What does the {???} mean in the VC++ Watch window?

Question

I am debugging a C project with Visual Studio 2013. What does the {???} mean in the below Watch window?

I guess there must be something wrong and I searched a bit. But no luck.

Answer 1

Igor’s suggestion is correct, this is the sample for this issue.

If I disable the line code “currnode->nextnode = NULL;”, it will show the same result as yours.

But if I enable it, it would show the NULL value like this screen shot, so it would be related to null value of the pointer.