Check if DirectoryInfo.FullName is special folder

Question

My goal is to check, if DirectoryInfo.FullName is one of the special folders.

Here is what I'm doing for this (Check directoryInfo.FullName to each special folder if they are equal):

        DirectoryInfo directoryInfo = new DirectoryInfo("Directory path");

        if (directoryInfo.FullName == Environment.GetFolderPath(Environment.SpecialFolder.Windows) ||
            directoryInfo.FullName == Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles ||) 
            ...
            ...
           )
        {
            // directoryInfo is the special folder
        }

But there are many special folders (Cookies, ApplicationData, InternetCache, etc.). Is there any way to do this task more efficiently?

Thanks.

Switch

Answer 1

Try this following code :

        bool result = false;
        DirectoryInfo directoryInfo = new DirectoryInfo("Directory path");
        foreach (Environment.SpecialFolder suit in Enum.GetValues(typeof(Environment.SpecialFolder)))
        {
            if (directoryInfo.FullName == Environment.GetFolderPath(suit))
            {
                result = true;
                break;
            }
        }

        if (result)
        {
            // Do what ever you want
        }

hope this help.

Arrogance

Any idea how this handles translation, writing systems and case-sensitivity? I genuinely can't tell from looking in the docs. If do try out, I'll let SO know. – Astatine

Answer 2

I'm afraid the answers given seem to be the only way, I hate the special folders because what ought to be a very simple function -

void CollectFiles(string strDir, string pattern) {
  DirectoryInfo di = new DirectoryInfo(strDir);
  foreach(FileInfo fi in di.GetFiles(pattern) {
    //store file data
  }
  foreach(DirectoryInfo diInfo in di.GetDirectories()) {
    CollectFiles(diInfo);
  }
}

Becomes ugly because you have to include

Check If This Is A Special Folder And Deal With It And Its Child Folders Differently ();

Fair enough Microsoft, to have a folder that could exist anywhere, on a remote PC, on a server etc. But really what is wrong with the UNIX/Linux way, use links to folder and if the destination physical folder has to move, alter the link. Then you can itterate them in a nice neat function treating them all as if ordinary folders.

Basinger

Answer 3

I don't have enough reputation to add a comment so as a +1 to BobRassler's answer, string comparisons might be more useful.

bool isSpecialFolder = false;
DirectoryInfo directoryInfo = new DirectoryInfo(Path.Combine(tbx_FolderName.Text, fileName));

foreach (Environment.SpecialFolder specialFolder in Enum.GetValues(typeof(Environment.SpecialFolder)))
{
    if (directoryInfo.FullName.ToString()
            .ToLower() ==
        Environment.GetFolderPath(specialFolder)
            .ToLower())
    {
        isSpecialFolder = true;
        break;
    }
}

if (isSpecialFolder)
{
    // something 
}
else
{
    // something else
}

Jahdai

Or you should call Equals with StringComparison.OrdinalIgnoreCase instead of converting both strings. That's much faster. – Oriente

Yeah, I was also wondering how this handles i18n and what happens if the languages are different (like, you get MyDocuments from a config on a different language system). And as you said, of course the whole case-aware-but-not-sensitive thing makes it more complicated to think about it :-) – Astatine

Answer 4

Use a reflection to get all values from that enum, like here http://geekswithblogs.net/shahed/archive/2006/12/06/100427.aspx and check against collection of generated paths you get.

Alimentary

The link's dead Jim. The link's dead… – Astatine

Answer 5

I ended up using it this way:

public static bool IsSpecialFolder(DirectoryInfo directoryInfo, out Environment.SpecialFolder? _specialFolder) {
    bool isSpecialFolder = false;
    _specialFolder = null;

    string directoryInfo_FullPath = directoryInfo.FullName;
    foreach (Environment.SpecialFolder specialFolder in Enum.GetValues(typeof(Environment.SpecialFolder))) {
        var specialFolder_FullPath = Environment.GetFolderPath(specialFolder);

        if (string.Equals(directoryInfo_FullPath, specialFolder_FullPath, StringComparison.OrdinalIgnoreCase)) {
            isSpecialFolder = true;
            _specialFolder  = specialFolder;
            break;
        }
    }

    return isSpecialFolder;
}

If handling strings from dubious sources (the user :-) ), there are three caveats to keep in mind:

• Path.Combine vs. Path.Join, since they handle absolute paths (or paths that look like absolute paths) differently.
• Path.GetFullPath, which takes a string an produces the full and normalized version of it.
• GetFolderPath can return an empty string, which generates a System.ArgumentException: 'The path is empty. (Parameter 'path')' when used for creating a DirectoryInfo.

I like to keep this logic outside the method, but I am not sure if the OrdinalIgnoreCase or any other normalization is still necessary. I guess not.

P.S.: I think in modern lingo the method should be called TrySpecialFolder or something :-)

Astatine