How is the memory layout of a class vs. a struct

Question

I come from C programming where the data in a struct is laid out with the top variable first, then the second, third and so on..

I am now programming in C++ and I am

Answer 1

First thing first: class and struct in C++ are very much the same - the only difference is that all members before the first access specifier in a class are considered private, while in a struct they are public.

Is there a guarantee e.g. that the public variables will be first in memory then the private variable?

There is no such guarantee. When there is no inheritance, the memory will be allocated to class members in the order in which you declare them within the same access group. It is up to the compiler to decide if the public member variables should be placed ahead of the private / protected ones or vice versa. Like C, C++ can add padding in between class members.

Inheritance makes things more complicated, because data members of the base class need to be placed within the derived class as well. On top of that, there is virtual inheritance and multiple inheritance, with complex rules.

I basically want to achieve the same [layout], but I also want get/set methods and also maybe other methods.

If you make all data members of your class private, and add accessor member functions (that's what C++ calls "methods" from other languages) you would achieve this effect.