string filter: detect non-ASCII signs

Question

I am creating an application which will send the input string to mobile device. Some devices have problems with encoding special characters so I would like to create a filte

Answer 1

Well you can do:

public static bool IsAllAscii(string text)
{
    return text.All(c => c >= ' ' && c <= '~');
}

I'm not sure you would really want to just remove the last character entered though - consider cutting and pasting a whole non-ascii string...