Save Hex value or UTF-16 [LE] inside a file in Delphi 7 [Error in using these codes]

Question

Continuing from my previous question: How to save UTF-16 (Little Endian) and String value inside a file in Delphi 7?

When I use the following code from this answer:

uses
  Classes;
    
const
  BOM: WideChar = $FEFF;
var
  W: WideString;
  FS: TFileStream;
begin
  W := 'ᗿABC';
  FS := TFileStream.Create('text.txt', fmCreate);
  try
    FS.WriteBuffer(BOM, Sizeof(BOM));
    FS.WriteBuffer(PWideChar(W)^, Length(W) * Sizeof(WideChar));
  finally
    FS.Free;
  end;
end;

I have these problems:

1. when I used this: W := 'ᗿABC'; my IDE showed W := '?ABC'; Can I fix this problem? Because [?] is not my goal

2. When running the code, I get the error in the image:

Answer 1

1. The code editor in Delphi 7 does not support Unicode characters very well, if at all. You really should stop using a 25-year-old compiler and upgrade.

   In any case, try this instead:

   W := #$15FF'ABC';
   

   Or, you may have to resort to something more like this:

   W := WideChar($15FF) + WideString('ABC');
   

2. Try type-casting the integer value to WideChar:

   const
     BOM: WideChar = WideChar($FEFF);
   

   Otherwise, use Word instead of WideChar:

   const
     BOM: Word = $FEFF;