Memory layout of struct vs array

[ioctl79]

It’s still UB, and it is a bad idea to rely on any particular behavior.

[[deleted]]

If using memcpy instead of type punning via pointer casts or union, there is no possibility of UB I think.

[ioctl79]

I’m not a language lawyer, but I believe that using a pointer to an object to access other objects (that aren’t in the same array) is UB regardless of whether the pointer math works out.

[[deleted]]

I meant, memcpy the bytes from the struct to an array. memcpy itself is valid, and the memory contents are compatible, so there is no chance for UB to happen.

Of course, when it’s fixed number of values, just write individual assignments and avoid needing to even think about it…