Handbook之011：预设参数

Delphi函数声明可以写预设参数，定义的时候，可以不用写

代码如下：

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

//函数声明
procedure ShowOnMemo (Msg: string; Caption: string = '信息'; Separator: string = ': ');

implementation

{$R *.dfm}

//函数定义
procedure ShowOnMemo (Msg: string; Caption: string ; Separator: string );
begin
   Form1.Memo1.Lines.Add(Caption + Separator + Msg);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowOnMemo('曾经沧海难为水');
end;

end.