Ich versuch &verfehle beim Programmieren eines Bruchrechners

[himitsu]

Delphi-Quellcode:

Unit Unit1;

Interface
  Uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls;

  Type TForm1 = Class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    e_z1: TEdit;
    e_n1: TEdit;
    e_z2: TEdit;
    e_n2: TEdit;
    e_ergz: TEdit;
    e_ergn: TEdit;
    b_plus1: TButton;
    b_minus: TButton;
    b_mal: TButton;
    b_div: TButton;
    Button5: TButton;
    Button6: TButton;
    Procedure Button1bis4Click(Sender: TObject);
    Procedure Button5Click(Sender: TObject);
    Procedure Button6Click(Sender: TObject);
  End;

  Var Form1: TForm1;

Implementation
  {$R *.dfm}

  Procedure TForm1.Button1bis4Click(Sender: TObject);
    Var az, an, bz, bn, ez, en: Integer;

    Begin
      az := StrToInt(e_z1.Text);
      an := StrToInt(e_n1.Text);
      bz := StrToInt(e_n2.Text);
      bn := StrToInt(e_z2.Text);

      If Sender = b_plus Then Begin
        az := az * bn;  {erweitern}
        bz := bz * an;
        an := an * bn:
        {bn := bn * an:}
        ez := az + bz;  {rechnen}
        en := an:
      End;
      If Sender = b_minus Then Begin
        az := az * bn;  {erweitern}
        bz := bz * an;
        an := an * bn:
        {bn := bn * an:}
        ez := az - bz;  {rechnen}
        en := an:
      End;
      If Sender = b_mal Then Begin
        ez := az * bz;  {rechnen}
        en := an * bn:
      End;
      If Sender = b_div Then Begin
        ez := az * bn;  {rechnen}
        en := an * bz:
      End;

      {kürzen}
      For I := Min(Abs(ez), Abs(en)) downto 2 do
        If (ez mod I2 = 0) and (en mod I2 = 0) Then Begin
          ez := ez div I2;
          en := en div I2;
          Break;
        End;

      e_ergz.Text := IntToStr(ez);
      e_ergn.Text := IntToStr(en);
    End;

  Procedure TForm1.Button5Click(Sender: TObject);
    Begin
      e_z1.Text := 0;
      e_n1.Text := 0;
      e_n2.Text := 0;
      e_z2.Text := 0;
      e_ergz.Text := 0;
      e_ergn.Text := 0;
    End;

  Procedure TForm1.Button6Click(Sender: TObject);
    Begin
      Application.ProcessMessages;
    End;

End.