Check whether a path is valid

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Directory.Exists?

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

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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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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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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);

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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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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;
}