Yes, they can be. Why not? Bit-fields in unions behave in the same way they behave anywhere else. There's nothing special about bit-fields in unions (or unions with bit-fields).
I have used bit field with a structure like this,
struct
{
unsigned int is_static: 1;
unsigned int is_extern: 1;
unsigned int is_auto: 1;
} flags;
Now i wondered to see if this can be done with a union so i modified …
I've seen this pattern used a lot in C & C++.
unsigned int flags = -1; // all bits are true
Is this a good portable way to accomplish this? Or is using 0xffffffff or ~0 better?
Any portable code that uses bitfields seems to distinguish between little- and big-endian platforms. See the declaration of struct iphdr in linux kernel for an example of such code. I fail to understand why bit endianness is an issue at …