Check whether a path is valid

Question

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

Answer 1

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.
  

Answer 2

Directory.Exists?

Answer 3

You can try this code:

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

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

Answer 4

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;
}

Answer 5

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

Answer 6

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.