Project Structure

• Dates1.dpr
• Dates1Form.pas
• Dates1Form.dfm

program Dates1;

uses
  Forms,
  Dates1Form in 'Dates1Form.pas' {Form1};

{$R *.RES}

begin
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

unit Dates1Form;

interface

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

type
  TDate = class
    Month, Day, Year: Integer;
    procedure SetValue (m, d, y: Integer);
    function LeapYear: Boolean;
  end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    EditYear: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TDate.SetValue (m, d, y: Integer);
begin
  Month := m;
  Day := d;
  Year := y;
end;

function TDate.LeapYear: Boolean;
begin
  // call IsLeapYear in SysUtils.pas
  Result := IsLeapYear (Year);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  ADay: TDate;
begin
  // create an object
  ADay := TDate.Create;
  // use the object
  ADay.SetValue (1, 1, StrToInt (EditYear.Text));
  if ADay.LeapYear then
    ShowMessage ('Leap year: ' + IntToStr (ADay.Year));
  // destroy the object
  ADay.Free;
end;

end.

object Form1: TForm1
  Left = 192
  Top = 107
  Width = 291
  Height = 186
  Caption = 'Dates1'
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
  object Label1: TLabel
    Left = 72
    Top = 88
    Width = 25
    Height = 13
    Caption = 'Year:'
  end
  object Button1: TButton
    Left = 72
    Top = 48
    Width = 130
    Height = 25
    Caption = 'Leap Year?'
    TabOrder = 0
    OnClick = Button1Click
  end
  object EditYear: TEdit
    Left = 104
    Top = 84
    Width = 98
    Height = 21
    Color = clWindow
    TabOrder = 1
    Text = '2000'
  end
end