delphi写的简单的文件的打开和关闭  
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delphi写的简单的文件的打开和关闭


unit Unit1;

interface

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

type

TForm1 = class(TForm)
Button1: TButton;
Memo1: TMemo;
Label1: TLabel;
Edit1: TEdit;
Edit2: TEdit;
Label2: TLabel;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
end;
//定义记录类型
TRecEmp = record
//需要初始化
EmpNo: String[20];
EmpName: String[30];
end;

var
Form1: TForm1;
RecEmp: TRecEmp;
//定义一个记录类型的文件变量
FileText: file of TRecEmp;
implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
last: LongInt;
begin
RecEmp.EmpNo := trim(Edit1.Text);
RecEmp.EmpName := trim(Edit2.Text);
try
//和某个文件建立链接
AssignFile(FileText,'d:\sql.txt');
//打开一个已经存在的文件
Reset(FileText);
last := FileSize(FileText);
//将指针移向指定记录
Seek(FileText, last);
//写文件
Write(FileText, RecEmp);
Edit1.Text := '';
Edit2.Text := '';
CloseFile(FileText);
except
ReWrite(FileText);
end;

end;

procedure TForm1.Button2Click(Sender: TObject);
begin
try
AssignFile(FileText,'d:\sql.txt');
Reset(FileText);
while not Eof(FileText) do
begin
//读文件
Read(FileText, RecEmp);
Memo1.Lines.Add(RecEmp.EmpNo + RecEmp.EmpName);
end;
finally
//关闭文件
CloseFile(FileText);
end;
end;

end.

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