菜鸟求助,请教各位老师帮忙改一下22课的源码!

学习中-2

  22课的源码我下载后一直没改好,请给为老师看看,为什么不能交换呢?

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Swap_fun(str_a:String;str_b:String);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  str1: String;
  str2: String;
  temp: String;


begin
  str1:= Edit1.Text;
  str2:= Edit2.Text;

  Swap_fun(str1, str2);
  Edit1.Text:= str1;
  Edit2.Text:= str2;
end;

procedure TForm1.Swap_fun(str_a:String; str_b:String);
var
  temp:string;
begin
  temp:= str_a;
  str_a:= str_b;
  str_b:= str_a;
end;

end.

学习中-2

原来是自己看教程没认真,少了个Var,:(