public string StripNonAscii(string input)
{
string retval = string.Empty;
foreach (char c in input)
{
if (c >= 0x30 && c <= 0x39) retval += c;
else if (c >= 0x41 && c <= 0x5A) retval += c;
else if (c >= 0x61 && c <= 0x7A) retval += c;
}
return retval;
}