Data alignment in C++, standard and portability

Question

I want to construct an object of class T by using ::operator new(size_t) and placement new.

To \"extend\" the size of ch

Answer 1

1) Yes. From the section on pointer comparisons, the standard states that pointers to later members must compare as greater than pointers to earlier members. Edit: As pointed out by Martin, the standard only mandates this for POD structs.

2) Yes. Data alignment is not affected by the size of the allocation.

The thing is, nothing in the standard actually guarantees that the trick of using arrays this way works (IIRC).

struct something {
    ...
    char buf[1];
};

However, this is done so commonly that it is a de-facto standard. The standards folks, last time I checked, were working on a way that they could codify these existing practices (It's already made its way into the C standard and it's only a matter of time before it's standardized in C++).