mainunit.pas

《Delphi 7经典问题解析》源代码 第一到七章 基础篇源程序 应用篇源程序

unit mainunit;

interface

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

type
  IntegerProc = procedure (Var Number: Integer);
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    GroupBox1: TGroupBox;
    RadioButton1: TRadioButton;
    RadioButton2: TRadioButton;
    Edit1: TEdit;
    Label1: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
    OneIntProcInstance: IntegerProc;
    Number: Integer;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
procedure TripleTheValueProc (Var Value: Integer);
begin
  Value := Value * 3;
  ShowMessage ('The initail Value is tripled! Now it is:' + IntToStr (Value)+'.');
end;

procedure DoubleTheValuePorc (Var Value: Integer);
begin
  Value := Value * 2;
  ShowMessage ('The initail Value is doubled! Now it is:' + IntToStr (Value)+'.');
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 Number:=0;
 RadioButton1.Checked:=True;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
 if (Edit1.Text='') then
  begin
   Showmessage('请先在编辑框中输入初始数值，然后选择操作类型后再点击这个按钮!');
   Edit1.SetFocus;
  end
  else
  begin
   if (RadioButton1.Checked) then
    begin
      Number:=StrToInt(Edit1.Text);
      OneIntProcInstance:=DoubleTheValuePorc;
      OneIntProcInstance(Number);
    end
    else
    begin
     Number:=StrToInt(Edit1.Text);
     OneIntProcInstance:=TripleTheValueProc;
     OneIntProcInstance(Number);
    end;
  end;
end;

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

end.