VS2013 Error: LNK2019 When trying to build ZeroMQ server

Question

I'm trying to build this simple ZeroMQ server in C++ on Visual Studio 2013.

#include "stdafx.h"
#include "zmq.hpp"
#include <string>
#include <iostream>
#include <windows.h>

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    // Prepare context and socket
    zmq::context_t ctx(1);
    zmq::socket_t sckt(ctx, ZMQ_REP);
    sckt.bind("tcp://*:5555");

    while (true) {
        zmq::message_t request;

        // Wait for next request from client
        sckt.recv(&request);
        std::cout << "Received Hello" << endl;
        Sleep(1);

        // Send reply back to client
        zmq::message_t reply(5);
        memcpy((void*)reply.data(), "World", 5);
        sckt.send(reply);
    }
    return EXIT_SUCCESS;
}

However, I'm getting error LNK2019 when I try to build the VS project. Below is the compiler output:

1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_errno referenced in function "public: __thiscall zmq::error_t::error_t(void)" (??0error_t@zmq@@QAE@XZ)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_strerror referenced in function "public: virtual char const * __thiscall zmq::error_t::what(void)const " (?what@error_t@zmq@@UBEPBDXZ)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_ctx_new referenced in function "public: __thiscall zmq::context_t::context_t(int,int)" (??0context_t@zmq@@QAE@HH@Z)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_ctx_set referenced in function "public: __thiscall zmq::context_t::context_t(int,int)" (??0context_t@zmq@@QAE@HH@Z)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_ctx_destroy referenced in function "public: void __thiscall zmq::context_t::close(void)" (?close@context_t@zmq@@QAEXXZ)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_msg_init referenced in function "public: __thiscall zmq::message_t::message_t(void)" (??0message_t@zmq@@QAE@XZ)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_msg_init_size referenced in function "public: __thiscall zmq::message_t::message_t(unsigned int)" (??0message_t@zmq@@QAE@I@Z)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_msg_send referenced in function "public: bool __thiscall zmq::socket_t::send(class zmq::message_t &,int)" (?send@socket_t@zmq@@QAE_NAAVmessage_t@2@H@Z)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_msg_recv referenced in function "public: bool __thiscall zmq::socket_t::recv(class zmq::message_t *,int)" (?recv@socket_t@zmq@@QAE_NPAVmessage_t@2@H@Z)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_msg_close referenced in function "public: __thiscall zmq::message_t::~message_t(void)" (??1message_t@zmq@@QAE@XZ)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_msg_data referenced in function "public: void * __thiscall zmq::message_t::data(void)" (?data@message_t@zmq@@QAEPAXXZ)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_socket referenced in function "public: __thiscall zmq::socket_t::socket_t(class zmq::context_t &,int)" (??0socket_t@zmq@@QAE@AAVcontext_t@1@H@Z)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_close referenced in function "public: void __thiscall zmq::socket_t::close(void)" (?close@socket_t@zmq@@QAEXXZ)
1>ZeroMQServer.obj : error LNK2019: unresolved external symbol __imp__zmq_bind referenced in function "public: void __thiscall zmq::socket_t::bind(char const *)" (?bind@socket_t@zmq@@QAEXPBD@Z)
1>D:\[ Source Code ]\C++\ZeroMQServer\Debug\ZeroMQServer.exe : fatal error LNK1120: 14 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

I have installed the ZeroMQ binary v4.0.4 and updated the VS project properties to point to ZeroMQ's include and lib paths. Specifically, this is what I have updated in the project properties (I suspect some of these settings may be redundant):

1. Configuration Properties > VC++ Directories > Include Directories: Added '$(ZEROMQ_HOME)\include'
2. Configuration Properties > VC++ Directories > Library Directories: Added '$(ZEROMQ_HOME)\lib'
3. Configuration Properties > C/C++ > General > Additional Include Directories: Added '$(ZEROMQ_HOME)\include'
4. Configuration Properties > Linker > Input > Additional Dependencies: Added 'libzmq-v120-mt-4_0_4.lib;libzmq-v120-mt-gd-4_0_4.lib'

I'm on Win 7, 64-bit Edition. Please help me resolve this.

Answer 1

According to the library names on zeromq.org, you are trying to link the same library twice: first with the release version, and then with the debug versions.

Remove libzmq-v120-mt-gd-4_0_4.lib from your Release configuration, and remove libzmq-v120-mt-4_0_4.lib from your Debug configuration.

[edit]

Your application probably is 32bit, and the library you are trying to link with is 64bit. (You can use dumpbin to determine what architecture a .lib file is for, see this answer for an example. Please use the 32bit library, or change your application to 64bit.