Re: Serializing binary data for use accross different platforms

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 5 May 2010 12:15:38 -0700 (PDT)

Message-ID:

<e311c699-c55c-466e-9041-41f16d97ba2b@s29g2000yqd.googlegroups.com>

On May 5, 7:51 pm, Victor Bazarov <v.baza...@comcast.invalid> wrote:

On 5/5/2010 2:40 PM, Peter Olcott wrote:

If only integer base types are used, then it seems that
serializing data for cross platform use requires only two
things:
(1) Decomposing aggregate types into sequences of integral
types.
(2) Accounting for Endianess (Big, Little, Mixed).

Endianess can be determined at run time by casting known
values (such as 0x12345678, and 0x1234) for unsigned int and
unsigned short into char*.

Is there anything that I am missing here?

Uh... Only the possible problems with different
representations of negative values (one's complement vs two's
complement vs signed magnitude).

And the fact that the number of bits in a char can vary, and
that the size isn't always 2,4,8... And that there can be bits
which don't contribute to the representation, but must have some
particular value. And that even for a 4 byte 2's complement,
there are quite a few different orderings possible: I've seen at
least three on popular machines.

--
James Kanze