What is the best way to convert an array of bytes declared as TBytes to a RawByteString in Delphi 2009? This code actually works, maybe there is a faster way (without loop):
function Convert(Bytes: TBytes): RawByteString;
var
I: Integer;
begin
SetLength(Result, Length(Bytes));
for I := 0 to ABytes - 1 do
Result[I + 1] := AnsiChar(Bytes[I]);
end;
The best way is this:
function Convert(const Bytes: TBytes): RawByteString; inline;
begin
SetString(Result, PAnsiChar(pointer(Bytes)), length(Bytes));
end;
And don't forget to use const for Bytes parameters, for somewhat faster generated code.
The easiest way to convert bytes to a RawByteString is to use SetString().
Also, to avoid data loss if the RawByteString is ever assigned to other String types, you should assign a codepage to the RawByteString so that its character data gets converted correctly to the charset of the receiving String:
function Convert(const Bytes: TBytes): RawByteString;
begin
SetString(Result, PAnsiChar(PByte(Bytes))^, Length(Bytes));
SetCodePage(Result, ..., False);
end;
RawByteString is that it lacks codepage information in contrast to types like AnsiString or Utf8String.
Commented
Sep 12, 2019 at 7:41
RawByteString lacks a charset at compile time, but it inherits the runtime charset of whatever string is assigned to it. And a byte array has an implied charset to it, even if one is not carried in the byte payload itself. Like I said in my answer, RawByteString can be assigned to other string types, so it needs to carry a valid charset in its payload to facilitate proper assignments to avoid data loss
Commented
Sep 12, 2019 at 8:11
You could consider using move (untested)
function Convert(const Bytes: TBytes): RawByteString;
begin
SetLength(Result, Length(Bytes));
Move(Bytes[0], Result[1], Length(Bytes))
end;
And use "const" for the parameter so the array is not copied twice.
SetLength() will call ReallocMem to resize the existing RawByteString, so this version would perhaps unnecessary move() the previous data, without need, e.g. if you call this in a loop. SetString(Result,PAnsiChar(Bytes),length(Bytes) will be faster.
Commented
Jun 27, 2011 at 13:02
And remember to test:
IF Length(Bytes)>0 THEN MOVE.....
