C ++ #pragma pack

Question

以下陈述实际上做了什么以及它的影响是什么？

#pragma pack(push,8)

Answer 1

It pushes the current pack setting onto a stack (so that you can restore it later via pop ) and then sets the alignment for struct elements to 8 bytes. Anything which is not naturally aligned to an 8 byte boundary will have padding bytes inserted before it to maintain the required alignment.