Inserting my own illegal characters into Path.GetInvalidFileNameChars() in C#

How can I extend the Path.GetInvalidFileNameChars to include my own set of characters that is illegal in my application?

string invalid = new string(Path.GetInvalidFil开发者_JAVA技巧eNameChars()) + new string(Path.GetInvalidPathChars());

If I wanted to add the '&' as an illegal character, could I do that?

typeof(Path).GetField("InvalidFileNameChars", BindingFlags.NonPublic | BindingFlags.Static).SetValue(null, new[] { 'o', 'v', 'e', 'r', '9', '0', '0', '0' });

Try this:

var invalid = Path.GetInvalidFileNameChars().Concat(new [] { '&' });

This will yeild an IEnumerable<char> with all invalid characters, including yours.

Here is a full example:

using System.IO;
using System.Linq;

class Program
{
    static void Main()
    {
        // This is the sequence of characters
        var invalid = Path.GetInvalidFileNameChars().Concat(new[] { '&' });
        // If you want them as an array you can do this
        var invalid2 = invalid.ToArray();
        // If you want them as a string you can do this
        var invalid3 = new string(invalid.ToArray());
    }
}

You can't modify an existing function, but you can write a wrapper function that returns Path.GetInvalidFileNameChars() and your illegal characters.

public static string GetInvalidFileNameChars() {
    return Path.GetInvalidFileNameChars().Concat(MY_INVALID_FILENAME_CHARS);
}

An extension method is your best bet here.

public static class Extensions
{
    public static char[] GetApplicationInvalidChars(this char[] input)
    {
        //Your list of invalid characters goes below.
        var invalidChars = new [] { '%', '#', 't' };
        return String.Concat(input, invalidChars).ToCharArray();
    }
}

Then use it as follows:

string invalid = Path.GetInvalidFileNameChars().GetApplicationInvalidChars();

It will concatenate your invalid characters to what's already in there.

First create a helper class "SanitizeFileName.cs"

public class SanitizeFileName
{
   public static string ReplaceInvalidFileNameChars(string fileName, char? replacement = null)
   {
      if (fileName != null && fileName.Length != 0)
      {
         var sb = new StringBuilder();
         var badChars = new[] { ',', ' ', '^', '°' };
         var inValidChars = Path.GetInvalidFileNameChars().Concat(badChars).ToList();

         foreach (var @char in fileName)
         {
            if (inValidChars.Contains(@char))
            {
               if (replacement.HasValue)
               {
                  sb.Append(replacement.Value);
               }
               continue;
            }
            sb.Append(@char);
         }
         return sb.ToString();
      }
      return null;
   }
}

Then, use it like this:

var validFileName = SanitizeFileName.ReplaceInvalidFileNameChars(filename, '_');

in my case, i had to clean up the "filename" on the "Content-Deposition" in Response Headers in a c# download method.

Response.AddHeader("Content-Disposition", "attachment;filename=" + validFileName);