private string AppendChecksum(string data)
{
// append the checksum if necessary
if (useChecksum)
{
if (Checksum == null)
{
Checksum = new Modulo10Checksum();
}
data += Checksum.Calculate(data);
}
return(data);
}
protected string Validate(string data, int fullLength)
{
// check for non digits
if (!new Regex(@"^\d+$").IsMatch(data))
{
throw new BarCodeFormatException("The barcode has non-numeric data.");
}
// check the length, it can be full or missing the check digit
if (data.Length < fullLength - 1 || data.Length > fullLength)
{
throw new BarCodeFormatException("Invalid length for barcode.");
}
// check or calculate and append the check digit
if (Checksum == null)
{
Checksum = new Modulo10Checksum();
}
if (data.Length == fullLength)
{
// check if the check digit in the string is right
string checksum = Checksum.Calculate(data.Substring(0, fullLength - 1));
if (data[fullLength - 1].ToString() != checksum)
{
throw new BarCodeFormatException("Invalid check digit.");
}
}
else
{
// append the check digit
data += Checksum.Calculate(data);
}
return(data);
}
