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//in OnClick-Ereignis (Objektinspektor - Ereignisse - OnClick - Doppelklick)
    Edit1.Text:='';					

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TEdit(Sender).Text:='';					

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unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ComCtrls, Tabnotbk;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Button1: TButton;
    Button2: TButton;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    ScrollBar1: TScrollBar;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

var
  l,b,h,v,o:real;
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
l:=strtofloat(edit1.text);
b:=strtofloat(edit2.text);
h:=strtofloat(edit3.text);
v:=l*b*h;
label1.caption:=floattostr(v);
o:=2*l*b+2*b*h+2*h*l;
label2.caption:=floattostr(o);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
close;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin

end;

end.					

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Edit1.Text:='';					

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procedure TForm1.Edit1Click(Sender: TObject);
begin
    Edit1.Text:='';
end;