Does an instance method not create an object reference in c#

Question

I'm working on an asp.net web application in c#. I have a public class called GetUser. In that class I have a method called GetCurrentUser. The method is as follows:

    public MobileUser GetCurrentUser(MDMDataContext dc, string userCode)
    {
        using (dc)
        {
            dc.ObjectTrackingEnabled = false;
            var currentUser =
                from MobileUser in dc.MobileUsers
                where MobileUser.UserCode == usercode                     
                select MobileUser;

            MobileUser mu = new MobileUser();
            mu = currentUser.Single();

            return mu;
        }
    }

But when I try to use the GetCurrentUser instance method as follows:

using (MDMDataContext dc = new MDMDataContext())
        {
            GetUser.GetCurrentUser(dc, "ABCD");
        }

I get the following error, "An object reference for the non-static field, method or property '....GetUser.GetCurrentUser....'

But if I add the static keyword to the function, the error goes away. Can somebody please demystify this concept for me?

Answer 1

Your method is an instance method, which means you need an instance on which to run it:

using (MDMDataContext dc = new MDMDataContext())
{
        GetUser user = new GetUser();
        user.GetCurrentUser(dc, "ABCD");
}

The static keyword means that the method is static, and available for the type as a whole, not tied to a specific instance. That's why you can call it using the class name (and must call it that way) when it's marked static.