Question

I’m a beginner in programming. I wrote a script to set DNS setting using VB. I was able to set the primary address.

However, I don’t know how to set the secondary address because it will require the use of array.

How can this be done?

Dim DNS As String() = {"192.168.1.1", "192.168.1.2"}

Dim objMC As ManagementClass = New ManagementClass("Win32_NetworkAdapterConfiguration")
Dim objMOC As ManagementObjectCollection = objMC.GetInstances()

For Each objMO As ManagementObject In objMOC
    If (Not CBool(objMO("IPEnabled"))) Then
        Continue For
    End If

    Try
        Dim objSetIP As ManagementBaseObject = Nothing
        Dim objNewDNS As ManagementBaseObject = Nothing
        objNewDNS = objMO.GetMethodParameters("SetDNSServerSearchOrder")

        'Set DNS to DHCP
        objNewDNS("DNSServerSearchOrder") = New String() {DNS()}
        objSetIP = objMO.InvokeMethod("SetDNSServerSearchOrder", objNewDNS, Nothing)
        Console.WriteLine("Updated IPAddress, SubnetMask and Default Gateway!")
    Catch ex As Exception
        MessageBox.Show("Unable to Set IP : " & ex.Message)
    End Try
Next objMO

Answer 1

In VB.Net the Dim keyword is actually short for Dimension and can be used for declaring arrays.

Simply apply brackets to the variable or type and hey presto you have an array.

Dim arrayOfString As String()

Or

Dim arrayOfString() As String

Of course, its a little more complicated than that. You may want to declare your array with a predefined number of elements, say 5, assuming Option Base 0.

Dim arrayOfInt(4) As Int

Or you might want to assign your array with a number of predefined values.

Dim arrayofInt As Int() = {1, 2, 3, 4, 5}

You can also use this syntax,

Dim arrayOfStrings = New String() {"1.2.3.4", "5.6.7.8"}

for instance. Your example,

Dim DNS As String() = {"192.168.1.1", "192.168.1.2"} 

seems perfectly valid.

In your example you have the misforstune to be using WMI. I see you want to invoke the "SetDNSServerSearchOrder" method on the "Win32_NetworkAdapterConfiguration" class.

The objNewDNS = objMO.GetMethodParameters("SetDNSServerSearchOrder") sets objNewDNS to a ManagementBaseObject that is a collection of parameters for the "SetDNSServerSearchOrder" method.

The "SetDNSServerSearchOrder" takes one parameter called "DNSServerSearchOrder" as described here which happens to be an array of strings.

So unless I’m mistaken, and assuming the string array DNS is your search order, your code should read:

'Set DNS to DHCP         
objNewDNS("DNSServerSearchOrder") = DNS 
objMO.InvokeMethod("SetDNSServerSearchOrder", objNewDNS)

note that this code discards the return value of the method call.

EDIT:

From your comments it seems that the object returned by the objMO.InvokeMehtod call is actually a ManagementBaseObject. This wraps the “returnValue” of the invoked method. So somthing like the code below will help you get to the return value, if necessary.

'Set DNS to DHCP         
objNewDNS("DNSServerSearchOrder") = DNS 
Dim oResult As ManagementBaseObject = _
    objMO.InvokeMethod("SetDNSServerSearchOrder", objNewDNS)
Dim result As Integer = CType(oResult["returnValue"], Integer)

So your problems are not related to your ability to declare arrays but rather the tedious interface to WMI. I guess you might need a few more calls for your console output to be entirely valid but I hope this helps you out.