Add an object list to itself?

Question

I was wondering what would happen if I added a list to itself. Maybe a stack overflow, maybe a compiler error?

List<object> lstobj = new List<object>();
lstobj.Add(lstobj);

So I executed the code and checked the local variables:

The list seems to contain an infinite number of list instances. Why is there no stack overflow? Are the lists just pointers to the original list? But even if the lists are just pointers, do pointers not also occupy memory too?

Answer 1

It would not be a problem. List is reference type, i.e., you will get a reference to the list inside itself (exactly what you showed).

So what you see (that big hierarchy) is only in Visual Studio. The real situation is just you get a reference to the memory address of that array inside the same memory address of the same array. Therefore, you get stack overflow.

You would see that a lot in Navigation properties when using Entity framework.

It would be a problem if you tried to serialize the list without configuring the serializer to be aware when serializing the circular references.