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This application was as much a .NET forms learning experience as it was looking at how the system Registry is accessed from C# and .NET. The RegistryKey Class is part of the Microsoft Win32 class. This version of the application only lists the SubKeys and their values. There are also methods for adding, deleting, and modifying a SubKey, as well as deleting a SubKey tree. I have not finished these functions in this release.

//-------------------------------------------------------------
// a subkey has been clicked upon.
// Display the subkey's subkeys and values
private void SubkeyListBoxIndexChanged(object sender,
                                       System.EventArgs e)
{
  String newkey =  m_subkey_list.SelectedItem.ToString();
  if (m_current_key.Text.Length == 0) m_current_key.Text = newkey;
  else
  m_current_key.Text =m_current_key.Text + "\\" + newkey;
  GetKeysAndValues();
}
//---------------------------------------------------------
// This routine is invoked when the up arrow is clicked on.
// It takes the listing to the nest higher level.
private void UpButtonClick(object sender, System.EventArgs e)
{
  String new_key = m_current_key.Text;
  int nDx        = new_key.LastIndexOf('\\');
  if (nDx == -1)   m_current_key.Text = "";
  else             m_current_key.Text = new_key.Substring(0,nDx);
  GetKeysAndValues();
}
//----------------------------------------------------------
private void RootKeyComboboxIndexChanged(object sender,
                                         System.EventArgs e)
{
  m_root_key_listbox.Text = m_root_key_listbox.SelectedItem.
                                               ToString();
  m_current_key.Text = "";        //we're at the root
   GetKeysAndValues();            //get top-level keys
}
//-------------------------------------------------------
void GetKeysAndValues()
{
  RegistryKey rkey =  GetSelectedKey();
try
{
  m_root_key_listbox.Text = rkey.Name.ToString();
  int nDx      = m_root_key_listbox.Text.IndexOf('\\');
  if (nDx != -1) m_root_key_listbox.Text = rkey.
                                           Name.Substring(0,nDx);

  m_subkey_list.Items.Clear();
  string[] sknames = rkey.GetSubKeyNames();
  foreach(String str in sknames ) {
    String vstring = (String) rkey.GetValue
                     (str, typeof(string).ToString());
    m_subkey_list.Items.Add(str);
  }
  m_status.Text = "OK";
  DisplayTypesAndValues(rkey);
  rkey.Close();
}
  catch (Exception except)
  {
  m_status.Text = "Exception occurred " + except.Message;
  }
}
//------------------------------------------------------
RegistryKey GetSelectedKey()
{
  RegistryKey rkey =  null;
try
{
  int nDx = m_root_key_listbox.SelectedIndex;
  switch (nDx)
  {
  case 0:
    rkey = Registry.ClassesRoot.OpenSubKey(m_current_key.Text);
    break;
  case 1:
    rkey = Registry.CurrentConfig.OpenSubKey(m_current_key.Text);
    break;
  case 2:
    rkey = Registry.CurrentUser.OpenSubKey(m_current_key.Text);
    break;
  case 3:
    rkey = Registry.LocalMachine.OpenSubKey(m_current_key.Text);
    break;
  case 4:
    rkey = Registry.Users.OpenSubKey(m_current_key.Text);
    break;
  default:
    break;
  }
}
  catch (Exception except)
  {
  m_status.Text = "Exception occurred " + except.Message;
  }
    return rkey;
}
//-------------------------------------------------------
void DisplayTypesAndValues(RegistryKey rkey)
{
  listView1.Items.Clear();
  string[] SubKeys  = rkey.GetValueNames();
  foreach(String vstr in SubKeys ) {    //subkey value name
    object robj =  rkey.GetValue(vstr, typeof(string));
    String vstring  = "";
    String vtype    = "";
    GetTypeAndValue(robj, ref vtype, ref vstring);
    ListViewItem item1 = new ListViewItem();
    if (vstr == "" ) item1.Text= "Default";
    else             item1.Text= vstr;

    listView1.Items.Add(item1);
    item1.SubItems.Add(vtype);
    item1.SubItems.Add(vstring);
  }
}
//-------------------------------------------------------
void GetTypeAndValue(object robj, ref String Type,
                                  ref String Value)
{
  Value  = robj.ToString();             //get object value
  Type    = robj.GetType().ToString();  //get object type
  Type    = Type.Substring(7, Type.Length-7);
                                        //strip off "System."
  //check if special formatting is necessary
  if (Type == "Byte[]") {
    Value = "";
    byte[] Bytes = (byte[]) robj;
    foreach(byte bt in Bytes) {
      string hexval = bt.ToString();
      if (hexval == "") hexval = "0";
      Value         = Value + hexval+ " ";
    }
  }
}
//-----------------------------------------------------

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