Re: is it ok to use c++ STL containers like string inside a structure and pass in message ques?

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 5 Feb 2009 00:46:32 -0800 (PST)
Message-ID:
<f22e71ff-f30f-4621-8e3f-f782be685a5f@a39g2000prl.googlegroups.com>
On Feb 4, 2:14 pm, SG <s.gesem...@gmail.com> wrote:

On 4 Feb., 10:59, ashjas <ash...@gmail.com> wrote:

I tried to use string containers inside a structure and pass
it in message queue to recieve at other end...but got
different kinds of errors..segmentation fault..junk values
etc...


Sounds like you just copy a struct byte by byte. This won't
work for all kinds of objects. For those it'll work we say
they are "trivially copyable".


Formally, there are no "trivially copyable" objects in C++, at
least not in this sense. "Trivially copyable" (e.g.
memcpy'able) only works within the program; not between
programs.

In practice, you can often count on bytes being 8 bits on both
ends, so arrays of unsigned char, or even char, are "trivially
copiable". Everything else needs to be serialized in some form
or another.

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