C# help padding Byte with zeros

[Maja Gajic]

Hello I am quiet new at C# programming so would appreciate any help. I am writing a program to communicate via RS232 with a machine and need to send it a packet in the form:

{ <DLE> , <STX> , "G" , <DLE> , <ETX> , <CRC> , <CRC> }

byte[] byteToSend = new byte[] { 0x10, 0x02, 0x47, 0x10, 0x03, CRC , CRC };

My two byte CRC is 0x421F and I need to split it into two bytes to fit the format above.
When I convert to binary I get < 01000010 | 00011111 >
Obviously the left zero padding on the MSB doesn't matter but the padding on the LSB is important and I think converting it into < 0x42 | 0x1F > is not correct as it loses the zero padding on the LSB.

Thanks for any help
Maja :)

[GaryTexmo]

It shouldn't matter, it's still a byte. I assume you're printing out the value with Convert.ToStrin g(0x1F, 2)? If so, that's the correct output it's just not padded with zeros. Have a look at the following...

I take the full value, split it into high and low bytes, then rebuild it to get the same value I started with. The information should be preserved :)

static void Main(string[] args)
{
    short CRC_raw = 0x421F;
    byte CRC_high;
    byte CRC_low;
    short CRC_rebuilt;

    Console.WriteLine("    Raw: " + ToHex(CRC_raw) + " -- " + ToBinary(CRC_raw));

    CRC_low = (byte)(CRC_raw & (short)0x00FF);
    CRC_high = (byte)(CRC_raw >> 8);

    Console.WriteLine("    Low: " + ToHex(CRC_low) + " -- " + ToBinary(CRC_low));
    Console.WriteLine("   High: " + ToHex(CRC_high) + " -- " + ToBinary(CRC_high));

    CRC_rebuilt = (short)(((0x0000 | CRC_high) << 8) | CRC_low);

    Console.WriteLine("Rebuilt: " + ToHex(CRC_rebuilt) + " -- " + ToBinary(CRC_rebuilt));
}

static string ToHex(int val)
{
    return "0x" + val.ToString("X");
}

static string ToBinary(int val)
{
    return Convert.ToString(val, 2);
}

Output:

Raw: 0x421F -- 100001000011111
Low: 0x1F -- 11111
High: 0x42 -- 1000010
Rebuilt: 0x421F -- 100001000011111

[Maja Gajic]

Great that makes more sense now, Thanks for the clever code!