How to check whether 2 DirectoryInfo objects are pointing to the same directory?

Question

I have 2 DirectoryInfo objects and want to check if they are pointing to the same directory. Besides comparing their Fullname, are there any other better ways to do this? Please disregard the case of links.

Here's what I have.

DirectoryInfo di1 = new DirectoryInfo(@"c:\temp");
DirectoryInfo di2 = new DirectoryInfo(@"C:\TEMP");

if (di1.FullName.ToUpperInvariant() == di2.FullName.ToUpperInvariant())
{ // they are the same
   ...   
}

Thanks.

Answer 1

Under Linux you could compare the INode numbers of the two files wheather they are identical. But under Windows there is no such concept, at least not that I know off. You would need to use p/invoke to resolve the links if any.

Comparing strings is the best you can do. Note that using String.Compare(str1, str2, StringComparison.InvariantCultureIgnoreCase) is a bit faster than you approach.

Answer 2

On Windows Vista I could not create two folders/directories in the same path where the only difference in the names was letter-casing.

Using your code : if I called this :

di1.Create();
di2.Create();

No error would be thrown, but the result would be only one directory named C:\temp

This :

di1.Create();

followed by :

if(di2.Exists) Console.WriteLine("di2 exists");

Would print 'di2 exists' to the console window. Code fragments tested in .NET 3.0 and .NET 2.0

Answer 3

Case-insensitive comparison is the best you can get. Extract it to a helper class just in case mankind comes up with a better method.

public static class DirectoryInfoExtensions
{
    public static bool IsEqualTo(this DirectoryInfo left, DirectoryInfo right)
    {
        return left.FullName.ToUpperInvariant() == right.FullName.ToUpperInvariant();
    }
}

and use:

if (di1.IsEqualTo(di2))
{
    // Code here
}

Answer 4

You can use Uri objects instead. However, your Uri objects must point to a "file" inside these directories. That file doesn't actually have to exist.

    private void CompareStrings()
    {
        string path1 = @"c:\test\rootpath";
        string path2 = @"C:\TEST\..\TEST\ROOTPATH";
        string path3 = @"C:\TeSt\RoOtPaTh\";

        string file1 = Path.Combine(path1, "log.txt");
        string file2 = Path.Combine(path2, "log.txt");
        string file3 = Path.Combine(path3, "log.txt");

        Uri u1 = new Uri(file1);
        Uri u2 = new Uri(file2);
        Uri u3 = new Uri(file3);

        Trace.WriteLine(string.Format("u1 == u2 ? {0}", u1 == u2));
        Trace.WriteLine(string.Format("u2 == u3 ? {0}", u2 == u3));

    }

This will print out:

u1 == u2 ? True
u2 == u3 ? True