How do I convert an array of bytes to string with Delphi?

user_10466684 0
Viewed 1150

I am developing a project with Delphi and I want to convert the byte array to string type. How can I do?

Example C# codes:

private void ListenerOnDataTransmit(DataTransmitEventArgs e)
{
    transmittedMsg = BitConverter.ToString(e.TransmittedBytes, 0, e.TransmittedBytes.Length);
    try { Invoke(new EventHandler(UpdateTransmittedMessagesListView)); }
    catch { }
}
delphi-7 delphi
2 Answers

The BitConverter.ToString() method "Converts the numeric value of each element of a specified array of bytes to its equivalent hexadecimal string representation." You can do the same thing manually in Delphi 7 by using the SysUtils.IntToHex() function in a loop, eg:

uses
  ..., SysUtils;

var
  bytes: array of byte;
  s: string;
  i: Integer;
begin
  bytes := ...;
  s := '';
  if bytes <> nil then
  begin
    s := IntToHex(bytes[0], 2);
    for i := 1 to High(bytes) do
      s := s + '-' + IntToHex(bytes[i], 2);
  end;
end;
user_658630

I suspect you want a function that takes an array of bytes (or a raw pointer to bytes) and returns a string containing the data in hexadecimal form.

I always use the following routine of mine to do this:

function BytesToString(ABuf: PByte; ALen: Cardinal): string; overload;
const
  HexDigits: array[0..$F] of Char = '0123456789ABCDEF';
var
   i: Integer;
begin
   if ALen = 0 then
   begin
     Result := '';
     Exit;
   end;
   SetLength(Result, 3 * ALen - 1);
   Result[1] := HexDigits[ABuf^ shr 4];
   Result[2] := HexDigits[ABuf^ and $0F];
   for i := 1 to ALen - 1 do
   begin
     Inc(ABuf);
     Result[3*i + 0] := ' ';
     Result[3*i + 1] := HexDigits[ABuf^ shr 4];
     Result[3*i + 2] := HexDigits[ABuf^ and $0F];
   end;
end;

type
  TByteArray = array of Byte;

function BytesToString(ABytes: TByteArray): string; overload;
begin
  Result := BytesToString(PByte(ABytes), Length(ABytes));
end;

The first overload takes a raw pointer and a length, while the second overload takes a dynamic array of bytes.

This is a very fast implementation, since I do not use string concatenation (which requires constant heap reallocations).

The above code was written specifically for the old Delphi 7 compiler and RTL. A modern version would look more like this:

function BytesToString(ABuf: PByte; ALen: Cardinal): string; overload;
const
  HexDigits: array[0..$F] of Char = '0123456789ABCDEF';
var
   i: Integer;
begin
   if ALen = 0 then
    Exit('');
   SetLength(Result, 3 * ALen - 1);
   Result[1] := HexDigits[ABuf[0] shr 4];
   Result[2] := HexDigits[ABuf[0] and $0F];
   for i := 1 to ALen - 1 do
   begin
     Result[3*i + 0] := ' ';
     Result[3*i + 1] := HexDigits[ABuf[i] shr 4];
     Result[3*i + 2] := HexDigits[ABuf[i] and $0F];
   end;
end;

function BytesToString(ABytes: TArray<Byte>): string; overload;
begin
  Result := BytesToString(PByte(ABytes), Length(ABytes));
end;

The above code groups each byte using a space character. Of course, you might not want that, but doing it without grouping is a simpler task, so I'll leave that as an exercise.

user_2828480
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