Can I move an object to a given address?

[moonman239]

Suppose I have a class called "Person" Each "Person" has neighbors - represented by a collection - whose house addresses are the physical addresses within memory on the heap. If one person moves to a new address, another person immediately takes their place. How do I make such a move happen in code?

Suppose, for example, that Amy has two neighbors, Bob and Carol. Bob moves out and Dan is to move in. As a result, Amy's neighbor collection should now point to Dan when we give it a key or index related to Bob's old house.

[moonman239]

I've played around with the memmove function today. I found that when I do something like this:

Person *bob = new Person();
bob->name = "Bob";
Person *dan = new Person();
dan->name = "Dan";
memmove(bob,dan,sizeof(Person));
cout << bob->name;

what the program does is print Dan's name instead of Bob's.

[LB]

In general you should never care about the actual address of an object in memory. However, you could use the move assignment operator:
http://en.cppreference.com/w/cpp/language/move_assignment
You shouldn't need to, though.

[cire]

memmove doesn't play nice with C++ objects.

If your name member is a std::string you have undefined behavior.

If you find yourself wanting to move an object to a particular address, there is likely a problem with your design.

For this particular case, a swap would probably be appropriate.

http://en.cppreference.com/w/cpp/algorithm/swap

[moonman239]

cire:

I wrote the following code for a basic conversion from one user-defined class to another. However, the compiler complained that there is "no matching function for call to 'swap'".

struct AnimalConverter {
    template <typename destType> static void convert(Animal *_animal)
    {
        destType *newAnimal = new destType();
        newAnimal->name = _animal->name;
        swap(_animal, newAnimal);
        delete newAnimal;
    }
};

[cire]

I wrote the following code for a basic conversion from one user-defined class to another.

This is a different use-case than the one presented in the OP. Swapping isn't appropriate here. That entire function looks questionable. Don't gratuitously use new.

[ne555]

a Person lives in a House
a House has an Address
a House has bordering Houses
a Person can move out