Retrieve value from Registry

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I have c# application which include code to retrieve registry values and check it's values.registry values stored in following manner:

MainKey:
Name:user123
Isregistered:no

however if Isregistered returns no,it will display appropriate message.
i am getting error like this:---

Object reference not set to an instance of an object.

C# Code:

C#

RegistryKey se =  Registry.CurrentUser.OpenSubKey(@"MainKey", true);
           string currentKey;
            currentKey = reg.GetValue("Isregistered", true).ToString();
           if (currentKey == "Yes")
           {
               Console.WriteLine(currentKey.ToString());

           }
           else
           {
               Console.WriteLine(currentKey.ToString());
    }

i am getting error on currentKey =reg.GetValue("Isregistered", true).ToString();

Posted 3-Jan-12 0:45am

sharadpanwal

Updated 3-Jan-12 0:47am

v3

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3 solutions

Solution 2

you can pass Isregistered value in Read method for access Registry value as

Read("Isregistered ");

have a look at method declaration

public string Read(string KeyName)
{
    // Opening the registry key
      RegistryKey rk = baseRegistryKey ;
    // Open a subKey as read-only

    RegistryKey sk1 = rk.OpenSubKey(subKey);
    // If the RegistrySubKey doesn't exist -> (null)

    if ( sk1 == null )
    {
        return null;
    }
    else
    {
        try 
        {
       // If the RegistryKey exists I get its value or null is returned.        
         return (string)sk1.GetValue(KeyName.ToUpper());
        }
        catch (Exception e)
        {
            ShowErrorMessage(e, "Reading registry " + KeyName.ToUpper());
            return null;
        }
    }
}

Reference Link :- Read Registry using C#[^]

Posted 3-Jan-12 1:04am

RaviRanjanKr

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OriginalGriff · Accepted Answer · 2012-01-03T01:00:00

The problem is that it could be either part of that:

C#

reg.GetValue("Isregistered", true)

reg could be null - you don't show it being defined or initialised

reg.GetValue("Isregistered", true).ToString()

If reg is ok, then GetValue could be returning null.
Or, it could be in your GetValue method itself.

Break it up, and single step throung in the debugger:

C#

if (reg != null)
    {
    object o = reg.GetValue("Isregistered", true);
    currentKey = o.ToString();
    }

Then you stand a chance of working out which is causing the problem.

sharadpanwal · Accepted Answer · 2012-01-03T01:21:00

i got solution.Thanks for help.

RegistryKey reg =  Registry.CurrentUser.OpenSubKey(@"MainKey", true);
            string currentKey;
             
             if (reg != null)
             {
                 RegistryKey rKey = reg.OpenSubKey("Isregistered", true);
                 object o = rKey.GetValue("Isregistered");
                 currentKey = o.ToString();
                 
           
                Console.WriteLine(currentKey.ToString());
              }

Retrieve value from Registry

3 solutions

Solution 1

Solution 2

Solution 3

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