unit1.pas

《delphi深度编程及其项目开发》

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    btnRead: TButton;
    btnWrite: TButton;
    procedure btnReadClick(Sender: TObject);
    procedure btnWriteClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnReadClick(Sender: TObject);
var
  UnTypedFile: file;
  Buffer: array[0..127] of Byte;
  NumRead: Integer;
begin
  AssignFile(UnTypedFile, 'MyFile.dat');
  Reset(UnTypedFile);
  try
    {打开MyFile.dat，将128个字节的数据块移到缓冲区Buffer中}
    BlockRead(UnTypedFile, Buffer, 1, NumRead);
  finally
    CloseFile(UnTypedFile);
  end;
end;



procedure TForm1.btnWriteClick(Sender: TObject);
var
  UnTypedFile: file;
  Buffer: array[0..127] of Byte;
  NumWrite: integer;
begin
  AssignFile(UnTypedFile, 'MyFile.dat');
  //如果文件不存在，就新建一个文件，否则，打开该文件并允许读写操作
  if FileExists('MyFile.dat') then
    Reset(UnTypedFile)
  else
    ReWrite(UnTypedFile);
  try
    //将文件指针置于文件末尾
    Seek(UnTypedFile, FileSize(untypedFile));
    FillChar(Buffer, Sizeof(Buffer), 'Y');
    BlockWrite(UnTypedFile, Buffer, 1, NumWrite);
  finally
    CloseFile(UnTypedFile);
  end;
end;

end.