using System;

using System.Text;

​

public class BlockCheckCharacterCalculator

{

    public static void Main()

    {

        string data = "GAB2111FFFFFFFFFFFF0000";

        char blockCheckCharacter = CalculateBlockCheckCharacter(data);

        Console.WriteLine("Block Check Character: "+blockCheckCharacter);

        Console.WriteLine("QR Code: "+data + blockCheckCharacter);

    }

​

    public static char CalculateBlockCheckCharacter(string data)

    {

        byte xorResult = 0x00;

        foreach (char c in data)

        {

            xorResult ^= Convert.ToByte(c);

        }

​

        return Convert.ToChar(xorResult);

    }

}