Registry Test

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Environment: C Sharp

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.

One thing to note, SubKeys are not case sensitive. This particular program taught me more about the forms interface and C# programming than any other I’ve done so far. Multi-column ListBoxes and C# were new to me. It is a working but incomplete program. I was going to add add/modify/delete functions, but I didn’t have the spare time. When I need the functions, I’ll write them and post them. The following is the main part of the application. We start listing the subkeys of HKEY_CURRENT_USER. Clicking on a subkey lists that subkey’s subkeys and values. Clicking on the up arrow removes a level of the tree and displays the new key.

//-------------------------------------------------------------
// 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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