Logical AND problem ?

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Hi All,

Bit of Bizzar question but I have some data that I have to logical '&' with a mask
to allow the data to be read off correctly. The issue is in the below code

C#

//Status (bit 4 Status) – if bit 4 = 0 then ‘False’ else ‘True’
            if ((Hexvalue2 & 0x0008) == 0)
            {
                MessageBox.Show("hello bit 4 not set");
                //checkBox4.Checked = false;
                label10.Text = " Status-";
               label9.Text += "False";
            }
            else
            {
                MessageBox.Show("bit 4 set");
                //checkBox4.Checked = true;
                label10.Text = "Status-";
                label9.Text += "True"; 
            }

I am pretty sure this is correct as I am doing it right as I have done similar elsewhere with success which means the bit is set in the byte I am reading in. I now have a giant question mark over my head, I am testing properly am I not?

Glenn

Posted 16-Jan-13 5:27am

glennPattonWork3

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2 solutions

Solution 2

Hi, it's quite hard to know what is going on here.
Could it be possible that your bit 4 is in fact the fifth (if you start counting at 0) ; in this case, bit 4 mask would be 0x0010 and not 0x0008.
But it's just a guess. Anyway, nothing seems wrong to me in your testing method.

Posted 16-Jan-13 5:44am

phil.o

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OriginalGriff · Accepted Answer · 2013-01-16T05:42:00

Solution 1

Not quite.
First off, "&" is a binary AND not a logical AND - the latter is "&&".
Secondly, 0x0008 does not have bit 4 set - it has bit 3 set:

Bit No  Hex   Decimal
 0       01       1
 1       02       2
 2       04       4
 3       08       8
 4       10      16
 5       20      32
 6       40      64
 7       80     128

Posted 16-Jan-13 5:42am

OriginalGriff

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phil.o 16-Jan-13 11:46am

You expressed that better than me. My 5.