Overload resolution failed?

Question

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I am having some problems with this line of code

VB

If RegQueryValueEx(hKey, Value, 0, pdwType, Nothing, pvSize) = ERROR_NONE Then

to anyone with knowledge about the registry I would like to know how to correct this line so that it works with my vb.net application.

the variable not listed in the function is

VB

Private Const ERROR_NONE As Integer = &H0

And here it is once more as a full function

VB

Public Function ValueExists(ByVal RootKey As ROOT_KEY, ByVal SubKey As String, ByVal Value As String) As Boolean
           Dim hKey As UIntPtr = UIntPtr.Zero
           Dim pvSize As UInteger = 0
           Dim pdwType As UInteger = CUInt(VALUE_TYPE.REG_NONE)

           Try
               If RegOpenKeyEx(RootKey, SubKey, 0, KEY_QUERY_VALUE, hKey) <> ERROR_NONE Then
                   Return False
               End If
               Return (RegQueryValueEx(hKey, Value, 0, pdwType, Nothing, pvSize) = ERROR_NONE)
           Finally
               If hKey <> UIntPtr.Zero Then
                   RegCloseKey(hKey)
               End If
           End Try
       End Function

I have translated this from C# to vb.net but get the error in full

Error 3 Overload resolution failed because no accessible 'RegQueryValueEx' is most specific for these arguments:
'Public Shared Function RegQueryValueEx(hKey As System.UIntPtr, lpValueName As String, lpReserved As Integer, ByRef lpType As UInteger, ByRef lpData As Byte, ByRef lpcbData As UInteger) As Integer': Not most specific.
'Public Shared Function RegQueryValueEx(hKey As System.UIntPtr, lpValueName As String, lpReserved As Integer, ByRef lpType As UInteger, lpData As System.Text.StringBuilder, ByRef lpcbData As UInteger) As Integer': Not most specific. C:\Users\Admin\Desktop\cLightning.vb 1095 24

Posted 5-Jul-12 18:02pm

Dale 2012

Updated 5-Jul-12 18:08pm

v2

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Comments

Sergey Alexandrovich Kryukov 6-Jul-12 0:14am

Please add to your questions: all declarations of all methods ReqQueryValueEx.
The problem is extremely simple.
--SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2012-07-05T18:34:00

Most likely, the problem is in the parameter Nothing. This is a null pointer, and it's not possible to figure out what type do you imply, because there is more than one method named RegQueryValueEx, and this Nothing can be interpreted as one or another type, because your Nothing might mean any reference.

What to do? I don't know your declarations (please see my comment to the question; is it P/Invoked Windows API? Why?), but you need to use either array of bytes of the instance of StringBuilder. Declare a variable of one and another type, initialize it with Nothing and pass this explicitly defined variable to the method. This is a usual way of resolving such issues.

There are other problems in this code. You return the return result of this method, which is integer, but ValueExists expects Boolean.

However, you don't need that stuff at all. Use the .NET class Microsoft.Win32.Registry and related classes, stop torturing yourself:
http://msdn.microsoft.com/en-US/library/microsoft.win32.registry.aspx[^].

[EDIT #1]

Answering a follow-up question:

Cleaning the registry is not easy and not safe. I would start from finding a good registry repair program. And such program should be the one which can backup all the registry and restore it. As you can screw up the registry to the point where you cannot boot or normally operate your OS, this repair program should boot its own OS from a flash drive or something.

I don't know what exactly to use but 100% sure this is possible. I would start looking from here:
http://en.wikipedia.org/wiki/List_of_data_recovery_software[^],
http://en.wikipedia.org/wiki/List_of_tools_to_create_Live_USB_systems[^],
http://en.wikipedia.org/wiki/System_Restore[^].

It's hard to say where to start with the registry clean up. I have tried only a limited subset of cleaning. For example, you can locate all references to file system objects and detect those pointing to non-existing files/directories. These entries should be eventually removed, but first, you need to walk the registry to remove the entries where the entries you would remove are used and do it all recursively. Again, this is not easy and not safe. Thoroughly plan each step and theoretically calculate possible adverse effects, back up…

[EDIT #2]

Sorry, probably I did not get it: if you not going to modify the registry, you are safe. Anyway, I hope the notes of [EDIT #1] could be useful.

—SA