Bit wise operations in C#

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Hi all,

It appears that the binary mucking I did earlier was right (but wrong) it but I
need to go over the binary number as bit field the below code is a rough lash up of how I want the 4 bit values from the Binary number

C#

char[] Input;

          for (int i = 0; i < 4; i++)
          {
              if (Input[i] > 'Z')
                  Input[i] -= 0x20;  // Convert lower case to upper case

              if ((Input[i] >= '0') && (Input[i] <= '9')) // First check to see if the number is 0 to 9
              {
                  Input[i] -= '0';  //If so, then subtract ascii ‘0’ from it

              }

              else if ((Input[i] >= 'A') && (Input[i] <= 'F'))// is this the hex codes A to F?
              {
                  Input[i] -= 0x37;  // Subtract 55 (0x37) so ascii A becomes 10
              }
             else
                  Input[i] = 0;  // Else invalid so substitute 0
          }

If you & with 0x08 and the result is not 0 then bit 3(4) is set

If you & with 0x04 and the result is not 0 then bit 2(3) is set

If you & with 0x02 and the result is not 0 then bit 1(2) is set

If you & with 0x01 and the result is not 0 then bit 0(1) is set

I want to do the old C route of doing it bit wise (a&&2) etc. Man I have to go home!

Glenn
(If the question peaks interest I will rephrase and make it cleaner tomorrow)

Umm it has, so rephrase time I have a character between 0 to 15 the code above (sort of) converted it to try to get 0 to 15 value out. I believe there should be a ConvertTo to do this but....
Glenn

Posted 14-Jan-13 7:35am

glennPattonWork3

Updated 14-Jan-13 22:36pm

v2

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Comments

Philippe Mori 14-Jan-13 19:00pm

Such low level manipulations generally does not make much sense in C#. You should use existing function to convert case or numbers or to check the category of a character (number, letter, space...)

4 solutions

Solution 2

On the off hand chance you are refering to checking bit flags you could do this in C#:

public enum BitFlag : byte
        {
            First=1,
            Second=2,
            Third=4,
            Fourth=8
        }

        public static string CheckFlag()
        {
            BitFlag bFlag = BitFlag.First | BitFlag.Third;
            StringBuilder result = new StringBuilder();

            if ((bFlag & BitFlag.First) == BitFlag.First)
                result.AppendLine("First");
            if ((bFlag & BitFlag.Second) == BitFlag.Second)
                result.AppendLine("Second");
            if ((bFlag & BitFlag.Third) == BitFlag.Third)
                result.AppendLine("Third");
            if ((bFlag & BitFlag.Fourth) == BitFlag.Fourth)
                result.AppendLine("Fourth");
            return result.ToString();
        }

Posted 14-Jan-13 8:05am

BC @ CV

Updated 15-Jan-13 3:41am

v3

Comments

Andreas Gieriet 14-Jan-13 20:06pm

Typo: it should be First = 1?
Cheers
Andi

BC @ CV 15-Jan-13 9:42am

Thanks, Correction made.

Solution 3

What you do is something like

C#

int i = int.TryParse(s, System.Globalization.NumberStyles.AllowHexSpecifier, null, out i)
      ? i
      : 0;

This has nothing to do with bit operators.
Andi

Posted 14-Jan-13 14:13pm

Andreas Gieriet

Solution 4

Hi.

I agree with Sergey Alexandrovich Kryukov about no bitwise operation can be found in your example.

However, you can rewrite your loop as:

C#

for (int i = 0; i < 4; i++)
{
    char ch = Input[i];
    ch = char.ToUpperInvariant(ch); // Convert any Lower case to Upper case
    int nValue = "0123456789ABCDEF".IndexOf(ch);
    if (nValue < 0) // -1 means not found: substitute with 0
        nValue = 0;
    Input[i] = nValue;
}

This applies to raw chars input like your example.

If instead you have a String as input, then you can use solution by Andreas Gieriet.

Regards,
Daniele.

Posted 14-Jan-13 21:32pm

Daniele Rota Nodari

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Sergey Alexandrovich Kryukov · Accepted Answer · 2013-01-14T07:57:00

In this code, there is nothing with resembles bit operations per se. Refer to the operator list:
http://msdn.microsoft.com/en-us/library/6a71f45d%28v=vs.110%29.aspx[^].

You will need binary shift '>>', '<<', binary AND, OR, XOR and NOT ('&', '|', '^', '~'). See also:
http://blog.typps.com/2007/10/bitwise-operators-in-c-or-xor-and-not.html[^].

—SA