Question

I’m new to C#. I wonder why I get errors for this:

Error: For this method a Object-Reference is necessary (translated from the German Message). Any Ideas. Seems to be correct for me.

namespace DNS
{

    public class Core
    {

        Dig dig;

        public Core()
        {
            dig = new Dig();
        }


        public static void startTest()
        {
            dig.myServer = "10.10.10.10"; <------ ERROR

Answer 1

You are trying to access the instance dig field in a static method which is not possible because you need an instance of an object in order to access instance members.

One possibility is to make the dig field static:

public class Core
{
    private static Dig dig = new Dig();

    public static void startTest()
    {
        dig.resolver.DnsServer = "10.10.10.10";
        ...
    }
}

Another possibility is to make the startTest method and instance method:

public class Core
{
    private Dig dig;

    public Core()
    {
        dig = new Dig();
    }

    public void startTest()
    {
        dig.resolver.DnsServer = "10.10.10.10";
        ...
    }
}

or yet another possibility is to create an instance of the Core object in the static method:

public class Core
{
    private Dig dig;

    public Core()
    {
        dig = new Dig();
    }

    public static void startTest()
    {
        Core core = new Core();
        core.dig.resolver.DnsServer = "10.10.10.10";
        ...
    }
}

It will depend on your actual design requirements.