Hi,

I am trying to figure out where the standard, specifically the object model, defines alignment and its requirements on addresses.

In [basic.align]#1 it says:

Object types have alignment requirements ([basic.fundamental], [basic.compound]) which place restrictions on the addresses at which an object of that type may be allocated. An alignment is an implementation-defined integer value representing the number of bytes between successive addresses at which a given object can be allocated.

I am surprised by the second sentence, that the alignment of a type is the difference between two addresses at which objects of this type can be placed. It says nothing on the value of the addresses themselves. For that matter, values of type double could be allocated at the addresses 0x1, 0x9, 0x11, 0x19, etc.

Digging deeper, I started wondering if the definition of alignment is vague out of necessity, because it seems the standard also does not define whether an address is an integer. It is described in various places that an address (represented by a pointer) can be value-preservingly converted to an integer and back, but that does not describe the nature of an address.

In any way, I would be glad if someone could point me to the right place that establishes that alignment, which is defined as an integer, requires a divisibility of an address by that number.

Thanks a lot!

Bernhard