInfo f2 = new FileInfo(Path2.Trim('\\', '/','.'));
     if(f1.Name.ToLower() == f2.Name.ToLower())
     {
         return DirectoryEquals(f1.Directory, f2.Directory);
     }
     else
     {
         return false;
     }
}

public bool DirectoryEquals(DirectoryInfo d1, DirectoryInfo d2)
{
    if(d1.Name.ToLower() == d2.Name.ToLower())
    {
        if((d1.Parent != null) && (d2.Parent != null))
        {
            return DirectoryEquals(d1.Parent, d2.Parent);
        }
        else
        {
            return true;//C:\Temp1\Temp2 equals \Temp1\Temp2
            //return (d1.Parent == null) && (d2.Parent == null);//C:\Temp1\Temp2 does not equal \Temp1\Temp2
        }
    }
    else
    {
        return false;
    }
}

Note: new FileInfo(path) returns a valid FileInfo even if path is not a file (the name field is equal to the directory name)

Thank you, @Andy Shellam and @VladV and @Eamon Nerbonne

I found the other solution:

        private static bool AreEqual(DirectoryInfo dir1, DirectoryInfo dir2)
        {
            return AreEqual(dir1.FullName, dir2.FullName);
        }

        private static bool AreEqual(string folderPath1, string folderPath2)
        {
            folderPath1 = Path.GetFullPath(folderPath1);
            folderPath2 = Path.GetFullPath(folderPath2);

            if (folderPath1.Length == folderPath2.Length)
            {
                return string.Equals(folderPath1, folderPath2/*, StringComparison.OrdinalIgnoreCase*/);
            }
            else if (folderPath1.Length == folderPath2.Length + 1 && IsEndWithAltDirectorySeparatorChar(folderPath1))
            {
                // folderPath1 = @"F:\temp\"
                // folderPath2 = @"F:\temp"
                return folderPath1.Contains(folderPath2 /*, StringComparison.OrdinalIgnoreCase*/);
            }
            else if (folderPath1.Length + 1 == folderPath2.Length && IsEndWithAltDirectorySeparatorChar(folderPath2))
            {
                // folderPath1 = @"F:\temp"
                // folderPath2 = @"F:\temp\"
                return folderPath2.Contains(folderPath1 /*, StringComparison.OrdinalIgnoreCase*/);
            }

            return false;

            static bool IsEndWithAltDirectorySeparatorChar(string path)
            {
                var lastChar = path[path.Length - 1];
                return lastChar == Path.DirectorySeparatorChar;
            }
        }

It can work well.

        static void Main(string[] args)
        {
            Console.WriteLine(AreEqual(
                new DirectoryInfo("C:\\Scratch"),
                new DirectoryInfo("C:\\Scratch\\")));

            Console.WriteLine(AreEqual(
                new DirectoryInfo("C:\\Windows\\Microsoft.NET\\Framework"),
                new DirectoryInfo("C:\\Windows\\Microsoft.NET\\Framework\\v3.5\\1033\\..\\..")));

            Console.WriteLine(AreEqual(
                new DirectoryInfo("C:\\Scratch\\"),
                new DirectoryInfo("C:\\Scratch\\4760\\..\\..")));

            Debug.WriteLine(AreEqual(@"C:/Temp", @"C:\Temp2")); // False
            Debug.WriteLine(AreEqual(@"C:\Temp\", @"C:\Temp2"));// False
            Debug.WriteLine(AreEqual(@"C:\Temp\", @"C:\Temp")); // True
            Debug.WriteLine(AreEqual(@"C:\Temp/", @"C:\Temp")); // True
            Debug.WriteLine(AreEqual(@"C:/Temp/", @"C:\Temp\"));// True

            Console.WriteLine("Press ENTER to continue");
            Console.ReadLine();
        }

bool equals = myDirectoryInfo1.FullName == myDirectoryInfo2.FullName;

?