Adam Badura wrote:
At first english is not my primary language and all my books on C++ are in polish so I have to translate. I'm afraid I'm not using correct words or terms but I will try to be as descripting as possible to be understood.
I have a question on placement of subobjects in a class (or struct - what I know of standard this will be the same). In S. Lippman's "Inside the C++ Object Model" I found that standard only guaranties that subobjects are placed in specific sequence (not to get inside details) but there is no guarante that compiler doesn't place some additional objects (for his internal use) at the begining of object in between subobjects or at the end. (I looked also in Stroustrup's "The C++ Programming Language" and "The Design and Evolution of C++" but have found nothing - but I wasn't looking that hard).
So, if I have a class:
class point2d { public: double x; double y; };
and make an object of it
point2d pp = new point2d;
point2d * pp = new point2d;
than ther is no guaranty that
reinterpret_cast<double*>(pp) will give me addres of point2d::x.
Correct. But many compilers allow you to specify a packing which can ensure that your expression will work as specified. That is compiler specific but nor part of the C++ standard.