注册表

var
  reg:TRegistry;
begin
  reg:=Tregistry.Create;
  reg.RootKey:=HKEY_CURRENT_USER;
    if not reg.KeyExists('/Software/tt/tt') then    //判断是否有主键;
　　begin
       //这里是当不存在要做的程序
    end;
    reg.closekey;
    reg.free;  


判断建值是否存在
if not reg.valueExists('user') then
begin
reg.WriteInteger('user',strtoint(edit1.text));
end;
reg.closekey;
reg.free;
一篇利用注册表给程序加入试用期的列子。

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Edit4: TEdit;
    procedure FormActivate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
{$R *.dfm}

procedure TForm1.FormActivate(Sender: TObject);
var reg:tregistry;  const a=10;
begin
reg:=tregistry.Create;
if not reg.KeyExists('ddd/ddd') then
begin
reg.CreateKey('ddd/ddd');
end;
reg.OpenKey('ddd/ddd',true);
if not reg.valueExists('aaa')then
begin
reg.WriteString('aaa','0');
end;
edit1.Text:=reg.Readstring('aaa');
edit3.Text:=inttostr(strtoint(edit1.Text)+strtoint(edit2.Text));
reg.Writestring('aaa',''+edit3.text+'');
reg.CloseKey;
if a<strtoint(edit3.text) then
showmessage('ddddddd');
end;
end.