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Question

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;type
  TForm1 = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Button1: TButton;
    Label5: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Edit4: TEdit;
    Edit5: TEdit;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.FormCreate(Sender: TObject);
begin
edit1.Text:='';
edit2.Text:='';
edit3.Text:='';  
edit4.Text:='';
edit5.Text:='';
end;procedure TForm1.Button1Click(Sender: TObject);
begin
if edit1.Text:=''
then showmessage('sadf'); '为什么这一句老报错，消息框弹不出？end;end.

Answer 1

呵呵,IF语句中能赋值吗?
应该是
IF EDIT1.TEXT='' then
showmessage('sadf');
end;
end.

Answer 2

if edit1.text = '' then
  showmessage('error');

Answer 3

if edit1.text='' then 
   showmessage('nill');