why wrong calculation?

Question

unit Unit2;interfaceuses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.StdCtrls,
  FMX.Controls.Presentation, FMX.Edit;type
  TForm2 = class(TForm)
    first: TEdit;
    second: TEdit;
    Button1: TButton;
    third: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form2: TForm2;implementation{$R *.fmx}procedure TForm2.Button1Click(Sender: TObject);
var first:integer;
   second:integer;begin
  third.text:=intToStr(first+second);end;

Answer 1

procedure TForm2.Button1Click(Sender: TObject);
begin
third.text:=inttostr(strtointdef(first.text,0)+strtointdef(second.text,0));
end;

Answer 2

works fine.Thankyou,but it looks like very complicated!

Answer 3

why division doesn't work when I put the (/) instead of(+)?

Answer 4

自己去学习delphi基础吧，多看看别人的代码。不要再问问题了。

Answer 5

在网上搜denphi 运行错误对照表，自己根据提示错误的意思去排查，这样你学到的东西会更扎实······

Answer 6

这是没有一点基础的哈。  first: TEdit;
   second: TEdit;