What is the right way to compare two filenames to see if they are the same file?

Question

So I have two Windows filenames I need to compare to determine if they are the same. One the user gave me, one given to me by another program. So how should you compare:

C:\Program Files\Application1\APP.EXE
C:\Progra~1\Applic~1\APP.EXE
C:\program files\applic~1\app.exe

I can't seem to find a way to consistently 'normalize' the path, I tried using Path.GetFullPath(path) and new FileInfo(path).FullName and neither seem to resolve this.

UPDATE:

Path.GetFullPath(path) will correct the short to long name conversion but it will not normalize case. Thus a StringComparer.OrdinalIgnoreCase.Equals(path1, path2) is required.

Answer 1

Harder than it ought to be. See http://stackoverflow.com/questions/684684 and http://stackoverflow.com/questions/562701.

Answer 2

You will need Path.GetFullPath() + case insensitive string comparison.

Running the following code:

using System;
using System.IO;

class Test {
 static void Main ()
 {
  //string [] str = new string[] {@"c:\program files\vim\vim72", @"c:\progra~1\vim\vim72"};
  string [] str = new string[] {@"c:\program files\Refere~1\microsoft", @"c:\progra~1\Refere~1\microsoft"};
  foreach (string s in str) {
   // Call s = Environment.ExpandEnvironmentVariables (s) if needed.
   Console.WriteLine (Path.GetFullPath (s));
  }
 }
}

gives:

c:\program files\Reference Assemblies\microsoft
c:\Program Files\Reference Assemblies\microsoft

Answer 3

a short test run says that the below code will work for the paths given:

bool CompareFileName(string file1, string file2)
        {
            var directory1 = Path.GetDirectoryName(file1);
            var directory2 = Path.GetDirectoryName(file2);
            var fileName1 = Path.GetFileName(file1);
            var fileName2 = Path.GetFileName(file2);

            return directory1.Equals(directory2, StringComparison.InvariantCultureIgnoreCase) &&
                   fileName1.Equals(fileName2, StringComparison.InvariantCultureIgnoreCase);
        }

this assumes windows platform (an assumption made due to the windows centric paths given as example paths)

Answer 4

It is simple for 99.9% of the cases:

public static bool PathsAreEquivalent(string path1, string path2)
{
    path1 = path1.ToLower();
    path2 = path2.ToLower();
    return(System.IO.Path.GetFullPath(path1) == System.IO.Path.GetFullPath(path2));
}

It doesn't take symbolic links into accound and might not work under Unix but it works for all the rest.

Answer 5

I use the FileInfo object. If you create a fileinfo object of a file that actually exists the Directory property gives a nicely formatted path name.

You also get the additional benefit of being able to test if the file actually exists.