// 1. Groß- und Kleinschreibung tauschen 
 
function AnsiInvertCase(s: Ansistring): Ansistring; 
const 
  g32 = [65 .. 90, 192 .. 222]; 
  k32 = [97 .. 122, 224 .. 254]; 
  g16 = [138, 140, 142]; 
  k16 = [154, 156, 158]; 
var 
  pbs, pbr: PByte; 
begin 
  result := s; 
  pbs := @s[1]; 
  pbr := @result[1]; 
  while pbs^ > 0 do 
  begin 
    if (pbs^ in k32) then 
      pbr^ := pbs^ - 32 
    else if (pbs^ in g32) then 
      pbr^ := pbs^ + 32 
    else if (pbs^ in k16) then 
      pbr^ := pbs^ - 16 
    else if (pbs^ in g16) then 
      pbr^ := pbs^ + 16 
    else if (pbs^ = 159) then 
      pbr^ := 255 
    else if (pbs^ = 255) then 
      pbr^ := 159 
    else 
      pbr^ := pbs^; 
    inc(pbs); 
    inc(pbr); 
  end; 
end; 
 
procedure TForm2.Button1Click(Sender: TObject); 
var 
  s, v: String; 
begin 
  s := 'ABCD abcd ÄÖÜ äöü ÁÇËÎ áçëî ŠŒŽ šœž'; 
  v := String(AnsiInvertCase(Ansistring(s))); 
  showmessage(s + #13 + v); 
end; 

// --------------------------------------------------------- 
 
// 2. Strings umdrehen 
//    Wer die Unit "StrUtils" besitzt, kann "AnsiReverseString()"
//    nutzen. Ansonsten:
 
function FlipString(const s: string): string; 
var 
  lg: integer; 
  ps, pr: PChar; 
begin 
  lg := length(s); 
  setlength(result, lg); 
  ps := @s[1]; 
  pr := @result[1]; 
  inc(pr, pred(lg)); 
  while ps^ > #0 do begin 
    pr^ := ps^; 
    inc(ps); 
    dec(pr); 
  end; 
end; 
 
 
// Beispielaufruf 
 
procedure TForm1.Button3Click(Sender: TObject); 
begin 
  Label3.caption := 'TSET NIE TSI SAD'; 
  Label4.caption := FlipString(Label3.caption); 
end;