Compile simple hello world ZeroMQ C example, compile flags?

Question

Trying to compile the example hello_world.c from the zeromq tutorial: http://zguide.zeromq.org/page:all#Ask-and-Ye-Shall-Receive Pretty sure I have everything installed in OSX Mountain Lion.

clang -Wall hwserver.c -o hwserver

gives me an error:

Undefined symbols for architecture x86_64:  
"_zmq_bind", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_ctx_new", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_msg_close", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_msg_data", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_msg_init", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_msg_init_size", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_msg_recv", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_msg_send", referenced from:  
  _main in hwserver-OgrEe6.o  
"_zmq_socket", referenced from:  
  _main in hwserver-OgrEe6.o  
ld: symbol(s) not found for architecture x86_64  
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I'm not the most experienced in C. Not sure if I sure be adding a compiler flag for the zmq dylib or headers or my $PATH being off.

in /usr/local/lib:

libzmq.3.dylib
libzmq.a
libzmq.dylib
libzmq.la

and in /usr/local/include:

zmq.h
zmq_utils.h

and echo $PATH:

/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/local/lib/:/usr/local/include/

Answer 1

You list the ZeroMQ libraries in your question, but you do not actually link with them. Change the command line to this:

clang -Wall hwserver.c -o hwserver -L/usr/local/lib -lzmq

Explanation of the extra arguments:

• -L/usr/local/lib tells the linker to add a path (/usr/local/lib) to the library search path.
• -lzmq tells the library to link with the zmq library.

The $PATH environment variable have nothing to do with this, it just tells the shell where to look for commands.