When structures are defined, the compiler is allowed to add paddings (spaces without actual data) so that members fall in address boundaries that are easier to access for the CPU. For example, on a 32-bit CPU, 32-bit members should start at addresses that are multiple of 4 bytes in order to be efficiently accessed (read … Read more
Considering the mentioned platforms, yes, packed structs are completely fine to use. x86 and x86_64 always supported unaligned access, and contrary to the common belief, unaligned access on these platforms has (almost) the same speed as aligned access for a long time (there’s no such thing that unaligned access is much slower). The only drawback … Read more
Before answering, I would like to give you some data from Wiki Data structure alignment is the way data is arranged and accessed in computer memory. It consists of two separate but related issues: data alignment and data structure padding. When a modern computer reads from or writes to a memory address, it will do … Read more