子界类型的应用

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  edit1.Text := '';
  edit2.Text := '';
end;

procedure TForm1.Button2Click(Sender: TObject);
type                                              //子界类型定义和声明
  leap = 1950..2050;
var
  leapyear: leap;
  inyear,a,b,c: integer;
begin
  inyear := strtoint(edit1.Text);
  leapyear := inyear;                             //子界类型赋值
  a := leapyear mod 4;                            //子界类型运算
  b := leapyear mod 100;
  c := leapyear mod 400;
  edit2.Text := '不是';                           //根据计算结果进行判断并输出
  if (a=0) and (b<>0) then
    edit2.Text := '是';
  if (b=0) and (c=0) then
    edit2.Text := '是';
end;

end.