Question : C# - Convert byte[] to bit mask

Experts,

I'm writing an web app which contains a large series of Checkboxes on a page. Once the user selects which options he/she wants I am creating a byte array like this:

//Just using 4 for simplicity:
byte[] options = new byte[4]
options[0] = Convert.ToByte(cbOption1.Checked);
options[1] = Convert.ToByte(cbOption2.Checked);
options[2] = Convert.ToByte(cbOption3.Checked);
options[3] = Convert.ToByte(cbOption4.Checked);

So saying that options 1 and 2 where checked I will end up with a byte[] array looking like this: 1100, which is expected. I want to convert this to an integer (i.e. a bitmask) which 1100 should equal 12.

So I googled "C# byte[] to int" and most everything comes up using the BitConverter class, but I'm getting some weird values.

One example shows the checking for LittleEndian processor architecture. So:

if(BitConverter.IsLittleEndian)
Array.Reverse(options);

int optionBitMask = BitConverter.ToInt32(options, 0);

And optionBitMask shows up as 16,842,752.

If I remove the reversing for LittleEndian and just use:

int optionBitMask = BitConverter.ToInt32(options, 0);

Then optionBitMask shows up as 257.

I'm not sure what I'm doing wrong. How do I get an int value of 12 from a byte[] containing 1100 ?

Answer : C# - Convert byte[] to bit mask

You're storing "bit" values in an entire byte for each position. You would need to treat each position as a bit rather than a byte. You can do so by working with the value of each byte and using a combination of shift and bitwise-or operations:

                       
             byte[] data = new byte[] { 1, 1, 0, 0 };
int result = 0;

for (int i = data.Length - 1; i >= 0; i--)
{
    result |= (data[i] << (data.Length - (i + 1)));
}

Console.WriteLine(result);