Detecting 'text' file type (ANSI vs UTF-8)

Question

I wrote an application (a psychological testing exam) in Delphi (7) which creates a standard text file - ie the file is of type ANSI.

Someone has ported the program

Answer 1

If the UTF file begins with the UTF-8 Byte-Order Mark (BOM), this is easy:

function UTF8FileBOM(const FileName: string): boolean;
var
  txt: file;
  bytes: array[0..2] of byte;
  amt: integer;
begin

  FileMode := fmOpenRead;
  AssignFile(txt, FileName);
  Reset(txt, 1);

  try
    BlockRead(txt, bytes, 3, amt);
    result := (amt=3) and (bytes[0] = $EF) and (bytes[1] = $BB) and (bytes[2] = $BF);
  finally    
    CloseFile(txt);
  end;

end;

Otherwise, it is much more difficult.