TRegistry.CloseKey Method

Writes the current key to the registry and closes the key.

Pascal

procedure CloseKey;

C++

__fastcall CloseKey();

Description

Call CloseKey to write the current key to the registry and close the key. An application should not keep keys open any longer than necessary. Many TRegistry methods routinely call CloseKey after reading from or writing to the registry. Calling CloseKey when there is no current key has no effect.

Note: When an application closes a key, the key is written to the registry. The LazyWrite property determines how the write takes place.

C++ Examples:

Copy Code

/*
This example shows how to use the TRegistry class in order to
find, insert and delete Keys and Items into the Windows Registry.
This example uses two buttons: InsertToRegBtn and DeleteFromRegBtn,
for inserting and deleting the values.
*/
void __fastcall TForm2::InsertToRegBtnClick(TObject *Sender)
{
    TRegistry* reg = new TRegistry(KEY_READ);
    reg->RootKey = HKEY_LOCAL_MACHINE;

    if(!reg->KeyExists("Software\\MyCompanyName\\MyApplication\\"))
    {
        MessageDlg("Key not found! Created now.",
                    mtInformation, TMsgDlgButtons() << mbOK, 0);
    }
    reg->Access = KEY_WRITE;
    bool openResult = reg->OpenKey("Software\\MyCompanyName\\MyApplication\\", true);

    if(!openResult)
    {
        MessageDlg("Unable to create key! Exiting.",
                    mtError, TMsgDlgButtons() << mbOK, 0);
        return;
    }
    //checking if the values exist and inserting when neccesary

    if(!reg->KeyExists("Creation\ Date"))
    {
        TDateTime today = TDateTime::CurrentDateTime();
        reg->WriteDateTime("Creation\ Date", today);
    }

    if(!reg->KeyExists("Licenced\ To"))
    {
        reg->WriteString("Licenced\ To", "MySurname\ MyFirstName");
    }

    if(!reg->KeyExists("App\ Location"))
    {
        reg->WriteExpandString("App\ Location",
                                "%PROGRAMFILES%\\MyCompanyName\\MyApplication\\");
    }

    if(!reg->KeyExists("Projects\ Location"))
    {
        reg->WriteExpandString("Projects\ Location",
                                "%USERPROFILE%\\MyApplication\\Projects\\");
    }

    reg->CloseKey();
}
//---------------------------------------------------------------------------
void __fastcall TForm2::DelFromRegBtnClick(TObject *Sender)
{
    //deleting the example registry entries
    TRegistry* reg = new TRegistry(KEY_WRITE);
    reg->RootKey = HKEY_LOCAL_MACHINE;

    reg->DeleteKey("Software\\MyCompanyName\\MyApplication");
    reg->DeleteKey("Software\\MyCompanyName");

    reg->CloseKey();
}
//---------------------------------------------------------------------------

Delphi Examples:

Copy Code

{
This example shows how to use the TRegistry class in order to
find, insert and delete Keys and Items into the Windows Registry.
This example uses two buttons: InsertToRegBtn and DeleteFromRegBtn,
on a form, for inserting and deleting the values.
}
procedure TForm3.InsertToRegBtnClick(Sender: TObject);
var
  reg        : TRegistry;
  openResult : Boolean;
  today      : TDateTime;
begin
  reg := TRegistry.Create(KEY_READ);
  reg.RootKey := HKEY_LOCAL_MACHINE;

  if (not reg.KeyExists('Software\\MyCompanyName\\MyApplication\\')) then
    begin
      MessageDlg('Key not found! Created now.',
                            mtInformation, mbOKCancel, 0);
    end;
  reg.Access := KEY_WRITE;
  openResult := reg.OpenKey('Software\\MyCompanyName\\MyApplication\\',True);

  if not openResult = True then
    begin
      MessageDlg('Unable to create key! Exiting.',
                  mtError, mbOKCancel, 0);
      Exit();
    end;

  {checking if the values exist and inserting when neccesary}

  if not reg.KeyExists('Creation\ Date') then
    begin
      today := Now;
        reg.WriteDateTime('Creation\ Date', today);
    end;

  if not reg.KeyExists('Licenced\ To') then
    begin
        reg.WriteString('Licenced\ To', 'MySurname\ MyFirstName');
    end;

  if not reg.KeyExists('App\ Location') then
    begin
        reg.WriteExpandString('App\ Location',
                            '%PROGRAMFILES%\\MyCompanyName\\MyApplication\\');
    end;

  if not reg.KeyExists('Projects\ Location') then
    begin
        reg.WriteExpandString('Projects\ Location',
                            '%USERPROFILE%\\MyApplication\\Projects\\');
    end;

  reg.CloseKey();

end;

procedure TForm3.DeleteFromRegBtnClick(Sender: TObject);
var
  reg : TRegistry;
begin
  reg := TRegistry.Create(KEY_WRITE);
  reg.RootKey := HKEY_LOCAL_MACHINE;

  reg.DeleteKey('Software\\MyCompanyName\\MyApplication');
  reg.DeleteKey('Software\\MyCompanyName');

  reg.CloseKey();
end;