I am testing some enhanced string related functions with which I am trying to use move as a way to copy strings around for faster, more efficient use without delving into pointers.

While testing a function for making a delimited string from a TStringList, I encountered a strange issue. The compiler referenced the bytes contained through the index when it was empty and when a string was added to it through move, index referenced the characters contained.

Here is a small downsized barebone code sample:-

unit UI;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Rtti, System.Classes,
  System.Variants, FMX.Types, FMX.Controls, FMX.Forms, FMX.Dialogs, FMX.Layouts,
  FMX.Memo;

type
  TForm1 = class(TForm)
    Results: TMemo;
    procedure FormCreate(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

function  StringListToDelimitedString
          ( const AStringList: TStringList; const ADelimiter: String ): String;
var
  Str           : String;
  Temp1         : NativeInt;
  Temp2         : NativeInt;
  DelimiterSize : Byte;

begin

  Result        := ' ';
  Temp1         := 0;
  DelimiterSize := Length ( ADelimiter ) * 2;

  for Str in AStringList do
    Temp1 := Temp1 + Length ( Str );

  SetLength ( Result, Temp1 );
  Temp1     := 1;

  for Str in AStringList do
  begin

    Temp2 := Length ( Str ) * 2;

    // Here Index references bytes in Result
    Move  ( Str [1],        Result [Temp1], Temp2 );

    // From here the index seems to address characters instead of bytes in Result
    Temp1 := Temp1 + Temp2;
    Move  ( ADelimiter [1], Result [Temp1], DelimiterSize );    
    Temp1 := Temp1 + DelimiterSize;

  end;

end;

procedure TForm1.FormCreate(Sender: TObject);
var
  StrList : TStringList;
  Str     : String;

begin

  // Test 1 : StringListToDelimitedString

  StrList := TStringList.Create;
  Str     := '';

  StrList.Add ( 'Hello1' );
  StrList.Add ( 'Hello2' );
  StrList.Add ( 'Hello3' );
  StrList.Add ( 'Hello4' );

  Str := StringListToDelimitedString ( StrList, ';' );
  Results.Lines.Add ( Str ); 
  StrList.Free;

end;

end.

Please devise a solution and if possible, some explanation. Alternatives are welcome too.