Question

I have a checksum that I need to add to a ruby string in hex. I have been unable to convert the checksum successfully. I am relatively new to ruby, so I’m not sure if I’m missing something. Here is what I am doing:

  def get_checksum message
    # get the checksum
    cnt = 0
    lrc = 0
    while (cnt < message.length - 1)
      lrc = lrc ^ message[cnt].to_i
      cnt += 1
    end

    # return as hex
    lrc.to_s.each_byte.map { |b| b.to_s(16) + " " }.join
  end

I have some c# reference code as well, but have never used C# being a long time mac C/C++/Obj-C coder. Here is the C# code I am trying to convert:

// calculate LRC
private string GetChecksum(string inputstring)
{
    int checksum = 0;
    foreach (char c in inputstring)
    {
        checksum ^= Convert.ToByte(c);
    }
    return checksum.ToString("X2");
}

Any help would be appreciated.

Answer 1

.to_i will return 0 when called on a character.

def get_checksum message
   # get the checksum
   lrc = 0
   message.each_byte do |b|
      lrc = lrc ^ b
   end
   # return as hex
   lrc.to_s(16)
end