处理之文本文件

unit Unit1;

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
Button3: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

var
F: TextFile;
FileName: string = 'c:/A.txt';

{$R *.dfm}

//向文本文件写入内容
procedure TForm1.Button1Click(Sender: TObject);
begin
AssignFile(F,FileName);
Rewrite(F);        //重写(覆盖)已存在的文件
Writeln(F,'one');  //写入一行
Writeln(F,'two');
CloseFile(F);
end;

//读取文本文件内容
procedure TForm1.Button2Click(Sender: TObject);
var
str:string;
begin
AssignFile(F,FileName);
Reset(F);         //以只读方式打开文本文件
while not Eof(F) do      //循环文本文件,判断是否到尾部
begin
Readln(F,str);         //读取一行
ShowMessage(str);
end;
end;

//向文本文件追加内容
procedure TForm1.Button3Click(Sender: TObject);
begin
AssignFile(F,FileName);
Append(F);              //打开文件准备追加,指针指向文本末尾
Writeln(F, 'three');   //写入一行
Writeln(F, 'four');
CloseFile(F);
end;

end.