HexStr to byte array

[danielw]

Sorry for my beginner question, but I want to get a byte array from an hex string.

String like

var
  s: String;
  ba: array[0..4] of Byte;
begin
  s:='05ff37ab';
  //Now i like to get ba calculated from s

[danielw]

ok but how will this help to parse the string into the byte array?

[User137]

You seem to have 4 hex values, so you only need to define 4 bytes like:

Code: [Select]

ba: array[0..3] of Byte;
From there http://delphi.about.com/od/mathematics/a/baseconvert.htm you can find:

Code: [Select]

function HexToInt(HexNum: string): LongInt;
begin
   Result:=StrToInt('$' + HexNum) ;
end;
Which you can convert to integer and somehow bit-slice bytes of it. Simpler would be to use Copy() function to slice the string instead into 4 pieces.

[Blaazen]

Try this (not tested):

Code: [Select]

uses ............., strutils;
....
var
  i, l: integer;
  str: String;
  ba: array [0..3] of Byte;
begin
  str:='05ff37ab';
  l:=length(str) div 2;
  for i:=0 to l-1 do
    ba[i]:=Hex2Dec(MidStr(str, i*2, 2));       

Of course, you can convert your string with Hex2Dec at once to LongWord.

[garlar27]

with the function "Hex2Dec" from "strutils" unit.

Look at this:
http://lazarus-ccr.sourceforge.net/docs/rtl/strutils/hex2dec.html

and here for the unit "strutils" :
http://lazarus-ccr.sourceforge.net/docs/rtl/strutils/index.html

and here for the RTL, FCL, and LCL:
http://lazarus-ccr.sourceforge.net/docs/rtl/
http://lazarus-ccr.sourceforge.net/docs/fcl/
http://lazarus-ccr.sourceforge.net/docs/lcl/

[danielw]

Thanks, it works.

But now I have the problem to do it the otherway round... I Have my Byte Array and try to convert it into a String (That is hex coded).

I found the function BinToHex, but it seams not to work with a array of byte or a byte only with PChar.

[Arbee]

How about:

Code: [Select]

type
THex = packed record
   case integer of
      0: (hexlong : longword);
      1: (hexbyte : packed array[0..3] of byte);
end;

var
str: string;
hexrec : THex;
   :    :
str := '05ff37ab';
hexrec.hexlong := Hex2Dec(str);   

if hexrec.hexbyte[0] = .........
Be aware that - at least on Windows - the sequence of bytes now is reversed hexbyte[0] contains the 'ab' and hexbyte[3] the '05';

The other way around if hexrec is filled with byte values .....

Code: [Select]

str := format('%.8x',[hexrec.hexlong]);


[User137]

Humm, i'll try

Code: [Select]

var str: String;
  ba: array [0..3] of Byte;
begin
  ...
  setlength(str,8);
  BinToHex(PChar(@ba), PChar(@str[1]), 4);

[Leledumbo]

absolute helps here:

Code: [Select]

type
  T4Byte = array [0 .. 3] of Byte;
var
  ba: T4Byte;
  shadow: LongWord absolute ba;
begin
  shadow := StrToInt('$' + YourHEXString);
  // ba now contains the bytes of YourHEXString, watch out with endianness
end;
For the other way around, just use HexStr on shadow.