Check if a disk is in the drive with Delphi

function DiskInDrive(Drive: Char): Boolean;

var

  ErrorMode: Word;

begin

  { make it upper case }

  if Drive in ['a'..'z'] then

    Dec(Drive, $20);

  { make sure it's a letter }

  if not (Drive in ['A'..'Z']) then

    raise EConvertError.Create('Not a valid drive ID');

  { turn off critical errors }

  ErrorMode := SetErrorMode(SEM_FAILCRITICALERRORS);

  try

    { drive 1 = a, 2 = b, 3 = c, etc. }

    if DiskSize(Ord(Drive) - $40) = -1 then

      Result := false

    else

      Result := true;

  finally

    { Restore old error mode }

    SetErrorMode(ErrorMode);

  end;

end;