Byte formatting

Question

Hello I'am new to using bytes in C#.

Say if I want to compare bytes based on the forms 0xxxxxxx and 1xxxxxxx. How would I get that first value for my comparison and at the same time remove it from the front?

Any help will be greatly appreciated.

What do you mean by "remove it from the front"? The front of what? Please clarify your question. — Jon Skeet, Sep 06 '13 at 19:15
yeah that's the term i'm looking for. I want to compare bits. Sorry I'm completely new to using bytes and bits. — Emre801, Sep 06 '13 at 19:17
First hit on google: _comparing bits c#_ http://stackoverflow.com/questions/1929343/bitwise-and-on-32-bit-integer — Jeroen van Langen, Sep 06 '13 at 19:18

Jeppe Stig Nielsen · Accepted Answer · 2013-09-06T19:35:18.553

Not sure I understand, but in C#, to write the binaray number 1000'0000, you must use hex notation. So to check if the left-most (most significant) bits of two bytes match, you can do e.g.

byte a = ...;
byte b = ...;

if ((a & 0x80) == (b & 0x80))
{
  // match
}
else
{
  // opposite
}

This uses bit-wise AND. To clear the most significant bit, you may use:

byte aModified = (byte)(a & 0x7f);

or if you want to assign back to a again:

a &= 0x7f;

score 0 · Answer 2 · edited Sep 06 '13 at 19:29

0

You need to use binary operations like

a&10000
a<<1

edited Sep 06 '13 at 19:29

MarcinJuraszek

124,003
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answered Sep 06 '13 at 19:19

MichaelT

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score 0 · Answer 3 · answered Sep 06 '13 at 20:25

This will check two bytes and compare each bit. If the bit is the same, it will clear that bit.

     static void Main(string[] args)
    {
        byte byte1 = 255;
        byte byte2 = 255;

        for (var i = 0; i <= 7; i++)
        {
            if ((byte1 & (1 << i)) == (byte2 & (1 << i)))
            {
                // position i in byte1 is the same as position i in byte2

                // clear bit that is the same in both numbers
                ClearBit(ref byte1, i);
                ClearBit(ref byte2, i);
            }
            else
            {
                // if not the same.. do something here
            }

            Console.WriteLine(Convert.ToString(byte1, 2).PadLeft(8, '0'));
        }
        Console.ReadKey();
    }

    private static void ClearBit(ref byte value, int position)
    {
        value = (byte)(value & ~(1 << position));
    }
}

Byte formatting

3 Answers3