[zeromq-dev] Example for building against ZMQ with CMake + UDP Multicast Support

[Stephan Opfer]

On 10.01.2017 22:20, Luca Boccassi wrote:
> luca at luca-desktop:/tmp$ apt-cache policy libzmq3-dev
> libzmq3-dev:
>    Installed: 1483950852.598befc
>    Candidate: 1483950852.598befc
>    Version table:
>   *** 1483950852.598befc 0
>          500http://download.opensuse.org/repositories/home:/zeromq:/git-draft/Debian_8.0/
> ./ Packages
>          100 /var/lib/dpkg/status
>       4.2.1-2 0
>          103http://httpredir.debian.org/debian/  sid/main amd64 Packages
>       4.2.0-2 0
>          104http://httpredir.debian.org/debian/  stretch/main amd64 Packages
>       4.0.5+dfsg-2+deb8u1 0
>          500http://httpredir.debian.org/debian/  jessie/main amd64 Packages
>          500http://security.debian.org/  jessie/updates/main amd64 Packages
> luca at luca-desktop:/tmp$ g++ `pkg-config --libs --cflags libzmq`
> Discovery.cpp -o test
> luca at luca-desktop:/tmp$ ./test
>
>
> Builds just fine (binary runs and never exits not sure if that's
> intended). I am honestly not sure why your linker is being picky. This
> is on Debian 8 with gcc 4.9.2
$ apt-cache policy libzmq3-dev
libzmq3-dev:
   Installed: 1483950852.598befc
   Candidate: 1483950852.598befc
   Version table:
  *** 1483950852.598befc 500
         500 
http://download.opensuse.org/repositories/home:/zeromq:/git-draft/xUbuntu_16.04 
./ Packages
         100 /var/lib/dpkg/status
      4.1.4-7 500
         500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages

A little bit strang, that I don't see a Version named 4.2.x like you 
have. Nevertheless, this would only create a lack of the new UDP 
Multicast feature, but my linker complains about standard functions like 
zmq_ctx_new...

I am using g++ version 5.4.0 on Ubuntu 16.04 LTS. I further guaranteed 
that there is only one libzmq.
Its location is: /usr/lib/x86_64-linux-gnu/libzmq.so.5.1.2
And I checked that the wanted symbol is in there with: readelf -Ws 
/usr/lib/x86_64-linux-gnu/libzmq.so.5.1.2

Normally under this circumstances problems like mismatching architecture 
of the .so is the case, but I can't see any hints for that.

-- 
Distributed Systems Research Group
Stephan Opfer  T. +49 561 804-6283  F. +49 561 804-6277
Univ. Kassel,  FB 16,  Wilhelmshöher Allee 73,  D-34121 Kassel
WWW: http://www.uni-kassel.de/go/vs_stephan-opfer/