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hi @all,

I'm designing a new simple protocol and now I need a header for it.
There should only be 3 fields, one 32bit and 2 16bit fields -> 64bit
header (8byte). Due to the used library I need the data as a (unsigned
char*) for delivering. I thought about a struct to store the header but
I don't know how to cast it to the expected format for delivering.
Is there a way to store all this information and deliver it in a char[8]
which would be exactly 8byte long?

thanks,
Andreas

Andreas Müller wrote:
> hi @all,
>
> I'm designing a new simple protocol and now I need a header for it.
> There should only be 3 fields, one 32bit and 2 16bit fields -> 64bit
> header (8byte). Due to the used library I need the data as a
(unsigned
> char*) for delivering. I thought about a struct to store the header
but
> I don't know how to cast it to the expected format for delivering.
> Is there a way to store all this information and deliver it in a
char[8]
> which would be exactly 8byte long?

#pragma pack(...) // see your compiler documentation for alignment

struct protocol {
int one;
short two;
short three;
};

protocol p;
// ...
char buf[8] = "";
memcpy (buf, (void*) &p, sizeof (buf));

Instead of int and short you better use the appropriate typedefs for
your platform.

::A::