[pardoned_turkey]

It's even worse: for example, the first one isn't undefined, it's merely unspecified - i.e., "depends on the system in a well-known and predictable way," not "you're doing something very wrong and the result is chaos."

[aw1621107]

> it's merely unspecified - i.e., "depends on the system in a well-known and predictable way,"

I think that should be implementation-defined behavior, not unspecified behavior? IIRC unspecified behavior in C is not required to be known or consistent.

[plorkyeran]

My bigger problem with the first one is that the explanation is incorrect and it isn't actually about structure padding. The explanation is making the incorrect assumption that `sizeof(int)` is always 4, but it isn't. `sizeof(*(&s))` can be as small as 2.