Understanding alignment in g++

[Ian Lance Taylor]

Yang Zhang <yanghatespam@gmail.com> writes:

> Is there something analogous to __alignof__ that can tell me the
> required alignment?  (E.g., if I'm serializing data and trying to pack
> together everything without padding...)

As far as I know there is no way to ask for the alignment required by
the target machine.  However, if you use __attribute__ ((packed)), then
gcc will use the available instructions to retrieve the field: a
misaligned full word read if possible and appropriate, otherwise byte
reads.

Ian