Packing/unpacking binary data in C - doubles, 64 bits

[Bruce Labitt]

Kevin D. Clark wrote:
> 1:  If I were you, I would start using datatypes like uint64_t and
> int32_t in your protocol code.
>
>   
I'll try to do that. 
> 2:  Typically, binary stuff is sent over the network in "network byte
> order" and network byte order is big-endian.  This statement is not
> universally agreed to -- in fact I used to work at a shop where they'd
> never even considered this problem and it turned out that they were
> sending (most) stuff over the wire in little-endian format.
>
>   
That only works if both ends are the same - definitely not portable.  In 
my case, the client is little-endian and the server is big-endian.
> 3:  Here's some sample code that unpacks a 64-bit integer in network
> byte order:
>
>  unsigned char raw[8];  /* these are the raw bytes 
>                            you got from the wire */
>  uint64_t u64result;
>
>  u64result = (((uint64_t)raw[0]) << 56) |
>              (((uint64_t)raw[1]) << 48) |
>              (((uint64_t)raw[2]) << 40) |
>              (((uint64_t)raw[3]) << 32) |
>              (((uint64_t)raw[4]) << 24) |
>              (((uint64_t)raw[5]) << 16) |
>              (((uint64_t)raw[6]) << 8) |
>              (((uint64_t)raw[7]));
>
>   
Thanks for the sample code!  How about packing?  What do you do about sign?
> 4:  Sending binary doubles over the wire can be very complicated.
>
>   
Why?  Encode to a standard.  IEEE-754 would be logical.  Is that 
complicated?  What am I missing?  In my OP, the url I provided has 
functions that pack and unpack IEEE754 floats and doubles.  I never 
looked at the floats, but the double stuff works.
> 5:  If at all possible, consider encoding your protocol in ASCII text
> rather than sending binary stuff on the wire.
>   
Again, why?   Sure it is easier to debug.  When I am just trying stuff 
out, I use text.  For performance, I always end up using binary. 
> Kind regards,
>
> --kevin
>   
I always learn something from these discussions. 

Thanks Again,
Bruce