This example uses the following code to display characters that are not allowed in file and path names.

string txt = "";
foreach (char ch in Path.GetInvalidFileNameChars())
{
    if (Char.IsWhiteSpace(ch) || Char.IsControl(ch))
    {
        txt += "<" + (int)ch + "> ";
    }
    else
    {
        txt += ch + " ";
    }
}
lblInvalidFileNameChars.Text = txt;

txt = "";
foreach (char ch in Path.GetInvalidPathChars())
{
    if (Char.IsWhiteSpace(ch) || Char.IsControl(ch))
    {
        txt += "<" + (int)ch + "> ";
    }
    else
    {
        txt += ch + " ";
    }
}
lblInvalidPathChars.Text = txt;

The code simply loops through the values returned by Path.GetInvalidFileNameChars and Path.GetInvalidPathChars. It displays the printable characters and shows the numeric values of the whitespace and control characters.

Download example