Delphi convert hex to PByteArray and back - delphi-10.3-rio

Question

How would I go about converting my hex string into pByteArray and back? using BinToHex and HexToBin RTL Functions.
My attempt is as followed.
function BuffertoHex(ABuf: pByte; ALen: Cardinal): string; overload;
begin
SetLength(Result, 3 * ALen - 1);
BintoHex(#ABuf, pchar(Result), sizeof(ABuf));
end;
function BuffertoHex(ABytes: TArray<byte>): string; overload;
begin
Result := BuffertoHex(pByte(ABytes), Length(ABytes));
end;
function HexToBuffer(LText: String): pByteArray; overload;
var
ABytes: TArray<byte>;
begin
FillChar(ABytes, sizeof(ABytes), #0);
HexToBin(pchar(LText), #ABytes, Length(ABytes));
Result := pByteArray(ABytes);
end;
My function BuffertoHex outputs odd hex values at the beginning. Example:
808725DBF40100001 00 00 00 00 00 00 0D 66 6F 6F 74 70 72 69 6E 74 ....
Yet How do I convert an array of bytes to string with Delphi? approach works just fine. Example:
9D D0 01 00 00 01 00 00 00 00 00 00 0D 66 6F 6F 74 ....

Answer 1

You got a few mistakes in your sources:
SizeOf is a function that return size of variable, not size of data;
You do not get any memory of your result variable, so the memory manager will think that memory of ABytes variable is not used when you leave the function and can use it for another purpose.
Here is simplified workable source of your function:
function HexToBuffer(const LText: String; out ALength : cardinal): pByteArray;
begin
ALength := length(LText) div 2; //calculate length of result (div 2 coz string 'FF' is 1 byte with value 255)
GetMem(Result, ALength); //get memory for result variable
HexToBin(PChar(LText), Result^, ALength); //do converting
end;
Using:
procedure TForm2.Button1Click(Sender: TObject);
var
xBytes: pByteArray;
l : cardinal;
i: Integer;
begin
xBytes := HexToBuffer('FF8000', l);
try
for i := 0 to l - 1 do
xBytes[i].ToString; //do your staff
finally
FreeMem(xBytes);
end;
end;