Does a const instantiation of a custom class make *everything* in the class constant too?

Question

1. How do most compilers actually deal with const? What does it mean technically? (not practically)

When I say everything I mean, suppose I have a custom class with a container as a member field, and then a function that passes by reference values and appends them into that member field.

2. If I have a const instantiation of this class, will constantness filter down?

3. If I have a const STL iterator of a non const container (of my sharedPointers to instantiations of my custom class), what exactly is const about it? Will I be able to alter the contents of the container using the aforementioned function? Will the pointed to data be mutable but nothing else?

Answer 1

1. Off topic for this site.

2. If I have a const instantiation of this class, will constantness filter down? Yes.

3. If I have a const STL iterator of a non const container. If const iterator then you cannot increment or decrement the iterator, but you can use it to modify its referent. If const_iterator then you can increment or decrement it, but you cannot use it to modify its referent. In either case, other non-const iterators to the container may also exist, so the container may be modified by them.