structure alignment in C++09

[hendrixj]

Does C++ 09 give ways to pack structures or specify data item alignment?
Many compilers offer a way to pack structs, but they aren't part of the language. I was thinking Danny or someone said that C++09 might fill in this gap.

[Danny]

Yes it does. A new feature called attributes which looks like this:
[[attribute]] will allow you to control the alignment of aggregates and classes.
Originally, the C++0x draft had two new keywords: alignof and alignas (which were described in detail in a former C++ 10 minute solution: http://www.devx.com/cplus/10MinuteSolution/38542/1954 ). However, as it happens often when a new standard is being drafted, those keywords were replaced with the more general notion of attributes, which can be used for other purposes.
I will dedicate an article to this issue soon.

[Peter_APIIT]

Good job.

[Danny]

This is how attributes are used in C++09:
http://www.devx.com/cplus/Article/41694/0/page/1

[hendrixj]

Thanks for the article.

Will there be a "packed" attribute, similar to gcc's __attribute__((packed))?

Does the [[align]] attribute allow you to "pack" an item? That is, could I use align(1) to force a double right after a char?

[Danny]

Whether "packing" is allowed is implementation-dependent of course but at least the syntax is:
struct S[[align(char)]]{
/**/
};