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C# Open registry " * " system read error

Hi There! I have a simple program which is to read the recent save files from Windows XP registry. However there is an error upon running the program through the Visual Studio 2010 console mode for c#. The error out put is "Object reference not set to an instance of an Object"

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Win32;

namespace Tracking_Files
{
    class ConsoleApplication1
    {
        static void Main(string[] args)
        {
            try
            {
                RegistryKey rk = Registry.CurrentUser;

                rk = rk.OpenSubKey("Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ComDlg32\\OpenSaveMRU", false);
                PrintKeys(rk);
            }

            catch (Exception MyError)
            {
                Console.WriteLine("An error has occurred: " + MyError.Message);
            }
        }

        static void PrintKeys(RegistryKey rk)
        {
            if (rk == null)
            {
                Console.WriteLine("No specified registry key!");
                return;
            }

            String[] names = rk.GetSubKeyNames();

            Console.WriteLine("Subkeys of " + rk.Name);
            Console.WriteLine("-----------------------------------------------");

            foreach (String s in names)
            {
                Console.WriteLine(s);

                RegistryKey rk2 = Registry.CurrentUser.OpenSubKey("Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ComDlg32\\OpenSaveMRU" + s, false);

                String[] reg = rk2.GetSubKeyNames();

                try
                {
                    if (rk2 == null)
                    {
                        Console.WriteLine("Couldn't open the desired subkey.");
                        return;
                    }

                    Console.WriteLine("Subkeys of " + rk2.Name);
                    Console.WriteLine("-----------------------------------------------");

                    string[] valnames = rk2.GetValueNames();

                    int i = 0;

                    foreach (string k in valnames)
                    {
                        string val = (string)rk2.GetValue(valnames[i++]);
                        Console.WriteLine(k + " contains " + val);
                    }

                    rk.Close();
                }

                catch (Exception MyError)
                {
                    Console.WriteLine("An error has occurred: " + MyError.Message);
                }

                Console.WriteLine("-----------------------------------------------");
            }
        }
    }
}

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I have narrowed down the error to the line :

RegistryKey rk2 = Registry.CurrentUser.OpenSubKey("Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ComDlg32\\OpenSaveMRU" + s, false);

Open in new window


When I add in either Etc. " * "or "docs" instead of "+ s", it works perfectly! So is there anyway that I can let the program/system to understand the "*" is a directory while opening the key?

Thanks!
0
VMthinker
Asked:
VMthinker
  • 4
1 Solution
 
Subrat (C++ windows/Linux)Software EngineerCommented:
In line 44 Rk2 is null, after that forcibly ur tring to get the subkeys So getting exception. Solution might be before proceeding to getting the subkeys, lets check up whether rk2 is null or null!
0
 
Subrat (C++ windows/Linux)Software EngineerCommented:
Typo------>
null or not.
0
 
Subrat (C++ windows/Linux)Software EngineerCommented:
RegistryKey rk2 = Registry.CurrentUser.OpenSubKey("Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ComDlg32\\OpenSaveMRU\\" + s, false);
0
 
Subrat (C++ windows/Linux)Software EngineerCommented:
If want to use single slash '\' then keep the string after @
Ex:
@"Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32\OpenSaveMRU\"


The Complete code is as follows.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Win32;

namespace Tracking_Files
{
    class Program
    {
        const String reg_key = @"Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32\OpenSaveMRU";

        static void Main(string[] args)
        {

            try
            {
                RegistryKey rk = Registry.CurrentUser;

                rk = rk.OpenSubKey(reg_key, false);
                PrintKeys(rk);
            }

            catch (Exception MyError)
            {
                Console.WriteLine("An error has occurred: " + MyError.Message);
            }
        }

        static void PrintKeys(RegistryKey rk)
        {
            if (rk == null)
            {
                Console.WriteLine("No specified registry key!");
                return;
            }

            String[] names = rk.GetSubKeyNames();

            Console.WriteLine("Subkeys of " + rk.Name);
            Console.WriteLine("-----------------------------------------------");

            foreach (String s in names)
            {
                Console.WriteLine(s);

                RegistryKey rk2 = Registry.CurrentUser.OpenSubKey((reg_key + @"\" + s), false);

               
                try
                {
                    if (rk2 == null)
                    {
                        Console.WriteLine("Couldn't open the desired subkey: " +
                                           reg_key + @"\" + s);
                        return;
                    }
                    String[] reg = rk2.GetSubKeyNames();

                    Console.WriteLine("Subkeys of " + rk2.Name);
                    Console.WriteLine("-----------------------------------------------");

                    string[] valnames = rk2.GetValueNames();

                    int i = 0;

                    foreach (string k in valnames)
                    {
                        string val = (string)rk2.GetValue(valnames[i++]);
                        Console.WriteLine(k + " contains " + val);
                    }

                    rk.Close();
                }

                catch (Exception MyError)
                {
                    Console.WriteLine("An error has occurred: " + MyError.Message);
                }

                Console.WriteLine("-----------------------------------------------");
            }

        }
    }
}


0
 
VMthinkerAuthor Commented:
Thanks for the explination! The codes work perfectly!
0
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