[zeromq-dev] help: memcpy with message_t

[Richard_Newton at waters.com]

Well, if your subscriber relies on it being null terminated you should use c_str(), data() may work but its implementation dependant, not guaranteed
to null terminate.

If you don't need a null terminated you can use size() instead of size() + 1. E.g.

// To message
memcpy(message.data(), zipcode.data(), zipcode.size());

// From message
std::string result(static_cast<const char*>(message.data()), message.size());

Ric.




From:	liuchuanbo at gmail.com
To:	"ZeroMQ development list" <zeromq-dev at lists.zeromq.org>
Date:	06/08/2013 03:41 PM
Subject:	Re: [zeromq-dev] help: memcpy with message_t
Sent by:	zeromq-dev-bounces at lists.zeromq.org



Hi, Admir

Thanks.
You're right.

zipcode.data() is also correct.

--
Best Regards,
Roy Liu

On 2013-8-6, at 下午9:58, Admir Efendic <admir.efendic at gmail.com> wrote:

      been ages but shouldn't this work:

      memcpy ((void *) message.data(), zipcode.c_str(), zipcode.size()+1);



      2013/8/6 <liuchuanbo at gmail.com>
        I'm using PUB-SUB test with zmq.
        pls give me some advices. Thanks.


        My code:
        ---------------------
        std::string zipcode = "10001";
        zmq::message_t message(zipcode.size()+1);

        // it's OK.
        memcpy ((void *) message.data(), "10001", zipcode.size()+1);

        // it's Error, subscriber always receives bizarre code.
        memcpy ((void *) message.data(), &zipcode, zipcode.size()+1);
        ---------------------



        --
        Best Regards,
        Roy Liu


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