main.~pas

Delphi7数据库开发教程,包含该书21套实例

unit main;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    edtResult: TEdit;
    GroupBox1: TGroupBox;
    GroupBox2: TGroupBox;
    btnConvert: TButton;
    btnHandleConvert: TButton;
    btnTryExcept: TButton;
    btnCatchException: TButton;
    btnDefaultException: TButton;
    procedure btnConvertClick(Sender: TObject);
    procedure btnHandleConvertClick(Sender: TObject);
    procedure btnTryExceptClick(Sender: TObject);
    procedure btnCatchExceptionClick(Sender: TObject);
    procedure btnDefaultExceptionClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnConvertClick(Sender: TObject);
var in1,in2:integer;
begin
  in1 := StrToInt(Edit1.Text);
  in2 := StrToInt(Edit2.Text);
  edtResult.Text := IntToStr(in1 + in2);
end;

procedure TForm1.btnHandleConvertClick(Sender: TObject);
var in1,in2:integer;
begin
  in1 := 0;
  in2 := 0;
  try
    //保护容易出现问题的代码
    in1 := StrToInt(Edit1.Text);
    in1 := StrToInt(Edit2.Text);
  finally
    //不管是否出现异常，都会在edtResult中显示结果
    edtResult.Text := IntToStr(in1 + in2);
  end;
end;

procedure TForm1.btnTryExceptClick(Sender: TObject);
var in1,in2:integer;
begin
  try
    //保护容易出现问题的代码
    in1 := StrToInt(Edit1.Text);
    in1 := StrToInt(Edit2.Text);
    edtResult.Text := IntToStr(in1 + in2);
  except
    //只有出现异常时显示提示信息
    edtResult.Text := '无法完成计算，请检查输入的值的类型';
  end;
end;

procedure TForm1.btnCatchExceptionClick(Sender: TObject);
var in1,in2:integer;
begin
  try
    //保护容易出现问题的代码
    in1 := StrToInt(Edit1.Text);
    in1 := StrToInt(Edit2.Text);
    edtResult.Text := IntToStr(in1 + in2);
  except
    //只有出现异常时显示提示信息
    on E: EConvertError do
       begin
         edtResult.Text := E.Message ;
       end;
  end;
end;

procedure TForm1.btnDefaultExceptionClick(Sender: TObject);
var in1,in2,ret:integer;
begin
  try
    //保护容易出现问题的代码
    in1 := StrToInt(Edit1.Text);
    in1 := StrToInt(Edit2.Text);
    ret := in1 * in2 *in1 * in2;
    edtResult.Text := IntToStr(ret);
  except
    //只有出现异常时显示提示信息
    on E: EConvertError do
       begin
         edtResult.Text := E.Message ;
       end;
    else
       edtResult.Text := '无法完成计算，请检查输入的值的类型';
  end;
end;

end.