Invisible wrote:
> (You knew there were going to be a few at some point...)
> 
> I just want to make sure I've got this absolutely straight in my head. 
> So... a reference is the same as a pointer, except that it has nicer 
> syntax, and you cannot change where it points to?
> 
> If I'm understanding this correctly, a "union" is like several structs 
> with the same base address, and you can treat it was one struct or the 
> other struct, and it's up to you to remember which which struct you're 
> currently using it is. (I.e., the language itself provides no way to 
> distinguish.)
> 
> Here's a perverse question: can a union have member functions?

Yes.

> My understanding is that when you create variables, they start off 
> containing junk unless you initialise them (or their types have 
> constructors which initialise them to something specific). Is that correct?

Yes.

> Does C++ have a concept of a "null pointer" - i.e., a pointer that 
> doesn't point to anything valid, and can be detected as such?

Yes.

> How does memory allocation work in C++? If a program fills the heap, do 
> you have to explicitly *do* something to enlarge the heap, or does it 
> grow automatically? Does it shrink back again after you release things, 
> or do you have to request that manually?

Depends on the implementation.

Regards,
John

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