function StrReplace(Strng, Old, New: string; Anzahl: Word; 
  IgnoreCase: boolean): string; 
var hlp, such: string; 
  p, lg, x: integer; 
begin 
  result := strng; 
  lg := length(old); 
  if Ignorecase then begin 
    hlp := ansilowercase(strng); 
    such := ansilowercase(old); 
  end else begin 
    hlp := strng; 
    such := old; 
  end; 
  for x := 0 to anzahl - 1 do begin 
    p := pos(such, hlp); 
    if p = 0 then break 
    else begin 
      delete(hlp, p, lg); 
      delete(result, p, lg); 
      insert(new, hlp, p); 
      insert(new, result, p); 
    end; 
  end; 
end; 
 
function StringReplaceBack(s, such, ersatz: string; Anzahl: Word; 
  IgnoreCase: boolean): string; 
var 
  lg, x: integer; 
  newstr, posstr: string; 
begin 
  if anzahl > 0 then begin 
    if IgnoreCase then begin 
      newstr := AnsiLowerCase(s); 
      such := AnsiLowerCase(such); 
    end else newstr := s; 
    lg := length(such); 
    posstr := ''; 
    for x := length(s) downto 1 do begin 
      posstr := newstr[x] + posstr; 
      if ansipos(such, posstr) > 0 then begin 
        delete(s, x, lg); 
        delete(posstr, 1, lg); 
        insert(ersatz, s, x); 
        dec(anzahl); 
        if anzahl = 0 then break; 
      end; 
    end; 
  end; 
  result := s; 
end; 
 
// Beispielaufrufe 
 
procedure TForm1.Button5Click(Sender: TObject); 
begin 
  showmessage(stringreplaceback('Es geht um den Penemekenel', 'E', 'a', 5, 
    true)); 
end; 
procedure TForm1.Button6Click(Sender: TObject); 
begin 
  showmessage(StrReplace('Panamakanal', 'a', 'ie', 3, false)); 
end;