TByteRec Conversion

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June 26th, 2012, 07:58 PM

EddiRae

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TByteRec Conversion

Hello again,
I came across the code below and I am trying to convert to VB.Net. I have never seen the ".na", ".nd", or the ".nv"

Can someone tell me what this code is doing and how to convert it to VB.Net?

Code:

type
  TByteRec = record
  acc, nd, nv, na: Byte;
end;

var
  Buf: String;
  i, iacc, k, n: Integer;

iacc := qPFTREP_CODE.AsInteger;
i := TByteRec(iacc).na;              // n acceptable
Buf := Buf + IntToStr(i) + ',';
i := TByteRec(iacc).nd;              // n deleted
Buf := Buf + IntToStr(i) + ',';
k := TByteRec(iacc).nv;           // compute nvext

Thanks for your help in advance!!
Eddi Rae

June 26th, 2012, 08:50 PM

clivew

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TByteRec is declared as a record containing four individual bytes.
In this code it gives you a convenient way to access the individual byes that comprise the integer iacc.

BTW: Buf needs to be initialized somewhere. Either to your starting value or to an empty string. Local variables are not magically initialized by the compiler the way object fields are initialized during creation. However, as you are converting away from Delphi this is probably irrelevant.

Clive

June 28th, 2012, 04:43 PM

EddiRae

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Thanks for the explanation.

Yes. Buf is being initialized. This is just the part of the code that I needed an explanation on.

Thanks again!!
Eddi Rae

July 1st, 2012, 10:40 AM

EddiRae

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Clive,
I was noticing that the .na, .nd and .nv are not defined.

Since I am converting to VB.Net, how would these correlate to the different sections on an integer.

I am needing to come up with the same values.

Thanks in advance
Eddi Rae

July 1st, 2012, 12:29 PM

clivew

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Quote:

I was noticing that the .na, .nd and .nv are not defined.

Take another look at the record definition.
Each one is defined as Byte.
Their names are simply field names assigned for the benefit of the programmer,
they have no significance to the compiler beyond identifying which Byte is being referenced.

They could just as easily have been named a,b,c,d (as I have done in my own code).
I have to assume that .na, .nd and .nv have some human meaning to the task at hand.

Hope this makes sense.

WARNING: When splitting an integer into its individual bytes you need to be aware of any big endian / little endian issues.

Clive

July 2nd, 2012, 06:33 PM

EddiRae

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type
TByteRec = record
acc, nd, nv, na: Byte;
end;

So in this instance, I am breaking the TByteRec into four bytes.
acc is first byte, nd is second byte, nv is third byte and na is fourth byte.

Is my understanding correct?

I found this link that explains the use of the TByteRec
http://docs.embarcadero.com/product...ssions_xml.html .

Let me know if I am on the right track.

Thanks!!

July 2nd, 2012, 07:04 PM

clivew

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Yes. You are on the right track.

Of course, the TByteRec you referenced in the URL is a two byte record suitable for handling a Word.
Your TByteRec is a four byte record capable of handling a 32-bit integer.

I'm sure you realized that.

TByteRec Conversion

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