v4_1.pas

《Delphi 7经典问题解析》源代码 第一到七章 基础篇源程序 应用篇源程序

unit V4_1;

interface

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

type
  TForm1 = class(TForm)
    btnCreate: TButton;
    btnAppend: TButton;
    btnOpenRead: TButton;
    Memo1: TMemo;
    procedure btnCreateClick(Sender: TObject);
    procedure btnAppendClick(Sender: TObject);
    procedure btnOpenReadClick(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;


var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnCreateClick(Sender: TObject);
var
  MyTextFile: TextFile;
  s: string;
  i: integer;
begin
  //关联文件
  AssignFile(MyTextFile, 'MyTextFile.txt');
  //覆盖或创建新文件
  Rewrite(MyTextFile);
  //向文本文件里写字符串
  try
    for i := 1 to 5 do
    begin
      s := 'This is line #';
      Writeln(MyTextFile, s, i);
    end;
  finally
    CloseFile(MyTextFile);
  end;
end;

procedure TForm1.btnAppendClick(Sender: TObject);
var
  MyTextFile: TextFile;
  s: string;
  i: integer;
begin
  //关联文件
  AssignFile(MyTextFile, 'MyTextFile.txt');
  //判断文件是否存在
  if FileExists('MyTextFile.txt') then
  //以添加的方式打开文本
    Append(MyTextFile)
  else
    raise Exception.Create('MyTextFile.txt不存在');
  //向文本添加字符串
  try
    for i := 6 to 10 do
    begin
      s := 'This is line #';
      Writeln(MyTextFile, s, i);
    end;
  finally
    CloseFile(MyTextFile);
  end;
end;

procedure TForm1.btnOpenReadClick(Sender: TObject);
var
  MyTextFile: TextFile;
  s: string[14];
  i, j: integer;
begin
  //关联文件
  AssignFile(MyTextFile, 'MyTextFile.txt');
  //判断文件是否存在
  if FileExists('MyTextFile.txt') then
  //以只读方式打开文本
    Reset(MyTextFile)
  else
    raise Exception.Create('MyTextFile.txt不存在');
  //读取文本数据
  try
    while not eof(MyTextFile) do
    begin
      Readln(MyTextFile, s, j);
      Memo1.lines.Add(s + IntToStr(j));
    end;
  finally
    CloseFile(MyTextFile);
  end;
end;




end.