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Word to byte

Posted on 2006-11-09
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Last Modified: 2008-03-15
Hi,

How to convert Word into array of bytes?
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Question by:S_Warrior
8 Comments
 
LVL 17

Accepted Solution

by:
TheRealLoki earned 25 total points
ID: 17909234
just use Lo() and Hi()
eg.

  var
    w: word;
    i: integer;
    results: array[0..1] of byte;
  begin
    w := 12345;
    results[0] := lo(w);
    results[1] := hi(w);
    for i := Low(results) to high(results) do
      memo1.lines.add(inttostr(results[i]));
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LVL 26

Assisted Solution

by:Russell Libby
Russell Libby earned 25 total points
ID: 17911260

You can also move the data, or just perform a simple cast of the word data.

Russell

-----------

eg:

var  w:       word;
     i:       integer;
     results: Array[0..1] of byte;
begin

  w:=12345;

  // Split high and low bytes
  results[0] := lo(w);
  results[1] := hi(w);
  for i := Low(results) to high(results) do
     memo1.lines.add(inttostr(results[i]));

  // Move data
  Move(w, results, SizeOf(Word));
  for i := Low(results) to high(results) do
     memo1.lines.add(inttostr(results[i]));

  // Cast data
  for i:=0 to 1 do
     memo1.lines.add(IntToStr(PByteArray(@w)^[i]));

end;
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LVL 14

Expert Comment

by:Pierre Cornelius
ID: 17912088
Another option is this:

type

  TWordBytes = record
    byte1, byte2: byte;
  end;

...
var ba: TWordBytes;
    w: word;
begin
  w:= 1000;
  ba:= TWordBytes(w);
  ShowMessage(IntToStr(ba.byte1)+', '+IntToStr(ba.byte2));
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LVL 27

Expert Comment

by:kretzschmar
ID: 17912177
0
 
LVL 17

Expert Comment

by:Wim ten Brink
ID: 17912974
Or, the most interesting solution:

program Project3;
{$APPTYPE CONSOLE}
var
  W: Word;
  B: array[0..1] of byte absolute W;
begin
  W := $1234;
  WriteLn(B[0]);
  WriteLn(B[1]);
  ReadLn;
end.

Keep in mind that words are stored with the low-byte first. Thus B[0] is the low byte and B[1] is the high byte. The absolute directive just tells Delphi that B is located at exactly the same address as W. Thus, no need to assign one to another or do some typecasting...

The use of Lo() and Hi() -as suggested by others- does tend to be a bit more reliable though, since your Pascal code might one day be compiled for a processor that doesn't do Little-Ednian storage of data. (Intel uses Little-Endian, meaning that in memory, the low byte comes before the high byte.)
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LVL 28

Expert Comment

by:ciuly
ID: 21094900
note: sorry, but the points (5) were not enough to split between all 4 of you so I went with the first 2 solutions.
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LVL 1

Expert Comment

by:Computer101
ID: 21133170
Forced accept.

Computer101
EE Admin
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