Check whether a path is valid

I am just wondering: I am looking for a way to validate if a given path is valid. (Note: I do not want to check if a file is existing! I only want to proof the validity of the path - So if a file could possibly exists at the location).

Problem is, I can't find anything in the .Net API. Due to the many formats and locations that Windows supports, I'd rather use something MS-native.

Since the function should be able to check against:

• Relative Paths (./)
• Absolute Paths (c:\tmp)
• UNC-Pathes (\some-pc\c$)
• NTFS-Limitations like the full path 1024 chars - If I am not mistaken exceeding the path will make a file inaccessible for many internal Windows f开发者_如何学JAVAunctions. Renaming it with Explorer still works
• Volume GUID Paths : "\?\Volume{GUID}\somefile.foo

Does anyone have a function like this?

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Try Uri.IsWellFormedUriString():

• The string is not correctly escaped.

    http://www.example.com/path???/file name
  

• The string is an absolute Uri that represents an implicit file Uri.

    c:\\directory\filename
  

• The string is an absolute URI that is missing a slash before the path.

    file://c:/directory/filename
  

• The string contains unescaped backslashes even if they are treated as forward slashes.

    http:\\host/path/file
  

• The string represents a hierarchical absolute Uri and does not contain "://".

    www.example.com/path/file
  

• The parser for the Uri.Scheme indicates that the original string was not well-formed.

    The example depends on the scheme of the URI.
  

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Or use the FileInfo as suggested in In C# check that filename is possibly valid (not that it exists).

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I haven't had any problems with the code below. (Relative paths must start with '/' or '\').

private bool IsValidPath(string path, bool allowRelativePaths = false)
{
    bool isValid = true;

    try
    {
        string fullPath = Path.GetFullPath(path);

        if (allowRelativePaths)
        {
            isValid = Path.IsPathRooted(path);
        }
        else
        {
            string root = Path.GetPathRoot(path);
            isValid = string.IsNullOrEmpty(root.Trim(new char[] { '\\', '/' })) == false;
        }
    }
    catch(Exception ex)
    {
        isValid = false;
    }

    return isValid;
}

For example these would return false:

IsValidPath("C:/abc*d");
IsValidPath("C:/abc?d");
IsValidPath("C:/abc\"d");
IsValidPath("C:/abc<d");
IsValidPath("C:/abc>d");
IsValidPath("C:/abc|d");
IsValidPath("C:/abc:d");
IsValidPath("");
IsValidPath("./abc");
IsValidPath("./abc", true);
IsValidPath("/abc");
IsValidPath("abc");
IsValidPath("abc", true);

And these would return true:

IsValidPath(@"C:\\abc");
IsValidPath(@"F:\FILES\");
IsValidPath(@"C:\\abc.docx\\defg.docx");
IsValidPath(@"C:/abc/defg");
IsValidPath(@"C:\\\//\/\\/\\\/abc/\/\/\/\///\\\//\defg");
IsValidPath(@"C:/abc/def~`!@#$%^&()_-+={[}];',.g");
IsValidPath(@"C:\\\\\abc////////defg");
IsValidPath(@"/abc", true);
IsValidPath(@"\abc", true);

---

private bool IsValidPath(string path)
{
    Regex driveCheck = new Regex(@"^[a-zA-Z]:\\$");
    if (!driveCheck.IsMatch(path.Substring(0, 3))) return false;
    string strTheseAreInvalidFileNameChars = new string(Path.GetInvalidPathChars());
    strTheseAreInvalidFileNameChars += @":/?*" + "\"";
    Regex containsABadCharacter = new Regex("[" + Regex.Escape(strTheseAreInvalidFileNameChars) + "]");
    if (containsABadCharacter.IsMatch(path.Substring(3, path.Length - 3)))
        return false;

    DirectoryInfo dir = new DirectoryInfo(Path.GetFullPath(path));
    if (!dir.Exists)
        dir.Create();
    return true;
}

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You can try this code:

try
{
  Path.GetDirectoryName(myPath);
}
catch
{
  // Path is not valid
}

I'm not sure it covers all the cases...

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There are plenty of good solutions in here, but as none of then check if the path is rooted in an existing drive here's another one:

private bool IsValidPath(string path)
{
    // Check if the path is rooted in a driver
    if (path.Length < 3) return false;
    Regex driveCheck = new Regex(@"^[a-zA-Z]:\\$");
    if (!driveCheck.IsMatch(path.Substring(0, 3))) return false;

    // Check if such driver exists
    IEnumerable<string> allMachineDrivers = DriveInfo.GetDrives().Select(drive => drive.Name);
    if (!allMachineDrivers.Contains(path.Substring(0, 3))) return false;

    // Check if the rest of the path is valid
    string InvalidFileNameChars = new string(Path.GetInvalidPathChars());
    InvalidFileNameChars += @":/?*" + "\"";
    Regex containsABadCharacter = new Regex("[" + Regex.Escape(InvalidFileNameChars) + "]");
    if (containsABadCharacter.IsMatch(path.Substring(3, path.Length - 3)))
        return false;
    if (path[path.Length - 1] == '.') return false;

    return true;
}

This solution does not take relative paths into account.

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The closest I have come is by trying to create it, and seeing if it succeeds.

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Get the invalid chars from System.IO.Path.GetInvalidPathChars(); and check if your string (Directory path) contains those or not.

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this accepts a path that could equate to a valid relative path too

string path = "yourPath";
bool pathIsValid = null;
try
{ 
    Path.GetFullPath(path);
    pathIsValid = true;
}
catch
{
    pathIsValid = false;
}

---

private bool IsValidPath(string path)
{
    Regex driveCheck = new Regex(@"^[a-zA-Z]:\\$");

    if (string.IsNullOrWhiteSpace(path) || path.Length < 3)
    {
        return false;
    }

    if (!driveCheck.IsMatch(path.Substring(0, 3)))
    {
        return false;
    }

    var x1 = (path.Substring(3, path.Length - 3));
    string strTheseAreInvalidFileNameChars = new string(Path.GetInvalidPathChars());
    strTheseAreInvalidFileNameChars += @":?*";
    Regex containsABadCharacter = new Regex("[" + Regex.Escape(strTheseAreInvalidFileNameChars) + "]");

    if (containsABadCharacter.IsMatch(path.Substring(3, path.Length - 3)))
    {
        return false;
    }

    var driveLetterWithColonAndSlash = Path.GetPathRoot(path);

    if (!DriveInfo.GetDrives().Any(x => x.Name == driveLetterWithColonAndSlash))
    {
        return false;
    }

    return true;
}

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Directory.Exists?

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You could try using Path.IsPathRooted() in combination with Path.GetInvalidFileNameChars() to make sure the path is half-way okay.