“Simple Calculator” dengan Delphi 2010

Setelah sebelumnya saya adaptasikan dengan Visual Baic 6.0 dan Visual Basic.NET 2010 sekarang saya terapkan dengan Delphi 2010. Baik logika program dan tampilan form tidak ada yang dirubah. Jadi bila teman-teman dapat membedakan secara langsung dimana letak perbedaan diantara ketiga bahasa pemrograman. Mana yang menurut teman-teman lebih mudah di pergunakan? silahkan teman-teman tentukan sendiri.

1. Jalankan terlebih dahulu aplikasi Delphi 2010

2. Pada jendela “Welcome Page” pilih  “New Project…”

3. Pada jendela “New Items” pilih “Delphi projects” lalu pilih “VCL Forms Application” kemudian pilih “OK”

4. Berikut seting kontrol properti yang terdapat pada aplikasi ini:

Object	Name	Properties	Setting
TForm1	Form1	Border Style Caption Position	bsSingle Simple Calculator poScreenCenter
TLabel	Label1	Caption	First Number:
TEdit	edtFirst	Alignment Text	taRightJustify (Empty)
TLabel	Label2	Caption	Second Number:
TEdit	edtSecond	Alignment Text	taRightJustify (Empty)
TButton	btnAdd	Caption	Add
TButton	btnSubtract	Caption	Subtract
TButton	btnMultiple	Caption	Multiple
TButton	btnDivide	Caption	Divide
TLabel	Label3	Caption	Result:
TEdit	edtResult	Alignment Text	taRightJustify (Empty)
TButton	btnClear	Caption	Clear
TButton	btnExit	Caption	E&xit

5. Berikut event program aplikasi ini:

unit untSimpleCalculator;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    edtFirst: TEdit;
    Label2: TLabel;
    edtSecond: TEdit;
    btnAdd: TButton;
    btnSubtract: TButton;
    btnMultiple: TButton;
    btnDivide: TButton;
    Label3: TLabel;
    edtResult: TEdit;
    btnClear: TButton;
    btnExit: TButton;
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure btnExitClick(Sender: TObject);
    procedure edtFirstKeyPress(Sender: TObject; var Key: Char);
    procedure edtSecondKeyPress(Sender: TObject; var Key: Char);
    procedure edtSecondChange(Sender: TObject);
    procedure DisableButton;
    procedure EnableButton;
    procedure btnClearClick(Sender: TObject);
    procedure btnAddClick(Sender: TObject);
    procedure btnSubtractClick(Sender: TObject);
    procedure btnMultipleClick(Sender: TObject);
    procedure btnDivideClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnAddClick(Sender: TObject);
begin
  edtResult.Text:=FloatToStr(StrToFloat(edtFirst.Text) + StrToFloat(edtSecond.Text));
end;

procedure TForm1.btnClearClick(Sender: TObject);
begin
  edtFirst.Clear;
  edtSecond.Clear;
  edtResult.Clear;
  DisableButton;
  edtFirst.SetFocus;
end;

procedure TForm1.btnDivideClick(Sender: TObject);
begin
  edtResult.Text:=FloatToStr(StrToFloat(edtFirst.Text) / StrToFloat(edtSecond.Text));
end;

procedure TForm1.btnExitClick(Sender: TObject);
begin
  Close;
end;

procedure TForm1.btnMultipleClick(Sender: TObject);
begin
  edtResult.Text:=FloatToStr(StrToFloat(edtFirst.Text) * StrToFloat(edtSecond.Text));
end;

procedure TForm1.btnSubtractClick(Sender: TObject);
begin
  edtResult.Text:=FloatToStr(StrToFloat(edtFirst.Text) - StrToFloat(edtSecond.Text));
end;

procedure TForm1.edtFirstKeyPress(Sender: TObject; var Key: Char);
begin
  if (key in ['0'..'9',#8,#13,'-','.']) then inherited
  else key:=#0;

  if key=chr(13) then Perform(WM_NEXTDLGCTL, 0, 0);
end;

procedure TForm1.edtSecondChange(Sender: TObject);
begin
  if (edtSecond.Text<>'') then EnableButton
  else DisableButton;
end;

procedure TForm1.edtSecondKeyPress(Sender: TObject; var Key: Char);
begin
  if (key in ['0'..'9',#8,#13,'-','.']) then inherited
  else key:=#0;

  if key=chr(13) then Perform(WM_NEXTDLGCTL, 0, 0);
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  case MessageDlg('Exit program',mtConfirmation,[mbYes, mbNo],0) of
    mrOk: Close;
    mrNo: Action:=caNone;
  end;
end;

procedure TForm1.DisableButton;
begin
  btnAdd.Enabled:=False;
  btnSubtract.Enabled:=False;
  btnMultiple.Enabled:=False;
  btnDivide.Enabled:=False;
  edtResult.Enabled:=False;
  btnClear.Enabled:=False;
end;

procedure TForm1.EnableButton;
begin
  btnAdd.Enabled:=True;
  btnSubtract.Enabled:=True;
  btnMultiple.Enabled:=True;
  btnDivide.Enabled:=True;
  edtResult.Enabled:=True;
  btnClear.Enabled:=True;
end;

end.

6. Pilih tombol “Run” atau teman-teman bisa langsung menekan tombol “F9” pada keyboard