How to remove illegal characters from path and filenames?

Question

I need a robust and simple way to remove illegal path and file characters from a simple string. I\'ve used the below code but it doesn\'t seem to do anything, what am I miss

Answer 1

I created an extension method that combines several suggestions:

1. Holding illegal characters in a hash set
2. Filtering out characters below ascii 127. Since Path.GetInvalidFileNameChars does not include all invalid characters possible with ascii codes from 0 to 255. See here and MSDN
3. Possiblity to define the replacement character

Source:

public static class FileNameCorrector
{
    private static HashSet invalid = new HashSet(Path.GetInvalidFileNameChars());

    public static string ToValidFileName(this string name, char replacement = '\0')
    {
        var builder = new StringBuilder();
        foreach (var cur in name)
        {
            if (cur > 31 && cur < 128 && !invalid.Contains(cur))
            {
                builder.Append(cur);
            }
            else if (replacement != '\0')
            {
                builder.Append(replacement);
            }
        }

        return builder.ToString();
    }
}