alt Hacker Newslooks like I was wrong, but here is the de-facto standard I was relying on over the years ;-). Not that I've memcpied many structs to file directly btw. http://www.catb.org/esr/structure-packing/
looks like I was wrong, but here is the de-facto standard I was relying on over the years ;-). Not that I've memcpied many structs to file directly btw. http://www.catb.org/esr/structure-packing/
The general struct layout algorithm is that you lay out the first member at the address of the struct (this is guaranteed by C), and then subsequent fields in order (also guaranteed by C). What isn't guaranteed is how fields get their alignment, in particular shenanigans you can do with allocating fields in the padding of their prior field, and bitfields in general are horribly underspecified.
In practice, C doesn't do any padding shenanigans, but C++ does (but only for non-POD structs, and then you discover there's several slightly different definitions that mean basically "POD", so have fun predicting which one is the one that actually matters for your use case).