Hi, In net 8. string DriectoryName = "\V530-DANIS"; \V530-DANIS => is not unc but new Uri(DirectoryName).IsUnc => return true and also Uri.TryCreate(DirectoryName, UriKind.Absolute, out Uri uri) && uri != null && uri.IsUnc => return true How I can check it return false ? Thanks, Thanks,

I don't see that behavior. A URL uses / , not \ for pathing. Passing the value you gave to a Uri results in an exception because it cannot figure out what type of URI you're dealing with here. var items = new [] { "https://tempuri.org", "//server/share", "//server", "/server", @"\V530-DANIS" }; foreach (var item in items) { try { var isUnc = new Uri(item, UriKind.Absolute).IsUnc; Console.WriteLine($"{item} = {isUnc}"); } catch (Exception e) { Console.WriteLine($"{item} = ERROR: {e.Message}"); } };

How to test is path is unc

Accepted answer

Michael Taylor 51,346 Reputation points

2024-02-12T15:41:52.72+00:00
I don't see that behavior. A URL uses /, not \ for pathing. Passing the value you gave to a Uri results in an exception because it cannot figure out what type of URI you're dealing with here.

var items = new [] { "https://tempuri.org", "//server/share", "//server", "/server", @"\V530-DANIS" }; foreach (var item in items) { try { var isUnc = new Uri(item, UriKind.Absolute).IsUnc; Console.WriteLine($"{item} = {isUnc}"); } catch (Exception e) { Console.WriteLine($"{item} = ERROR: {e.Message}"); } };
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Dani_S 3,336 Reputation points

2024-02-12T16:26:57.2666667+00:00

How to test unc as valid path ? What it return when you have only server name without share?

Michael Taylor 51,346 Reputation points

2024-02-12T16:52:38.3166667+00:00

A path that is only a server name is a valid UNC path. //server/share is a share on a file server whereas //server is just the server.

If you want to find paths that follow the form //<server>/<share> then you can build your own function to do it. Regular expressions could be used or you could just keep it simple. Perhaps something as simple as this.

public static bool IsUncPath ( string value ) { if (!(value ?? "").StartsWith("//")) return false; //TODO: Add additional checks that you think are important such as: // - Look for at least 1 path separate to confirm the share is listed // - Check for invalid characters based upon Path.GetInvalidPathChars //...or just let other calls fail if the path isn't actually valid return true; }

Note that this just validates the string is probably a UNC path. It says nothing about whether it is actually valid or not. The only way to do that is to actually check for existence but note that permissions can return false positives.

Dani_S 3,336 Reputation points

2024-02-12T17:20:49+00:00

Hi, Please see picture:

Does this code check if unc path valid or not for every input? Uri uncUri = new Uri(DirectoryName); if (!Directory.Exists(uncUri.LocalPath)) { // errror message } continue process

Michael Taylor 51,346 Reputation points

2024-02-12T17:34:53.1266667+00:00

That is a valid UNC and Uri.IsUnc should return true. It meets the criteria of starting with double slashes and has the share name.

Dani_S 3,336 Reputation points

2024-02-12T17:46:26.21+00:00

But uri.isUnc return true if has only server name. And my code check if the path-directory exist. In case of only server name it will return false. Is it?

Dani_S 3,336 Reputation points

2024-02-12T17:57:47.6466667+00:00

My aim to check if user enter valid unc path -server + share n ame if not give error message.

Michael Taylor 51,346 Reputation points

2024-02-12T17:58:32.2233333+00:00

A server name only is a valid UNC. If you check for the path to exist then a single server name should return false. If that is your criteria then it would fail for just the server name. However it would also fail if you gave it a valid UNC path that doesn't exist or that you don't have access to.

You, as the user of your code, have to decide what it means to be "a valid UNC path". A valid UNC path is any string that meets the criteria for the UNC format. If you also need it to exist then you need to check for the path to exist as well. In that case a valid UNC, that doesn't exist or you don't have access to, is not valid.

Dani_S 3,336 Reputation points

2024-02-12T18:06:13.83+00:00

I.e for unc that define in other computer my code is not good?

Michael Taylor 51,346 Reputation points

2024-02-12T18:10:16.4+00:00

If your aim is to check for a valid UNC path then use Path.Exists to see if the path exists and you have access to it.

public static bool IsUncPath ( string value ) { if (!(value ?? "").StartsWith("//")) return false; //And path must exist return Path.Exists(value); }

Dani_S 3,336 Reputation points

2024-02-12T18:15:25.9933333+00:00

Path cover also remote unc that define on my computer.while directory exist not.is it?

Michael Taylor 51,346 Reputation points

2024-02-12T19:14:12.97+00:00

That code should work whether it is remote or not. Assuming the caller has permissions to the share then it should report that it exists.

Dani_S 3,336 Reputation points

2024-02-13T07:47:15.73+00:00

Hi, I testes you code it work with this code: \\ public`` ``static`` ``bool`` ``IsUncPath`` (`` string value ``) { if (!(value ?? "").StartsWith("\\\\")) return false; //And path must exist return Path.Exists(value); }

Michael Taylor 51,346 Reputation points

2024-02-13T15:32:37.4166667+00:00

So is your problem solved now or are you still having issues? If you are having issues then please provide sample input(s) that are causing issues and what you expect the results to be.

Dani_S 3,336 Reputation points

2024-02-13T16:15:40.7266667+00:00

Thank you very for your help. My last code works well.

Dani_S 3,336 Reputation points

2024-02-15T12:08:40.3633333+00:00

//And path must exist return Path.Exists(value); not working for remote UNC!!

Dani_S 3,336 Reputation points

2024-02-15T12:09:00.5366667+00:00

Any solution ?

Michael Taylor 51,346 Reputation points

2024-02-15T14:59:12.9433333+00:00

Path.Exists works for UNC paths. The caveat applies (as with all UNC stuff) that the user running the code must have access to the UNC. If it triggers a login prompt when you try to map the drive in Explorer then it probably is going to fail on Path.Exists as well.

You could also try DirectoryInfo.Exists. It will likely behave the same way.

var exists = new DirectoryInfo(path).Exists;

Again, this assumes you have access to the path as the current user without a login prompt.
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How to test is path is unc

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