How do I check for illegal characters in a path?

Question

Is there a way to check if a String meant for a path has invalid characters, in .Net? I know I could iterate over each character in Path.InvalidPathChars to see if my String contained one, but I'd prefer a simple, perhaps more formal, solution.

Is there one?

I've found I still get an exception if I only check against Get

Update:

I've found GetInvalidPathChars does not cover every invalid path character. GetInvalidFileNameChars has 5 more, including '?', which I've come across. I'm going to switch to that, and I'll report back if it, too, proves to be inadequate.

Update 2:

GetInvalidFileNameChars is definitely not what I want. It contains ':', which any absolute path is going to contain ("C:\whatever"). I think I'm just going to have to use GetInvalidPathChars after all, and add in '?' and any other characters that cause me problems as they come up. Better solutions welcome.

Answer 1

InvalidPathChars is deprecated. Use GetInvalidPathChars() instead:

    public static bool FilePathHasInvalidChars(string path)     {          return (!string.IsNullOrEmpty(path) && path.IndexOfAny(System.IO.Path.GetInvalidPathChars()) >= 0);     } 

Edit: Slightly longer, but handles path vs file invalid chars in one function:

    // WARNING: Not tested     public static bool FilePathHasInvalidChars(string path)     {         bool ret = false;         if(!string.IsNullOrEmpty(path))         {             try             {                 // Careful!                 //    Path.GetDirectoryName("C:\Directory\SubDirectory")                 //    returns "C:\Directory", which may not be what you want in                 //    this case. You may need to explicitly add a trailing \                 //    if path is a directory and not a file path. As written,                  //    this function just assumes path is a file path.                 string fileName = System.IO.Path.GetFileName(path);                 string fileDirectory = System.IO.Path.GetDirectoryName(path);                  // we don't need to do anything else,                                     // if we got here without throwing an                                      // exception, then the path does not                                     // contain invalid characters             }             catch (ArgumentException)             {                                     // Path functions will throw this                                      // if path contains invalid chars                 ret = true;             }         }         return ret;     } 

Answer 2

Be careful when relying on Path.GetInvalidFileNameChars, which may not be as reliable as you'd think. Notice the following remark in the MSDN documentation on Path.GetInvalidFileNameChars:

The array returned from this method is not guaranteed to contain the complete set of characters that are invalid in file and directory names. The full set of invalid characters can vary by file system. For example, on Windows-based desktop platforms, invalid path characters might include ASCII/Unicode characters 1 through 31, as well as quote ("), less than (<), greater than (>), pipe (|), backspace (\b), null (\0) and tab (\t).

It's not any better with Path.GetInvalidPathChars method. It contains the exact same remark.