TRegistry

// For next example
// Just read language from regestry
  GetLocaleInfo( LOCALE_SYSTEM_DEFAULT, LOCALE_SENGLANGUAGE, @LocaleStr, sizeof(LocaleStr) );

the easiest is to use the TRegIniFile. This is a wrapper around TRegistry in such a way that it looks like you're writing to an inifile (thus old programs saving to an ini-file can easely be changed to saving the registry) see regini example in help file!

unit reginid;

interface

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

type
  TRegIniForm = class(TForm)
    GroupBox1: TGroupBox;
    Label1: TLabel;
    CheckBox_Write: TCheckBox;
    RadioGroup_Write: TRadioGroup;
    Edit_Write: TEdit;
    GroupBox2: TGroupBox;
    Label3: TLabel;
    CheckBox_Read: TCheckBox;
    RadioGroup_Read: TRadioGroup;

    Edit_Read: TEdit;
    Memo_Read: TMemo;
    Button_Write: TButton;
    Button_Read: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button_WriteClick(Sender: TObject);
    procedure Button_ReadClick(Sender: TObject);
    procedure CheckBox_ReadClick(Sender: TObject);
    procedure RadioGroup_ReadClick(Sender: TObject);
  private
    { Private declarations }
    procedure Read_Registry;

    procedure Write_Registry;
  public
    { Public declarations }
    FIniFile: TRegIniFile;
  end;

var
  RegIniForm: TRegIniForm;

implementation

{$R *.DFM}

const
  SECTION = 'Sample';

procedure TRegIniForm.FormCreate(Sender: TObject);
begin
  FIniFile := TRegIniFile.Create('Sample Registry');
end;

procedure TRegIniForm.FormDestroy(Sender: TObject);
var
  Cleanup: TRegistry;

  key: string;
begin
  key := FIniFile.FileName;
  FIniFile.Free;

  // make sure we don't leave junk in the registry behind.
  Cleanup := TRegistry.Create;
  try
    Cleanup.DeleteKey(key);
  finally
    Cleanup.Free;
  end;
end;

procedure TRegIniForm.Write_Registry;
begin
  FIniFile.WriteBool(SECTION, 'BooleanTest', CheckBox_Write.Checked);
  FIniFile.WriteInteger(SECTION, 'IntegerTest', RadioGroup_Write.ItemIndex);

  FIniFile.WriteString(SECTION, 'StringTest', Edit_Write.Text);

  if not Button_Read.Enabled then Button_Read.Enabled := True;
end;

procedure TRegIniForm.Read_Registry;
begin
  CheckBox_Read.Checked := FIniFile.ReadBool(SECTION, 'BooleanTest', False);
  RadioGroup_Read.ItemIndex := FIniFile.ReadInteger(SECTION, 'IntegerTest', 0);
  Edit_Read.Text := FIniFile.ReadString(SECTION, 'StringTest', '');

  Memo_Read.Lines.Clear;

  FIniFile.ReadSectionValues(SECTION, Memo_Read.Lines);

  Button_Read.Enabled := False;
end;

procedure TRegIniForm.Button_WriteClick(Sender: TObject);
begin
  Write_Registry;
end;

procedure TRegIniForm.Button_ReadClick(Sender: TObject);
begin
  Read_Registry;
end;


procedure TRegIniForm.CheckBox_ReadClick(Sender: TObject);
begin
  Read_Registry;
end;

procedure TRegIniForm.RadioGroup_ReadClick(Sender: TObject);

begin
  Read_Registry;
end;

end.

Regards, Zif.

Read :

with TRegistry.Create do begin
    RootKey := HKEY_LOCAL_MACHINE; { HKEY_CURRENT_USER by default }
    if OpenKey('Software\Microsoft\Windows\help', false) then begin
      ShowMessage(ReadString('Dao35.hlp'));
      CloseKey;
    end;
    Free;
  end;

Write :

procedure TForm1.Button1Click(Sender: TObject);
var
  reg : TRegistry;
begin
  reg := TRegistry.Create;
  reg.RootKey := HKEY_USERS; { set root }
  reg.OpenKey('geo',true);   { open a key or create it }
  reg.WriteInteger('gInt',123456); { write unsigned DWORD }
  reg.WriteBool('gBool',true);
  reg.WriteFloat('gFloat',123456.34); { write binary data }
  reg.Free;
end;

Regards, Geo

//Read
procedure TForm1.Button1Click(Sender: TObject);
var
  myreg : treginifile;
  S1 : String;
begin
 MyReg := TregIniFile.create('');
 MyReg.RootKey := Hkey_Local_Machine;
 s1 := MyReg.ReadString('Test', 'Dark_king', '');
 myreg.free;
 edit1.Text:= s1;
end;

//Write
procedure TForm1.Button2Click(Sender: TObject);
 var
 Reg: TRegistry;
 adregtext: String;
begin
 Reg := TRegistry.Create;
  adregtext :='\Test';  //  HKEY_LOCAL_MACHINE\Test
  try
    Reg.RootKey := HKEY_LOCAL_MACHINE;
    if Reg.OpenKey(adregtext, True)
        then Reg.WriteString('Dark_king','Hear it is');
  finally
    Reg.CloseKey;
    Reg.Free;
    end;
end;

In your questions you want to read the KEY not the VALUE in register
So if you want to read key it can bee more an  one key
This example read all keys under
HKEY_LOCAL_MACHINE\Config\0001\System\CurrentControlSet\Control\Print\Printers


procedure TForm1.Button1Click(Sender: TObject);
var
Reg3: TRegistry;
deltext: String;
Val:TStringList;
  I: Integer;
      j:String;
begin
   deltext :='\Config\0001\System\CurrentControlSet\Control\Print\Printers';
  Reg3 := TRegistry.Create;
  try

    Reg3.RootKey := HKEY_LOCAL_MACHINE;
    if  Reg3.OpenKey(deltext,False) then
      Val:=TStringList.Create;
      reg3.GetKeyNames(Val);
       for I:=0 to Val.Count-1 do
         begin
          j:=Val.Strings[I]   ;

           ListBox1.items.Add(Val.Strings[I]) ;
         end;
           finally
  Val.Free;
  Reg3.CloseKey;
  Reg3.Free;
    inherited;
    end;
end;

Thanks